50054 Zip Code Natural Disasters and Weather Extremes
Hot Rankings
The chance of earthquake damage in 50054 Zip Code is about the same as Iowa average and is much lower than the national average. The risk of tornado damage in 50054 Zip Code is higher than Iowa average and is much higher than the national average.
Earthquake Index, #481
| 50054 Zip Code | 0.00 |
| Iowa | 0.00 |
| U.S. | 1.81 |
The earthquake index value is calculated based on historical earthquake events data using USA.com algorithms. It is an indicator of the earthquake level in a region. A higher earthquake index value means a higher chance of an earthquake.
Volcano Index, #1
| 50054 Zip Code | 0.0000 |
| Iowa | 0.0000 |
| U.S. | 0.0023 |
The volcano index value is calculated based on the currently known volcanoes using USA.com algorithms. It is an indicator of the possibility of a region being affected by a possible volcano eruption. A higher volcano index value means a higher chance of being affected.
Tornado Index, #150
| 50054 Zip Code | 285.92 |
| Iowa | 236.74 |
| U.S. | 136.45 |
The tornado index value is calculated based on historical tornado events data using USA.com algorithms. It is an indicator of the tornado level in a region. A higher tornado index value means a higher chance of tornado events.
Other Weather Extremes Events
A total of 5,223 other weather extremes events within 50 miles of 50054 Zip Code were recorded from 1950 to 2010. The following is a break down of these events:
| Type | Count | Type | Count | Type | Count | Type | Count | Type | Count |
| Avalanche: | 0 | Blizzard: | 28 | Cold: | 30 | Dense Fog: | 13 | Drought: | 16 |
| Dust Storm: | 0 | Flood: | 732 | Hail: | 1,760 | Heat: | 6 | Heavy Snow: | 70 |
| High Surf: | 0 | Hurricane: | 0 | Ice Storm: | 39 | Landslide: | 0 | Strong Wind: | 73 |
| Thunderstorm Winds: | 1,997 | Tropical Storm: | 0 | Wildfire: | 0 | Winter Storm: | 79 | Winter Weather: | 54 |
| Other: | 326 | ||||||||
Volcanos Nearby
No volcano is found in or near 50054 Zip Code.
Historical Earthquake Events
No historical earthquake events that had recorded magnitudes of 3.5 or above found in or near 50054 Zip Code.
No historical earthquake events found in or near 50054 Zip Code.
Historical Tornado Events
A total of 105 historical tornado events that had recorded magnitude of 2 or above found in or near 50054 Zip Code.
| Distance (miles) | Date | Magnitude | Start Lat/Log | End Lat/Log | Length | Width | Fatalities | Injuries | Property Damage | Crop Damage | Affected County |
| 6.3 | 1986-09-28 | 4 | 41°46'N / 93°20'W | 41°46'N / 93°00'W | 14.00 Miles | 250 Yards | 0 | 0 | 2.5M | 0 | Jasper |
| 7.4 | 1999-04-08 | 2 | 41°31'N / 93°20'W | 41°40'N / 93°15'W | 11.00 Miles | 175 Yards | 0 | 1 | 1.0M | 0 | Jasper |
| Brief Description: broken track As mentioned in the narrative above, an intense low pressure formed to the southwest of Iowa. The low tracked northeast and lifted into eastern Nebraska. Ahead of the low, a strong low level jet of around 60 knots continued through the day. A nearly stationary frontal boundary extended east from the low. It lifted into southeast Nebraska during the day, but made little progress into southern Iowa. Lines of thunderstorms formed along the boundary through the day and lifted north rapidly. These storms were elevated in nature and as a result produced most of their severe weather in the form of hail. As the day unfolded, a sharp dry line was clearly evident on the satellite as early as 1600 UTC across Kansas. This line raced east during the day. By afternoon, a speed max had rotated around the upper low to the southwest with wind speeds measured by the Lathrop wind profiler at 100 knots at 500 mb by mid afternoon. Jet stream winds were in excess of 120 knots at the same time. Combined with the dynamic situation mentioned above, considerable moisture convergence took place near the triple point between the warm front and the dry line. Surface dew points pooled into to the mid 60s to even a few 70 degree F. dew point readings over northwest Missouri, southeast Nebraska, and southwest Iowa. Meanwhile, dew points fell into the upper 20s over northeast Kansas and south central Nebraska behind the dry line, with teens over central and south central Kansas. Thunderstorms erupted along the dry line by mid day and advanced east through the afternoon. Low level helicity values topped out between 500 and 600 (m/s)**2 just before the first tornadoes formed. Most of the storms in the warm sector became tornadic quickly. The northern limit of the tornado tracks extended about 10 miles or so north of the warm front. Tracks became intermittent very quickly as soon as the storms crossed the surface warm front due to the layer of very cold air just north of the front. Surface temperatures on the cold side of the front were only in the upper 40s to mid 50s. The entire day was very active. Initially, warm air advection thunderstorms produced hail at many locations of central and northern Iowa. Most of is was just below severe levels however. The activity that developed during the afternoon was a combination of warm air advection and the approach of the dryline. At the beginning of the event, the main weather feature was in the form of hail. There were numerous reports of hail three quarters to one and three quarters inch in diameter. The largest hail fell in Guthrie and Dallas Counties with reports of golf ball size hail. One of the storms in the initial wave of afternoon activity became stronger as it moved into southern Story County. Initially, high winds of 60 MPH or more swept through Sheldahl area of Boone County. Greene County was also affected by high winds from the storms. A tornado dropped out of the storm as it moved into the Slater area and was on the ground for about 2 miles. Initial estimates showed 44 homes and businesses damaged in Story County, one was destroyed with major damage to another. Thirty six homes and four businesses were damaged in the town of Slater. Two people were injured during the passage of the tornado. One of the injuries involved a 70 year old man who was picked up by the tornadoes winds and thrown about 10 feet before he latched on to something. His shoulder was dislocated and he required 6 stitches due to his injuries in his hand. High winds northeast of Slater knocked several cars of a Burlington Northern freight train off the tracks after they were blown more than one quarter mile down the track. It was not possible to determine of the cars were knocked off by the tornado or high winds however. This band of storms continue to race and develop northeast through the afternoon. Damage became more sporadic, however high winds occurred as far northeast as Hardin County, with 70 MPH winds reported near New Providence. Hail reports came in from as far northeast as Grundy and Black Hawk Counties, though it was only three quarters of an inch in diameter. Attention then shifted to the tornadic storms that formed near the dry line. During the afternoon, six more tornadoes touched down in Iowa, several of which were long track tornadoes. The first touched down in Taylor County and tracked through Adams, Cass, and Adair Counties. This tornado had was an F4 intensity tornado in parts of Adair and Adams Counties. Damage was extensive with $1,000,000 damage reported in both Adams and Adair Counties. Entire farmsteads were swept clean by the tornado. At one time this tornado was a mile wide wedge with a damage path nearly two miles wide due to the circulation around the tornado. Eyewitness reports indicated that the tornado split into two distinct tornadoes at times, similar to what occurred with the intense F4 tornado in Adair County of 27 May 1995. One of the farmsteads hit near Nodaway was levelled. Reports indicated that a check was blown from the house nearly 100 miles and was found in the town of Jefferson in Greene County. Other checks and papers were found strewn along the path, stretching from Jefferson all the way back to northwest Taylor County. In Adair County, one account indicated pieces of sheet metal from one farm was lifted and deposited six miles away from the farm. Two people were injured by this tornado, one in Adams County with the other in Adair County. One of the injuries Adair County was serious as a man suffered a broken back when the tornado lifted his semi-tractortrailer truck from the Interstate and threw it into a nearby field. The other injuries from this tornado were minor enough that the people were taken to the hospital, treated, and released. There was one account of a horse being picked up by the tornado. It was lifted into the air and thrown through a stand of pine trees 40 feet high. The horse suffered serious injuries and required significant medical attention do to lacerations. The horse amazingly did survive against all odds, though was said would likely lose sight in one eye. The next tornado touched down in Union County and tracked across Madison and Dallas Counties. This tornado had an F4 strength in Union and decreased to a strong F2 in Madison Counties before intensifying again to near F3 strength as it headed into Dallas County. Damage in Union County was around $2,000,000, and around $350,000 in Madison County. There was one person injured by this tornado in Union County. In an amazing account, the Union County Sheriff reported watching as the tornado lifted the car in front of him 35 feet in the air and throwing it 250 feet. The driver was inside during this time and came out of the situation uninjured. Five coal cars were knocked off the tracks in Union County by the tornado as well. This tornado also had a double structure. From eye witness accounts, which also can be shown on Doppler radar imagery, suggest a small rope like tornado passed through the Twelve Mile Lake area shortly before the passage of the main tornado. The next tornado was a weak tornado which touched down about 4 miles west of downtown Des Moines. The tornado did little damage, but did affect one house and several trees. The tornado was seen by a local television sky camera. A short time later, an F2 tornado touched down in Warren County and tracked into southeast Polk County. The track was over rural areas and damage from it was relatively minor. A more significant F3 tornado tracked from northern Lucas County, and weakened to an F2 as it moved across Warren, part of marion, and into Jasper County. One house was destroyed in Lucas County with the four people inside sustaining minor injuries. Once again, this tornado tracked across mostly rural areas, though it did hit a business and two homes in Jasper County and did $1,000,000 in damage. One person was injured in Jasper County. The last tornado touched down in Davis County at Bloomfield and tracked northeast into Wapello County with a maximum strength of F3. Damage in Davis County was over $500,000 as 64 homes and businesses were damaged in the Bloomfield area. To the northeast, the area of the tornado track was mostly rural and damage was limited to outbuildings for the most part. One farmstead reported severe damage near Floris in Davis County. The house was nearly levelled and several outbuildings were completely destroyed. Parts of the house and outbuildings were found as far as 5 miles away from the farmstead. As the storms moved north, high winds were produced over Story County east of Story City. High winds toppled a tractor semi-trailer truck east of Story City on Interstate 35, injuring the driver. Two cars and a truck were also blown off Interstate 35 in Hamilton County. Four people were injured. Two were taken to the hospital, treated, and released. Two were listed in serious condition, one with a neck fracture, the other with a shoulder fracture. The later incident appeared to be from the rear flank downdraft behind the storm and not the initial gust front. From the preliminary data, 178 homes and business were damaged or destroyed by the tornadic storms as well as countless outbuildings. There were several reports of livestock loss as well. It is truly amazing that there was no loss of life during this event and even more amazing is the fact that the injuries that did occur were all minor. Twenty counties in Iowa experienced serious damage from the storms of the day. Iowa Governor Vilsack declared several counties in Iowa disaster areas. These included Taylor, Union, Adams, and Adair Counties. High winds accompanied the storms as the moved through Appanoose County. A local gas station recorded an 81 MPH wind gust as the storms cut a half mile wide swath of destruction west of Moravia. There were numerous reports of cattle killed by the storms. Some were killed by the tornadoes and flying debris, others by lightning. Reports in Adair County, northwest of Fontanelle indicated about 25 head of cattle were struck by lightning shortly before a tornado moved through that area. As the area of storms that produced the high winds north of Ames in central Iowa moved north, they lost their punch. A few of the storms did remain quite strong however. As the area of thunderstorms moved through Cerro Gordo County, high winds blew down a 60 foot corn crib and did some other damage on a farm near Rockwell. | |||||||||||
| 10.4 | 1973-06-04 | 2 | 41°42'N / 93°03'W | 41°44'N / 93°01'W | 1.30 Miles | 250 Yards | 0 | 0 | 250K | 0 | Jasper |
| 10.5 | 1953-06-07 | 2 | 41°25'N / 93°55'W | 41°42'N / 92°45'W | 63.30 Miles | 200 Yards | 0 | 0 | 0K | 0 | Madison |
| 10.5 | 1965-08-26 | 2 | 41°52'N / 93°15'W | 41°49'N / 93°12'W | 3.00 Miles | 100 Yards | 0 | 0 | 25K | 0 | Jasper |
| 11.9 | 1968-04-03 | 2 | 41°34'N / 93°05'W | 41°37'N / 93°00'W | 5.20 Miles | 150 Yards | 0 | 0 | 25K | 0 | Jasper |
| 12.3 | 1966-06-11 | 2 | 41°34'N / 93°33'W | 41°40'N / 93°21'W | 12.20 Miles | 150 Yards | 0 | 0 | 25K | 0 | Polk |
| 13.4 | 1986-09-28 | 4 | 41°45'N / 93°36'W | 41°46'N / 93°21'W | 6.00 Miles | 250 Yards | 0 | 0 | 2.5M | 0 | Polk |
| 13.4 | 1976-07-28 | 2 | 41°31'N / 93°21'W | 1.20 Miles | 100 Yards | 0 | 0 | 25K | 0 | Polk | |
| 13.6 | 1965-08-26 | 2 | 41°54'N / 93°18'W | 41°52'N / 93°15'W | 1.90 Miles | 100 Yards | 0 | 2 | 25K | 0 | Story |
| 14.9 | 1962-05-07 | 2 | 41°54'N / 93°18'W | 0 | 0 | 250K | 0 | Story | |||
| 16.6 | 1981-04-10 | 2 | 41°53'N / 93°10'W | 41°57'N / 93°05'W | 5.60 Miles | 500 Yards | 0 | 9 | 2.5M | 0 | Marshall |
| 17.2 | 1983-05-06 | 2 | 41°35'N / 93°32'W | 1.00 Mile | 60 Yards | 0 | 0 | 2.5M | 0 | Polk | |
| 17.3 | 1978-09-16 | 3 | 41°58'N / 93°11'W | 41°52'N / 93°00'W | 11.30 Miles | 200 Yards | 0 | 0 | 0K | 0 | Marshall |
| 17.9 | 1979-03-29 | 2 | 41°26'N / 93°30'W | 41°31'N / 93°21'W | 9.30 Miles | 60 Yards | 0 | 0 | 250K | 0 | Warren |
| 18.3 | 1974-06-18 | 4 | 41°44'N / 93°37'W | 41°31'N / 93°32'W | 15.30 Miles | 400 Yards | 2 | 50 | 25.0M | 0 | Polk |
| 18.8 | 1990-03-13 | 2 | 41°56'N / 93°30'W | 41°53'N / 93°24'W | 3.00 Miles | 60 Yards | 0 | 0 | 2.5M | 0 | Story |
| 19.1 | 1978-09-16 | 3 | 41°52'N / 93°00'W | 41°42'N / 92°46'W | 16.40 Miles | 200 Yards | 2 | 2 | 250K | 0 | Jasper |
| 19.5 | 1990-03-13 | 2 | 41°44'N / 93°37'W | 41°56'N / 93°30'W | 12.00 Miles | 60 Yards | 0 | 15 | 2.5M | 0 | Polk |
| 20.0 | 1959-05-10 | 2 | 41°36'N / 93°36'W | 0.30 Mile | 50 Yards | 0 | 0 | 3K | 0 | Polk | |
| 23.8 | 1986-06-29 | 2 | 41°35'N / 93°44'W | 41°36'N / 93°37'W | 5.00 Miles | 50 Yards | 0 | 0 | 2.5M | 0 | Polk |
| 24.1 | 1998-06-29 | 2 | 41°46'N / 93°48'W | 41°36'N / 93°36'W | 18.30 Miles | 150 Yards | 0 | 83 | 10.0M | 75K | Polk |
| Brief Description: A complex weather situation was set up over the central U.S. as a mesoscale convective system passed to the south of Iowa during the overnight hours and early morning of the 29th. Initially, the surface warm front was located to the south of this system. That was not actually the case aloft however. During the predawn hours the surface front surged north and by sunrise was located across northeast Nebraska across northern Iowa. The airmass was very unstable to the south of the front with dew point temperatures will in the 70s F. The initial development of thunderstorms took place during the early part of the day over northeast Nebraska. The storms became severe quickly as they moved and developed eastward into Iowa. By mid morning, the storms had formed a nearly east to west line. Storm relative inflow into the line was around 40 knots. The storms produced a variety of severe weather across Iowa. They initially moved east across the northern and central counties, but then began sinking sinking southeast. The dominant severe weather with the storms was extremely high winds. Damage was very widespread across the state. Winds in excess of 100 MPH were reported with one unofficial wind speed measured at 126 MPH in the town of Washington at 1405 CST. In one unusual story, high winds hit Mahaska County. Three miles south of New Sharon, a puppy was tied to its dog house which was picked up by the wind. The dog house and puppy were lifted over the top of a two car garage and a corn crib. Both were deposited in the farm yard. When found the dog house was upside down and the puppy, though scared, was fine. There were several tornadoes during the event. One of the longer track well defined tornadoes was the initial tornado. It was on the ground for about 11 miles as it swept across Crawford County. Several residences, outbuildings, grain bins, and trees were damaged along its path. Reports indicate that between 30 and 50 residences were damaged by this tornado. There were several small tornadoes in central Iowa. They had short tracks and only touched down briefly. One cut a mile long path east of Marshalltown through a corn field and a grove of trees. Another in Dallas County was on the ground through mostly open country for two miles. High winds were a major problem with these storms. Many places reported winds over 80 MPH with incredible tree damage and numerous buildings damaged or destroyed. At least 38 counties were declared disaster areas by the Federal Government due to the severe damage and flooding. A final total will not be available before publication deadlines, however preliminary data have been included. In the Des Moines County Warning Area these included: Wright, Franklin, Butler, Bremer, Hamilton, Hardin, Grundy, Crawford, Carroll, Greene, Boone, Story, Marshall, Audubon, Guthrie, Dallas, Polk, Jasper, Cass, Adair, Madison, Warren, Marion, Adams, and Taylor. One of the hardest hit Counties was Polk County. Damage appeared to be from straight line winds based on a storm survey that was done following the event. The damage occurred over the southwest semicircle of a large meso low in contact with the ground. Due to the rapid translational speed of 50 to 75 MPH, winds were enhanced on the southwest semicircle of the meso low. Smaller scale winds could have been embedded within this circulation as well. There was little evidence of small scale convergent tornadic damage, however aerial surveys did make some suggestion and eye witness accounts of sightings were quite numerous in the metro Des Moines area. All trees and debris were laid down to the south or southeast. The major damage swath as 3 to 7 miles wide northwest of Camp Dodge, with a widening into a full blown derecho after that. The event was born a few miles northwest of Perry, between Rippey and Berkley in southwest Boone County. The mile wide damage path expanded to over 3 miles by the time it reached full intensity near highway 169 between Woodward and Perry. The path continued through Granger, Camp Dodge, and Johnston. The path was nearly 7 miles wide near Granger. A second, smaller, meso low passed near Madrid, downing power lines. This meso low matured near Jester Park Golf Course, causing significant structural damage to houses. The two meso lows merged near the NWS Forecast Office in Johnston, with two miles of power poles snapped off between Johnston and Granger. Much of the damage along the most severe track was in the F1 intensity category, with speeds in the 75 to 110 MPH range. A few spots along the path, such as in the Granger and Camp Dodge area, sustained sufficient damage to justify F2 winds, 110 to 155 MPH. It appears a tornado or family of tornadoes touched down southeast of Berkley and moved southeast into the Pleasant Hill area just east of Des Moines. The track was intermittent, indicating either one tornado touching down occasionally, or one or more weak tornadoes rotating around the meso circulation. The worst effected metro areas were the Granger area, Johnston, and the northeast side of Des Moines proper. A duplex in Granger was flattened by the winds. There were several reports of roofs being ripped off of stores and houses in the metropolitan Des Moines area. Several small private planes were flipped at a small air field north of Des Moines. There were also several reports of semi-tractortrailer trucks being blown over on Interstate 35. Heavy construction equipment was overturned on Interstate 35/80 just north of Des Moines. Damage was extensive to the east side of Des Moines proper. To make matters worse, following the passage of the main line of thunderstorms, a second line of severe thunderstorms developed and moved across the same areas already hit. The storms were smaller, but did produce brief tornado touch downs and hail up to 2.5 inches in diameter. The second line of storms did eventually combine with the first and moved southeast across the rest of the state. Damage was widespread across the state and it will be months before final numbers are in. Estimates from Polk County alone are near $100 million in damage including cleanup. Totals were still being tallied at this writing, however a few include over $11 million in damage from initial claims in Johnston and $726,000 from West Des Moines just to city buildings and systems. West Des Moines was on the far west edge of the major damage however. In addition to the property damage, at least 125 people were injured during the storm. Most of the injuries were caused by flying debris and many were not serious. Fortunately there were no fatalities. Heavy damage was reported by MidAmerica Energy. On a state wide report, they indicated 200,000 homes were without electricity, effecting over 500,000 people, at one time during the storm. In the metropolitan Des Moines area, 100,000 homes were without electricity at the height of the storm. That number was reduced to around 25,000 36 hours later. The worst damaged areas were without power for 5 to 6 days. Heavy damage was also reported by local telephone and cable systems. In Polk County, the worst damage extended from the Camp Dodge area into the northeast parts of Des Moines. At least 462 homes in the metro Des Moines area sustained significant damage. Statewide, 80 homes were destroyed, 559 sustained severe damage, with 1416 others receiving moderate damage. In the Camp Dodge area, 80 to 90 percent of the brick buildings were damaged with the roofs removed from many of them. Lightning from the storms struck the WSR-88D in the midst of the storm. The radar was taken out of service for more than 24 hours because of this. In addition to the severe weather, flooding quickly became a problem. Iowa soil was nearly saturated as the weather pattern had been very wet for six weeks previous. Although rainfall was not extreme, one to three inches of rain fell over a several county area. This caused widespread urban flooding across north central into central Iowa, though damage from the flooding was not serious. Crop damage was very difficult to determine and will not likely be clear until the fall harvest. Reports from some of the local extension agents say damage to the corn ranged up to 75% destroyed in areas with the highest wind, such as the swath that went through central Iowa in association with the tornado there. No doubt losses will be in the hundreds of thousands of dollars if not in the millions. Accounts of damage were of course too numerous to document here as the areal extent of the storms was very large. Countless reports of parts of crop fields being flattened were received. Semi-tractortrailer trucks were overturned by the high winds both in the Des Moines metro area as well as in Newton. Trees were found on houses over a large part of the state. One news reported wrote "there is not a power pole standing between Fort Dodge and Oskaloosa". Though not figuratively true, this statement does point out the extensive damage that occurred with these storms.l | |||||||||||
| 24.2 | 1966-10-14 | 2 | 41°36'N / 93°48'W | 41°44'N / 93°36'W | 13.50 Miles | 50 Yards | 0 | 0 | 2.5M | 0 | Polk |
| 24.7 | 2007-09-30 | 2 | 41°28'N / 92°52'W | 41°30'N / 92°49'W | 3.00 Miles | 1250 Yards | 0 | 0 | 500K | 250K | Mahaska |
| Brief Description: EVENT NARRATIVE: Tornado moved into Mahaska County from Marion County, then continued northeast into Jasper County. EPISODE NARRATIVE: A very dynamic weather system moved into Iowa during the afternoon of the 30th. The system was more reminiscent of what one would expect in April or May. A close upper level low pressure, negatively tilted, lifted northeast through the central U.S. The structure was very classic in appearance with a well defined comma cloudy, dry slot, and warm conveyor in place. By the early evening, the surface low became stacked with the upper low and was located over eastern Nebraska. A defined dry line extended south-southeast out of the low. Surface temperatures warmed into the mid 70s to mid 80s ahead of the low, with dew points in the mid to upper 60s. Dew points behind the dry line dropped into the upper 30s to mid 40s. The airmass became unstable by the late afternoon with CAPE values around 1000 J/kg and lifted indices in the -2 to -4 C. range. Strong dynamics were in place with a 90 kt mid level jet in place, a low level jet of 60 to 70 kts, and an effective shear of 45 to 55 kts. The freezing level was quite high ahead of the approaching low and was between 13,000 and 14,000 feet. The high freezing level, combined with the limited CAPE of 100 to 200 J/kg in the -10 to -30 C. layer of the atmosphere, limited hail production. The downdraft CAPE was in the 600 to 1000 J/kg range, with an LCL of about 1250 meters. Thunderstorms formed in two locations. The first was along the east edge of the dry slot across Kansas. These storms became severe and lifted northeast quite rapidly into southern and central Iowa. Spotty wind damage was reported and one of the storms dropped one inch diameter hail in Marion County. The storms became tornadic as the moved into central Iowa. During the evening of Sunday 30 September 2007 two tornadoes struck portions of Marion, Jasper, Mahaska, and Poweshiek Counties. The first tornado produced EF0 to EF2 damage along its track and was rated EF2 on the Enhanced Fujita Scale with maximum winds of 125 mph. The track was 22 miles in length from 4 miles northeast of Pella to 1 mile north of Interstate 80, 2 miles west of Malcom. Much of the track was three to five tenths of a mile wide, but as wide as seven tenths of a mile at times. The second, shorter and weaker tornado was 5 miles in length and rated EF1 on the Enhanced Fujita Scale. The track began just south of Highway 6, 2.75 miles northwest of Malcom with a maximum width of 150 yards narrowing to 25-50 yards. The storm hit a farmstead just east of 110th street producing EF1 damage with speeds just under 100 mph. The tornadoes caused extensive damage on a farmstead near Malcom with three barns totally destroyed. The barns were 20 by 30 feet, 20 by 40 feet, and 60 by 100 feet. In addition, numerous other damage reports came in from along the track. Fortunately, there were no deaths or injuries from the tornadoes. Thunderstorms also formed close to the upper low center on the nose of the dry punch. There were several reports funnel clouds, along with spotty reports of high winds and hail. A storm chaser confirmed a tornado touchdown 2 NNW of Lytton in Sac county and was on the ground until 4 W of Jolley in Calhoun county. The tornado was in open country and was a small EF0 tornado. One inch diameter hail fell in Sac County, with numerous reports of pea to marble size hail. | |||||||||||
| 25.1 | 1969-06-11 | 2 | 41°50'N / 92°47'W | 1.00 Mile | 100 Yards | 0 | 0 | 25K | 0 | Marshall | |
| 25.3 | 1950-06-15 | 3 | 41°59'N / 93°36'W | 41°58'N / 93°29'W | 5.60 Miles | 300 Yards | 0 | 5 | 0K | 0 | Story |
| 25.4 | 1966-10-14 | 3 | 41°32'N / 93°06'W | 41°07'N / 93°14'W | 29.50 Miles | 200 Yards | 0 | 0 | 25K | 0 | Jasper |
| 25.4 | 1967-06-08 | 2 | 42°00'N / 93°36'W | 42°02'N / 93°19'W | 14.40 Miles | 100 Yards | 0 | 0 | 250K | 0 | Story |
| 25.5 | 2007-09-30 | 2 | 41°30'N / 92°49'W | 41°34'N / 92°45'W | 6.00 Miles | 1250 Yards | 0 | 0 | 1.0M | 500K | Jasper |
| Brief Description: EVENT NARRATIVE: Tornado moved into Jasper County from Mahaska County, then continued northeast into Poweshiek County. EPISODE NARRATIVE: A very dynamic weather system moved into Iowa during the afternoon of the 30th. The system was more reminiscent of what one would expect in April or May. A close upper level low pressure, negatively tilted, lifted northeast through the central U.S. The structure was very classic in appearance with a well defined comma cloudy, dry slot, and warm conveyor in place. By the early evening, the surface low became stacked with the upper low and was located over eastern Nebraska. A defined dry line extended south-southeast out of the low. Surface temperatures warmed into the mid 70s to mid 80s ahead of the low, with dew points in the mid to upper 60s. Dew points behind the dry line dropped into the upper 30s to mid 40s. The airmass became unstable by the late afternoon with CAPE values around 1000 J/kg and lifted indices in the -2 to -4 C. range. Strong dynamics were in place with a 90 kt mid level jet in place, a low level jet of 60 to 70 kts, and an effective shear of 45 to 55 kts. The freezing level was quite high ahead of the approaching low and was between 13,000 and 14,000 feet. The high freezing level, combined with the limited CAPE of 100 to 200 J/kg in the -10 to -30 C. layer of the atmosphere, limited hail production. The downdraft CAPE was in the 600 to 1000 J/kg range, with an LCL of about 1250 meters. Thunderstorms formed in two locations. The first was along the east edge of the dry slot across Kansas. These storms became severe and lifted northeast quite rapidly into southern and central Iowa. Spotty wind damage was reported and one of the storms dropped one inch diameter hail in Marion County. The storms became tornadic as the moved into central Iowa. During the evening of Sunday 30 September 2007 two tornadoes struck portions of Marion, Jasper, Mahaska, and Poweshiek Counties. The first tornado produced EF0 to EF2 damage along its track and was rated EF2 on the Enhanced Fujita Scale with maximum winds of 125 mph. The track was 22 miles in length from 4 miles northeast of Pella to 1 mile north of Interstate 80, 2 miles west of Malcom. Much of the track was three to five tenths of a mile wide, but as wide as seven tenths of a mile at times. The second, shorter and weaker tornado was 5 miles in length and rated EF1 on the Enhanced Fujita Scale. The track began just south of Highway 6, 2.75 miles northwest of Malcom with a maximum width of 150 yards narrowing to 25-50 yards. The storm hit a farmstead just east of 110th street producing EF1 damage with speeds just under 100 mph. The tornadoes caused extensive damage on a farmstead near Malcom with three barns totally destroyed. The barns were 20 by 30 feet, 20 by 40 feet, and 60 by 100 feet. In addition, numerous other damage reports came in from along the track. Fortunately, there were no deaths or injuries from the tornadoes. Thunderstorms also formed close to the upper low center on the nose of the dry punch. There were several reports funnel clouds, along with spotty reports of high winds and hail. A storm chaser confirmed a tornado touchdown 2 NNW of Lytton in Sac county and was on the ground until 4 W of Jolley in Calhoun county. The tornado was in open country and was a small EF0 tornado. One inch diameter hail fell in Sac County, with numerous reports of pea to marble size hail. | |||||||||||
| 25.7 | 1978-09-16 | 3 | 41°42'N / 92°46'W | 41°39'N / 92°42'W | 4.10 Miles | 200 Yards | 4 | 43 | 2.5M | 0 | Poweshiek |
| 26.1 | 1962-05-28 | 2 | 41°52'N / 92°47'W | 0 | 5 | 250K | 0 | Marshall | |||
| 26.1 | 1969-06-06 | 2 | 41°52'N / 92°47'W | 0 | 0 | 25K | 0 | Marshall | |||
| 26.3 | 1975-06-18 | 2 | 41°22'N / 93°30'W | 0 | 0 | 3K | 0 | Warren | |||
| 26.5 | 1964-06-22 | 2 | 41°24'N / 92°54'W | 41°28'N / 92°48'W | 6.40 Miles | 200 Yards | 0 | 0 | 25K | 0 | Marion |
| 26.7 | 1999-04-08 | 2 | 41°09'N / 93°31'W | 41°31'N / 93°21'W | 22.50 Miles | 150 Yards | 0 | 0 | 70K | 0 | Warren |
| Brief Description: intermittent track As mentioned in the narrative above, an intense low pressure formed to the southwest of Iowa. The low tracked northeast and lifted into eastern Nebraska. Ahead of the low, a strong low level jet of around 60 knots continued through the day. A nearly stationary frontal boundary extended east from the low. It lifted into southeast Nebraska during the day, but made little progress into southern Iowa. Lines of thunderstorms formed along the boundary through the day and lifted north rapidly. These storms were elevated in nature and as a result produced most of their severe weather in the form of hail. As the day unfolded, a sharp dry line was clearly evident on the satellite as early as 1600 UTC across Kansas. This line raced east during the day. By afternoon, a speed max had rotated around the upper low to the southwest with wind speeds measured by the Lathrop wind profiler at 100 knots at 500 mb by mid afternoon. Jet stream winds were in excess of 120 knots at the same time. Combined with the dynamic situation mentioned above, considerable moisture convergence took place near the triple point between the warm front and the dry line. Surface dew points pooled into to the mid 60s to even a few 70 degree F. dew point readings over northwest Missouri, southeast Nebraska, and southwest Iowa. Meanwhile, dew points fell into the upper 20s over northeast Kansas and south central Nebraska behind the dry line, with teens over central and south central Kansas. Thunderstorms erupted along the dry line by mid day and advanced east through the afternoon. Low level helicity values topped out between 500 and 600 (m/s)**2 just before the first tornadoes formed. Most of the storms in the warm sector became tornadic quickly. The northern limit of the tornado tracks extended about 10 miles or so north of the warm front. Tracks became intermittent very quickly as soon as the storms crossed the surface warm front due to the layer of very cold air just north of the front. Surface temperatures on the cold side of the front were only in the upper 40s to mid 50s. The entire day was very active. Initially, warm air advection thunderstorms produced hail at many locations of central and northern Iowa. Most of is was just below severe levels however. The activity that developed during the afternoon was a combination of warm air advection and the approach of the dryline. At the beginning of the event, the main weather feature was in the form of hail. There were numerous reports of hail three quarters to one and three quarters inch in diameter. The largest hail fell in Guthrie and Dallas Counties with reports of golf ball size hail. One of the storms in the initial wave of afternoon activity became stronger as it moved into southern Story County. Initially, high winds of 60 MPH or more swept through Sheldahl area of Boone County. Greene County was also affected by high winds from the storms. A tornado dropped out of the storm as it moved into the Slater area and was on the ground for about 2 miles. Initial estimates showed 44 homes and businesses damaged in Story County, one was destroyed with major damage to another. Thirty six homes and four businesses were damaged in the town of Slater. Two people were injured during the passage of the tornado. One of the injuries involved a 70 year old man who was picked up by the tornadoes winds and thrown about 10 feet before he latched on to something. His shoulder was dislocated and he required 6 stitches due to his injuries in his hand. High winds northeast of Slater knocked several cars of a Burlington Northern freight train off the tracks after they were blown more than one quarter mile down the track. It was not possible to determine of the cars were knocked off by the tornado or high winds however. This band of storms continue to race and develop northeast through the afternoon. Damage became more sporadic, however high winds occurred as far northeast as Hardin County, with 70 MPH winds reported near New Providence. Hail reports came in from as far northeast as Grundy and Black Hawk Counties, though it was only three quarters of an inch in diameter. Attention then shifted to the tornadic storms that formed near the dry line. During the afternoon, six more tornadoes touched down in Iowa, several of which were long track tornadoes. The first touched down in Taylor County and tracked through Adams, Cass, and Adair Counties. This tornado had was an F4 intensity tornado in parts of Adair and Adams Counties. Damage was extensive with $1,000,000 damage reported in both Adams and Adair Counties. Entire farmsteads were swept clean by the tornado. At one time this tornado was a mile wide wedge with a damage path nearly two miles wide due to the circulation around the tornado. Eyewitness reports indicated that the tornado split into two distinct tornadoes at times, similar to what occurred with the intense F4 tornado in Adair County of 27 May 1995. One of the farmsteads hit near Nodaway was levelled. Reports indicated that a check was blown from the house nearly 100 miles and was found in the town of Jefferson in Greene County. Other checks and papers were found strewn along the path, stretching from Jefferson all the way back to northwest Taylor County. In Adair County, one account indicated pieces of sheet metal from one farm was lifted and deposited six miles away from the farm. Two people were injured by this tornado, one in Adams County with the other in Adair County. One of the injuries Adair County was serious as a man suffered a broken back when the tornado lifted his semi-tractortrailer truck from the Interstate and threw it into a nearby field. The other injuries from this tornado were minor enough that the people were taken to the hospital, treated, and released. There was one account of a horse being picked up by the tornado. It was lifted into the air and thrown through a stand of pine trees 40 feet high. The horse suffered serious injuries and required significant medical attention do to lacerations. The horse amazingly did survive against all odds, though was said would likely lose sight in one eye. The next tornado touched down in Union County and tracked across Madison and Dallas Counties. This tornado had an F4 strength in Union and decreased to a strong F2 in Madison Counties before intensifying again to near F3 strength as it headed into Dallas County. Damage in Union County was around $2,000,000, and around $350,000 in Madison County. There was one person injured by this tornado in Union County. In an amazing account, the Union County Sheriff reported watching as the tornado lifted the car in front of him 35 feet in the air and throwing it 250 feet. The driver was inside during this time and came out of the situation uninjured. Five coal cars were knocked off the tracks in Union County by the tornado as well. This tornado also had a double structure. From eye witness accounts, which also can be shown on Doppler radar imagery, suggest a small rope like tornado passed through the Twelve Mile Lake area shortly before the passage of the main tornado. The next tornado was a weak tornado which touched down about 4 miles west of downtown Des Moines. The tornado did little damage, but did affect one house and several trees. The tornado was seen by a local television sky camera. A short time later, an F2 tornado touched down in Warren County and tracked into southeast Polk County. The track was over rural areas and damage from it was relatively minor. A more significant F3 tornado tracked from northern Lucas County, and weakened to an F2 as it moved across Warren, part of marion, and into Jasper County. One house was destroyed in Lucas County with the four people inside sustaining minor injuries. Once again, this tornado tracked across mostly rural areas, though it did hit a business and two homes in Jasper County and did $1,000,000 in damage. One person was injured in Jasper County. The last tornado touched down in Davis County at Bloomfield and tracked northeast into Wapello County with a maximum strength of F3. Damage in Davis County was over $500,000 as 64 homes and businesses were damaged in the Bloomfield area. To the northeast, the area of the tornado track was mostly rural and damage was limited to outbuildings for the most part. One farmstead reported severe damage near Floris in Davis County. The house was nearly levelled and several outbuildings were completely destroyed. Parts of the house and outbuildings were found as far as 5 miles away from the farmstead. As the storms moved north, high winds were produced over Story County east of Story City. High winds toppled a tractor semi-trailer truck east of Story City on Interstate 35, injuring the driver. Two cars and a truck were also blown off Interstate 35 in Hamilton County. Four people were injured. Two were taken to the hospital, treated, and released. Two were listed in serious condition, one with a neck fracture, the other with a shoulder fracture. The later incident appeared to be from the rear flank downdraft behind the storm and not the initial gust front. From the preliminary data, 178 homes and business were damaged or destroyed by the tornadic storms as well as countless outbuildings. There were several reports of livestock loss as well. It is truly amazing that there was no loss of life during this event and even more amazing is the fact that the injuries that did occur were all minor. Twenty counties in Iowa experienced serious damage from the storms of the day. Iowa Governor Vilsack declared several counties in Iowa disaster areas. These included Taylor, Union, Adams, and Adair Counties. High winds accompanied the storms as the moved through Appanoose County. A local gas station recorded an 81 MPH wind gust as the storms cut a half mile wide swath of destruction west of Moravia. There were numerous reports of cattle killed by the storms. Some were killed by the tornadoes and flying debris, others by lightning. Reports in Adair County, northwest of Fontanelle indicated about 25 head of cattle were struck by lightning shortly before a tornado moved through that area. As the area of storms that produced the high winds north of Ames in central Iowa moved north, they lost their punch. A few of the storms did remain quite strong however. As the area of thunderstorms moved through Cerro Gordo County, high winds blew down a 60 foot corn crib and did some other damage on a farm near Rockwell. | |||||||||||
| 27.2 | 1990-03-13 | 3 | 42°01'N / 93°23'W | 42°08'N / 93°18'W | 9.00 Miles | 100 Yards | 0 | 1 | 250K | 0 | Story |
| 27.3 | 1960-06-16 | 2 | 41°23'N / 93°34'W | 2.00 Miles | 150 Yards | 0 | 0 | 25K | 0 | Warren | |
| 28.5 | 1956-08-12 | 3 | 41°32'N / 92°45'W | 41°35'N / 92°40'W | 5.10 Miles | 200 Yards | 0 | 8 | 25K | 0 | Poweshiek |
| 28.7 | 2007-06-22 | 2 | 41°29'N / 93°46'W | 41°28'N / 93°39'W | 6.00 Miles | 150 Yards | 0 | 0 | 700K | 15K | Warren |
| Brief Description: EVENT NARRATIVE: Tornado spotted by amateur radio, law enforcement, Warren County Emergency Manager, and trained spotters. Touched down near Cumming and lifted south of the Norwalk area. Damage was done to several buildings. One house had the roof taken off. Numerous trees and power lines were downed. The tornado track was generally east-southeast, however the track was not straight. EPISODE NARRATIVE: A rather complex weather situation unfolded during the day on the 22nd. The situation was complicated by the convection that occurred during the previous night. An outflow boundary from the previous nights convection pushed south across the CWA, reaching the southern part by sunrise. This boundary combined with a quasi-stationary frontal boundary that was across the southern counties. The atmosphere became unstable quite rapidly during the late morning and early afternoon. Surface low pressure was located over southwest Iowa, with a warm front extending east South of the warm front temperatures warmed to around 90 F. with dew points in the upper 60s to low 70s. Surface based CAPE rose to 3000 to 4000 J/kg with the lifted index falling into the -8 to -10 C. range. The cap broke by around 1800 UTC as an MCS began to develop over central Iowa. The environment was fairly favorable with 30 to 40 kts of effective shear and precipitable water values around 1.5 inches. Available cape in the -10 to -30 C. layer of the atmosphere was in the 300 to 500 J/kg range. DCAPE values were between 600 and 800 J/kg. Two tornadoes touched down in Warren County. First indication of ground contact from the first tornado was adjacent to I-35 0.60 miles north of the Cumming, IA/G-14 interchange and approximately 1 mile NW of the town of Cumming. Ground contact evident to the southeast along a path of approximately 125 degrees. First structural damage (EF1) noted at a farm house at G14 and 20th Ave. Path width at this point estimated at 100 yards. Continuous ground contact southeast to farmstead at G14 and 25th Ave where north facing garage was destroyed (EF1) and outbuildings and trailer damaged. The tornado continued SE and reached widest point of approximately 200 yards striking outbuildings. Debris swath is noted to NE and also SE indicating the possibility of multi vortex circulation. A farmstead at 30th Ave and Clark street sustained EF1 damage to grain bin and outbuildings. Path width approximately 150 yards. Corn from grain bin was noted well downstream at end of track, some corn impacted side of Phillips home in SE Norwalk. Continuous ground contact ended and path narrowed considerably just north of Clarke St. near the Happy Apple Orchard. This resulted in a continuous tornado path of 2.2 miles. Intermittent damage path continued SE for 1.5 miles across fields and wooded areas with path of 30 to 50 yards. Next structural damage occurred to a light garage (EF0). The track turned E/NE Approximately 080 degrees for .6 mile, with intermittent damage consisting of snapped and mangled trees. Path width 30 to 50 yards. Mature 2' diameter trees along farm pond snapped at trunk and tops of trees deposited to the NE. The track turns SE for .75 mile before again turning E/NE. Narrow swath of tree damage noted. The track continues ENE (approximately 070 degrees) across Highway 28 where EF0 damage was noted. Ground scouring/swirl marks noted along 1.9 mile track ending at the Phillips home on the SE corner of Norwalk where EF2 damage was observed. Tornado appeared to quickly dissipate on the NE of the home. Maximum path width 200 yards along the over 7 mile long track. The second tornado was first verified over the Legacy Golf Course, just NW of the Norwalk Fire Station. It is interesting to note the tornado passed directly over the fire station, producing a circular pattern in the gravel on the roof, and blowing out two overhead doors. The tornado was narrow, with most damage consisting of tree damage up to EF1 and light structural damage as it moved to the SE. The path width ranges from 10 yards to a maximum of approximately 100-150 yards. This NW to SE tornado path crossed less than .25 miles of the path of the West to East moving Cumming to Norwalk Tornado. A farmstead on R57 south of Coolidge St. sustained tree damage from tornado #2. This is just south of the Phillips home that was damaged by the first tornado. Winds were estimated at 125 MPH in the first tornado, and 100 MPH in the second. Fortunately, there were no injuries during the tornado occurrences themselves, however one person was injured during recovery. LCL levels were lower than the previous day, in the 750 to 1000 meter range. As the complex evolved, the primary modes of severe weather were hail and high wind. The freezing level was lower than the previous day, at 13,900 feet and many of the storms contained at least some hail. The hail was not overly large, with most reports in the three quarter to one inch range. During the storms evolution, there were several bow echo segments, resulting in high winds. Winds of 80 MPH occurred southwest of Norwalk, in the rear flank downdraft of the supercell over the county in association with the tornadoes. Some of the other high winds included a wind gust of near 85 MPH in Madison County where a house had about one third of the shingles removed and a northeast facing overhang removed, 78 MPH in Tama, and 75 MPH at the Des Moines Airport, and 65 MPH in Carroll. A downburst occurred in Marion County south-southwest of Pleasantville, with winds estimated to 60 MPH. The storms were prolific rainfall producers. Rainfall of 2 to 4 inches was common in central, into north central and parts of northeast Iowa. Spotty reports of up to 6 inches in a 2 to 3 hour period were received. There were numerous reports of water flowing over highways as well as bridge and highway washouts. | |||||||||||
| 29.0 | 2007-09-30 | 2 | 41°34'N / 92°45'W | 41°42'N / 92°36'W | 12.00 Miles | 1250 Yards | 0 | 0 | 2.5M | 1.0M | Poweshiek |
| Brief Description: EVENT NARRATIVE: Tornado moved into Poweshiek County from Jasper County. It lifted west of Malcom. EPISODE NARRATIVE: A very dynamic weather system moved into Iowa during the afternoon of the 30th. The system was more reminiscent of what one would expect in April or May. A close upper level low pressure, negatively tilted, lifted northeast through the central U.S. The structure was very classic in appearance with a well defined comma cloudy, dry slot, and warm conveyor in place. By the early evening, the surface low became stacked with the upper low and was located over eastern Nebraska. A defined dry line extended south-southeast out of the low. Surface temperatures warmed into the mid 70s to mid 80s ahead of the low, with dew points in the mid to upper 60s. Dew points behind the dry line dropped into the upper 30s to mid 40s. The airmass became unstable by the late afternoon with CAPE values around 1000 J/kg and lifted indices in the -2 to -4 C. range. Strong dynamics were in place with a 90 kt mid level jet in place, a low level jet of 60 to 70 kts, and an effective shear of 45 to 55 kts. The freezing level was quite high ahead of the approaching low and was between 13,000 and 14,000 feet. The high freezing level, combined with the limited CAPE of 100 to 200 J/kg in the -10 to -30 C. layer of the atmosphere, limited hail production. The downdraft CAPE was in the 600 to 1000 J/kg range, with an LCL of about 1250 meters. Thunderstorms formed in two locations. The first was along the east edge of the dry slot across Kansas. These storms became severe and lifted northeast quite rapidly into southern and central Iowa. Spotty wind damage was reported and one of the storms dropped one inch diameter hail in Marion County. The storms became tornadic as the moved into central Iowa. During the evening of Sunday 30 September 2007 two tornadoes struck portions of Marion, Jasper, Mahaska, and Poweshiek Counties. The first tornado produced EF0 to EF2 damage along its track and was rated EF2 on the Enhanced Fujita Scale with maximum winds of 125 mph. The track was 22 miles in length from 4 miles northeast of Pella to 1 mile north of Interstate 80, 2 miles west of Malcom. Much of the track was three to five tenths of a mile wide, but as wide as seven tenths of a mile at times. The second, shorter and weaker tornado was 5 miles in length and rated EF1 on the Enhanced Fujita Scale. The track began just south of Highway 6, 2.75 miles northwest of Malcom with a maximum width of 150 yards narrowing to 25-50 yards. The storm hit a farmstead just east of 110th street producing EF1 damage with speeds just under 100 mph. The tornadoes caused extensive damage on a farmstead near Malcom with three barns totally destroyed. The barns were 20 by 30 feet, 20 by 40 feet, and 60 by 100 feet. In addition, numerous other damage reports came in from along the track. Fortunately, there were no deaths or injuries from the tornadoes. Thunderstorms also formed close to the upper low center on the nose of the dry punch. There were several reports funnel clouds, along with spotty reports of high winds and hail. A storm chaser confirmed a tornado touchdown 2 NNW of Lytton in Sac county and was on the ground until 4 W of Jolley in Calhoun county. The tornado was in open country and was a small EF0 tornado. One inch diameter hail fell in Sac County, with numerous reports of pea to marble size hail. | |||||||||||
| 29.4 | 1966-04-19 | 3 | 41°51'N / 92°43'W | 41°52'N / 92°42'W | 0 | 0 | 250K | 0 | Poweshiek | ||
| 29.4 | 1974-06-18 | 2 | 41°57'N / 93°41'W | 2.00 Miles | 200 Yards | 0 | 0 | 250K | 0 | Story | |
| 29.5 | 1991-03-22 | 3 | 41°54'N / 93°38'W | 42°14'N / 93°22'W | 27.00 Miles | 70 Yards | 0 | 0 | 2.5M | 0 | Story |
| 30.7 | 1951-06-01 | 3 | 42°04'N / 92°55'W | 1.50 Miles | 880 Yards | 0 | 7 | 0K | 0 | Marshall | |
| 30.9 | 1959-05-31 | 2 | 42°03'N / 93°26'W | 42°13'N / 93°11'W | 17.00 Miles | 440 Yards | 0 | 0 | 250K | 0 | Story |
| 31.8 | 1999-04-08 | 2 | 41°11'N / 93°45'W | 41°30'N / 93°31'W | 25.00 Miles | 100 Yards | 0 | 0 | 75K | 0 | Warren |
| Brief Description: very intermittent track in rural areas As mentioned in the narrative above, an intense low pressure formed to the southwest of Iowa. The low tracked northeast and lifted into eastern Nebraska. Ahead of the low, a strong low level jet of around 60 knots continued through the day. A nearly stationary frontal boundary extended east from the low. It lifted into southeast Nebraska during the day, but made little progress into southern Iowa. Lines of thunderstorms formed along the boundary through the day and lifted north rapidly. These storms were elevated in nature and as a result produced most of their severe weather in the form of hail. As the day unfolded, a sharp dry line was clearly evident on the satellite as early as 1600 UTC across Kansas. This line raced east during the day. By afternoon, a speed max had rotated around the upper low to the southwest with wind speeds measured by the Lathrop wind profiler at 100 knots at 500 mb by mid afternoon. Jet stream winds were in excess of 120 knots at the same time. Combined with the dynamic situation mentioned above, considerable moisture convergence took place near the triple point between the warm front and the dry line. Surface dew points pooled into to the mid 60s to even a few 70 degree F. dew point readings over northwest Missouri, southeast Nebraska, and southwest Iowa. Meanwhile, dew points fell into the upper 20s over northeast Kansas and south central Nebraska behind the dry line, with teens over central and south central Kansas. Thunderstorms erupted along the dry line by mid day and advanced east through the afternoon. Low level helicity values topped out between 500 and 600 (m/s)**2 just before the first tornadoes formed. Most of the storms in the warm sector became tornadic quickly. The northern limit of the tornado tracks extended about 10 miles or so north of the warm front. Tracks became intermittent very quickly as soon as the storms crossed the surface warm front due to the layer of very cold air just north of the front. Surface temperatures on the cold side of the front were only in the upper 40s to mid 50s. The entire day was very active. Initially, warm air advection thunderstorms produced hail at many locations of central and northern Iowa. Most of is was just below severe levels however. The activity that developed during the afternoon was a combination of warm air advection and the approach of the dryline. At the beginning of the event, the main weather feature was in the form of hail. There were numerous reports of hail three quarters to one and three quarters inch in diameter. The largest hail fell in Guthrie and Dallas Counties with reports of golf ball size hail. One of the storms in the initial wave of afternoon activity became stronger as it moved into southern Story County. Initially, high winds of 60 MPH or more swept through Sheldahl area of Boone County. Greene County was also affected by high winds from the storms. A tornado dropped out of the storm as it moved into the Slater area and was on the ground for about 2 miles. Initial estimates showed 44 homes and businesses damaged in Story County, one was destroyed with major damage to another. Thirty six homes and four businesses were damaged in the town of Slater. Two people were injured during the passage of the tornado. One of the injuries involved a 70 year old man who was picked up by the tornadoes winds and thrown about 10 feet before he latched on to something. His shoulder was dislocated and he required 6 stitches due to his injuries in his hand. High winds northeast of Slater knocked several cars of a Burlington Northern freight train off the tracks after they were blown more than one quarter mile down the track. It was not possible to determine of the cars were knocked off by the tornado or high winds however. This band of storms continue to race and develop northeast through the afternoon. Damage became more sporadic, however high winds occurred as far northeast as Hardin County, with 70 MPH winds reported near New Providence. Hail reports came in from as far northeast as Grundy and Black Hawk Counties, though it was only three quarters of an inch in diameter. Attention then shifted to the tornadic storms that formed near the dry line. During the afternoon, six more tornadoes touched down in Iowa, several of which were long track tornadoes. The first touched down in Taylor County and tracked through Adams, Cass, and Adair Counties. This tornado had was an F4 intensity tornado in parts of Adair and Adams Counties. Damage was extensive with $1,000,000 damage reported in both Adams and Adair Counties. Entire farmsteads were swept clean by the tornado. At one time this tornado was a mile wide wedge with a damage path nearly two miles wide due to the circulation around the tornado. Eyewitness reports indicated that the tornado split into two distinct tornadoes at times, similar to what occurred with the intense F4 tornado in Adair County of 27 May 1995. One of the farmsteads hit near Nodaway was levelled. Reports indicated that a check was blown from the house nearly 100 miles and was found in the town of Jefferson in Greene County. Other checks and papers were found strewn along the path, stretching from Jefferson all the way back to northwest Taylor County. In Adair County, one account indicated pieces of sheet metal from one farm was lifted and deposited six miles away from the farm. Two people were injured by this tornado, one in Adams County with the other in Adair County. One of the injuries Adair County was serious as a man suffered a broken back when the tornado lifted his semi-tractortrailer truck from the Interstate and threw it into a nearby field. The other injuries from this tornado were minor enough that the people were taken to the hospital, treated, and released. There was one account of a horse being picked up by the tornado. It was lifted into the air and thrown through a stand of pine trees 40 feet high. The horse suffered serious injuries and required significant medical attention do to lacerations. The horse amazingly did survive against all odds, though was said would likely lose sight in one eye. The next tornado touched down in Union County and tracked across Madison and Dallas Counties. This tornado had an F4 strength in Union and decreased to a strong F2 in Madison Counties before intensifying again to near F3 strength as it headed into Dallas County. Damage in Union County was around $2,000,000, and around $350,000 in Madison County. There was one person injured by this tornado in Union County. In an amazing account, the Union County Sheriff reported watching as the tornado lifted the car in front of him 35 feet in the air and throwing it 250 feet. The driver was inside during this time and came out of the situation uninjured. Five coal cars were knocked off the tracks in Union County by the tornado as well. This tornado also had a double structure. From eye witness accounts, which also can be shown on Doppler radar imagery, suggest a small rope like tornado passed through the Twelve Mile Lake area shortly before the passage of the main tornado. The next tornado was a weak tornado which touched down about 4 miles west of downtown Des Moines. The tornado did little damage, but did affect one house and several trees. The tornado was seen by a local television sky camera. A short time later, an F2 tornado touched down in Warren County and tracked into southeast Polk County. The track was over rural areas and damage from it was relatively minor. A more significant F3 tornado tracked from northern Lucas County, and weakened to an F2 as it moved across Warren, part of marion, and into Jasper County. One house was destroyed in Lucas County with the four people inside sustaining minor injuries. Once again, this tornado tracked across mostly rural areas, though it did hit a business and two homes in Jasper County and did $1,000,000 in damage. One person was injured in Jasper County. The last tornado touched down in Davis County at Bloomfield and tracked northeast into Wapello County with a maximum strength of F3. Damage in Davis County was over $500,000 as 64 homes and businesses were damaged in the Bloomfield area. To the northeast, the area of the tornado track was mostly rural and damage was limited to outbuildings for the most part. One farmstead reported severe damage near Floris in Davis County. The house was nearly levelled and several outbuildings were completely destroyed. Parts of the house and outbuildings were found as far as 5 miles away from the farmstead. As the storms moved north, high winds were produced over Story County east of Story City. High winds toppled a tractor semi-trailer truck east of Story City on Interstate 35, injuring the driver. Two cars and a truck were also blown off Interstate 35 in Hamilton County. Four people were injured. Two were taken to the hospital, treated, and released. Two were listed in serious condition, one with a neck fracture, the other with a shoulder fracture. The later incident appeared to be from the rear flank downdraft behind the storm and not the initial gust front. From the preliminary data, 178 homes and business were damaged or destroyed by the tornadic storms as well as countless outbuildings. There were several reports of livestock loss as well. It is truly amazing that there was no loss of life during this event and even more amazing is the fact that the injuries that did occur were all minor. Twenty counties in Iowa experienced serious damage from the storms of the day. Iowa Governor Vilsack declared several counties in Iowa disaster areas. These included Taylor, Union, Adams, and Adair Counties. High winds accompanied the storms as the moved through Appanoose County. A local gas station recorded an 81 MPH wind gust as the storms cut a half mile wide swath of destruction west of Moravia. There were numerous reports of cattle killed by the storms. Some were killed by the tornadoes and flying debris, others by lightning. Reports in Adair County, northwest of Fontanelle indicated about 25 head of cattle were struck by lightning shortly before a tornado moved through that area. As the area of storms that produced the high winds north of Ames in central Iowa moved north, they lost their punch. A few of the storms did remain quite strong however. As the area of thunderstorms moved through Cerro Gordo County, high winds blew down a 60 foot corn crib and did some other damage on a farm near Rockwell. | |||||||||||
| 31.8 | 1967-06-07 | 2 | 42°03'N / 93°37'W | 1.00 Mile | 100 Yards | 0 | 0 | 25K | 0 | Story | |
| 32.0 | 1961-04-23 | 3 | 42°02'N / 92°55'W | 42°04'N / 92°46'W | 7.40 Miles | 800 Yards | 0 | 6 | 2.5M | 0 | Marshall |
| 32.0 | 1962-05-28 | 2 | 41°10'N / 93°12'W | 41°18'N / 93°03'W | 11.70 Miles | 200 Yards | 0 | 0 | 250K | 0 | Marion |
| 33.4 | 1969-06-29 | 2 | 41°48'N / 92°36'W | 1.00 Mile | 250 Yards | 0 | 0 | 25K | 0 | Poweshiek | |
| 33.5 | 1964-06-22 | 2 | 41°36'N / 93°47'W | 41°39'N / 93°58'W | 9.70 Miles | 200 Yards | 0 | 0 | 250K | 0 | Dallas |
| 33.9 | 2008-05-30 | 2 | 41°13'N / 93°07'W | 41°15'N / 92°52'W | 12.00 Miles | 900 Yards | 0 | 10 | 750K | 25K | Marion |
| Brief Description: EVENT NARRATIVE: Several homes were damaged or destroyed, two mobile homes were destroyed. Considerable tree damage was reported. The EF2 damage occurred in the Attica area, along with 10 injuries. The tornado moved out of Marion County into Mahaska County. EPISODE NARRATIVE: A very unstable airmass moved into Iowa during the day on the 29th as a warm front lifted north into the state during the afternoon. Low pressure approached from the west, along with a cold front so that the triple point was near the western Iowa, eastern Nebraska area by late afternoon. Thunderstorms erupted quickly during the late afternoon and evening hours in the unstable airmass. By evening, the low level jet was in the 40 to 60 kt range, feeding moisture into the state and pushing precipitable water values to around 200% of normal, in the 1.5 to 1.8 inch range. MUCAPE reached 3000 to 3500 J/kg over western Iowa, with lifted indices in the -6 to -10 C. range. The freezing level was quite high, limiting the hail size somewhat with this event, at 14,300 feet. The available CAPE in the -10 to -30 C. layer of the atmosphere was in the 300 to 500 J/kg range. The DCAPE was between 800 and 1000 J/kg. The environment was highly sheared with 50 to 65 kts of shear available during the event. The LCL was also quite low, in the 750 to 1250 meter range. Thunderstorms erupted over western Iowa stretching into north central Iowa first. It did not take long for the storms to become severe with hail and high winds. Most of the hail reported was in the pea to marble size, with the larger stones in the nickel to quarter size range. The primary mode of severe weather was high winds and several tornadoes. The secondary, but significant threat, was heavy rainfall. A band of 3 to 5 inches of rain fell between U.S. Highway 30 and U.S. Highway 20 during the event. The heaviest rainfall total was in Greene County at Jefferson, with 5.90 inches. Tornadoes began to touch down in western Iowa in Crawford County with two brief touchdowns. One was west of Dow City, causing roof and shingle damage to a farmhouse there. The next was east of Denison where a barn roof was removed and a trailer house was destroyed. A tornado in Carroll County caused damage to 3 farmsteads southeast of Templeton. A machine shed was completely destroyed and numerous other buildings sustained damage. Trees also had substantial damage. Two tornadoes touched down in Calhoun County. One near Farnhamville, tore the roof off of a home and downed power lines. The second caused damage to trees, outbuildings, and power lines on four farmsteads. Farther south, a brief touchdown was reported in Dallas County in open fields west of Minburn. Another tornado touched down in Dallas County later on, west of Adel, and was on the ground for about 4 miles. A more substantial tornado touched down near Murray in Clarke County with one reported on the ground for about 9 miles. As the storms moved east, another tornado was on the ground for over 10 miles in Warren and Marion Counties. The most significant tornado occurred in Marion and Mahaska Counties where an EF2 tornado was on the ground for about 18 miles. Several homes were damaged along its path, two mobile homes were destroyed, and considerable damage was done to trees in the area. Up to 10 people were injured with this tornado, mainly in Attica. The official damage count from this tornado included 5 homes destroyed, 15 with major damage, and another 25 with minor damage. Many of the storms produced high winds with several reports of winds in the 65 to 75 MPH range. Considerable tree damage was reported and some structural damage, mainly outbuildings and shingle damage. Two cars were blown off of the road east of Manning by the high winds. Building debris was blown onto Highway D60 near Gowrie, causing a brief closure. High winds in Butler County blew down a machine shed and barn southwest of Aplington, very near to where an EF5 tornado struck just days before. Extensive damage was done to a farmstead there with some damage done to the house itself as well. Lightning struck a man in Carroll. The lightning bolt hit his driveway, blowing out a chunk of concrete out of the driveway and also injured the man. He was taken to hospital, treated, and released with minor injuries. Flooding became a significant issue after the heavy rainfall of the previous few days. Extensive river flooding occurred across the central third of the state. Record crests were recorded on the Iowa River at Marshalltown. | |||||||||||
| 34.1 | 2005-11-12 | 2 | 42°03'N / 93°38'W | 42°08'N / 93°36'W | 9.00 Miles | 100 Yards | 0 | 1 | 250K | 0 | Story |
| Brief Description: Tornado moved from Boone County into Story County. One minor injury occurred on the west side of Ames. A very intense weather system developed over the central U.S. during the day on the 12th. A strong upper level system moved through the area with mid and upper level winds in the 70 to 90 kt range. Low level winds of 35 to 50 kts transported moisture north into the system. High temperatures reached the mid 60s to low 70s, with dew point readings approaching 60 by late afternoon. A surface low developed over northern Kansas during the previous night and lifted northeast into eastern South Dakota during the afternoon of the 12th, then into central Minnesota as a 985 mb low by late evening. The atmosphere became quite unstable with CAPE values reaching 1000 J/kg by late afternoon. The Lifted Index values were in the -5 C. range. Being as it was in November, the freezing level was quite low during the event, in the 10,000 to 11,000 foot range. Though the soundings were quite unidirectional, there was plenty of shear with zero to 6 km shear values around 65 kts. Thunderstorms erupted during the afternoon in west central in to southwest Iowa. The storms became severe quite quickly. Initially the storms produce quarter to golf ball size hail, with 2 1/2 inch diameter hail falling in Dallas County. Hail up to baseball size fell in Greene County as well. The system transitioned into a tornadic system within an hour with several tornadoes touching down in the central sections of the state. At least 9 communities were hit by tornadoes and 65 homes damaged or destroyed. An 82 year old woman was killed in Stratford when the tornado demolished her home. In a 2 or 3 block area of downtown Woodward, at least 12 houses were totally destroyed. There was one minor injury in Ames, two serious injuries in the Woodward area, and three injuries in Stratford. Due to the extensive damage to property caused by the tornadoes, Iowa Governor Vilsack declared Boone, Story, Webster, Dallas and Hamilton Counties disaster areas. A long-lived tornado tracked through several counties across central Iowa during the late afternoon hours of Nov. 12, 2005. The tornado path is estimated at 27.5 miles long and between 100 and 150 yards wide along the damage path. Tornado (1) initially touched down just west of E Avenue (just south of Boxholm in northwest Boone county), one half mile south of Boone County Highway E18 at approximately 4:27 p.m as an F1 tornado. The tornado then tracked northeast across E Avenue, hitting a farm just north of E18, damaging the home and some out buildings. It also flipped over one pickup truck and killed two horses at this location. The tornado continued northeast, spreading debris across F Avenue just north of 125th Street as it maintained F1 intensity. Two additional homes were damaged with outbuildings destroyed as the tornado tracked northeast across G and H Avenues near 105th Avenue. It then intensified to an F2 tornado as it crossed the Boone/Webster county line. Another home was heavily damaged and a large outbuilding destroyed just north of the Boone/Webster county line. The tornado quickly moved northeast, crossing 390th Street and headed toward the Des Moines River, weakening to an F1 tornado. A continuous, but weak damage path was observed crossing the river as the tornado tracked across open farmland and land adjacent the Des Moines River. The tornado has been rated an F1 tornado during this time. After crossing County D64 in Webster county, the tornado struck another farm near 370th Street and Washington Avenue, damaging the residence and destroying a machine shed along with most of its contents. The tornado again intensified to an F2 at this location. The tornado then headed toward Stratford, crossing the Webster and Hamilton county line just west of County Road D54. The tornado entered Stratford at 4:46 p.m. on the west-central end of town, heavily damaging many homes. The tornado crossed the city park and then exited the city near the north-central portion of Stratford. Numerous homes were heavily damaged with one fatality. As the tornado left Stratford, it continued on a northeast track, lifting and dropping to the ground several times as an F0 and F1 tornado. It damaged three additional farms northeast of Stratford with the last damaged farm north of 320th Street and west of County Road R21 in Hamilton County. Tornado (2) touched down one mile west of Minburn in Dallas County according to the aerial survey. The tornado tracked northeast for about eight miles, producing F0-F1 damage before intensifying near Highway 141. The tornado produced F2 damage at a farm one mile southwest of Woodward, and continued to produce F2 damage through the south and east portions of Woodward. The tornado dissipated one mile northeast of Woodward. Severe houses slid off their foundations in Woodward, and a double-wide home was flipped upside down into the street. Total path length was 11 miles. Tornado (3) touched down in open fields one mile northwest of Madrid. It hit a home three miles north of Madrid on Highway 17, producing F1 damage. One other farm site sustained damage as the tornado moved northeast. The tornado dissipated after a six mile track. Tornado (4) started just west of Ames near the Highway 30 and Lincoln Way Split, according to the aerial survey. The tornado produced F1-F2 damage on the northwest fringe of Ames. It weakened as it moved northeast, before intensifying again and produced F2 damage to a farm site just south of Gilbert. F1 damage occurred as the tornado crossed highway 69. The tornado dissipated three miles south of Story City after a 10 mile track. Tornado (5) was a short-lived satellite tornado that was on the ground for 1.6 miles ending at the southwest edge of Story City. The aerial survey showed very minor damage. Tornado (6) developed one mile west of Roland and tracked across the extreme southeast corner of Hamilton county before entering Hardin county. The tornado produced damage up to F1 intensity to rural farm sites in far northern Story county and five miles south of Radcliffe in Hardin county. The KCCI-TV aerial survey indicated the track was nine miles in length. Tornado (7) was a brief touchdown just south of Williams in Hamilton County. No damage was found from this brief tornado and it is not shown here. Tornado (8) was briefly sighted near Blakesburg in Monroe County. The tornado produced minor damage to a farm building but was not surveyed. Tornado (9) touched down briefly north of Steamboat Rock in Hardin County. The tornado caused little damage. Tornado (10) was actually the first tornado of the day. It formed from the same supercell that eventually moved northeast into the Stratford area. The tornado caused little damage as it moved through fields south of the Scranton Area. Tornado (11) was a brief touchdown on the southwest edge of the Ames City limits. This tornado was from the same parent cell as the previous tornado that touched down in Ames, but was distinct. The tornado was weak and lifted lawn chairs and caused some shingle damage. This tornado was ANTICYCLONIC in nature. | |||||||||||
| 35.0 | 1965-09-16 | 2 | 42°07'N / 93°36'W | 0.50 Mile | 100 Yards | 0 | 0 | 25K | 0 | Story | |
| 35.6 | 1989-05-24 | 4 | 42°11'N / 93°27'W | 42°13'N / 93°13'W | 13.00 Miles | 150 Yards | 0 | 0 | 25.0M | 0 | Story |
| 35.6 | 1979-03-29 | 3 | 41°16'N / 93°47'W | 41°22'N / 93°38'W | 9.90 Miles | 500 Yards | 0 | 1 | 0K | 0 | Warren |
| 35.9 | 1998-06-29 | 2 | 41°52'N / 93°59'W | 41°46'N / 93°50'W | 10.50 Miles | 100 Yards | 0 | 2 | 500K | 20K | Dallas |
| Brief Description: A complex weather situation was set up over the central U.S. as a mesoscale convective system passed to the south of Iowa during the overnight hours and early morning of the 29th. Initially, the surface warm front was located to the south of this system. That was not actually the case aloft however. During the predawn hours the surface front surged north and by sunrise was located across northeast Nebraska across northern Iowa. The airmass was very unstable to the south of the front with dew point temperatures will in the 70s F. The initial development of thunderstorms took place during the early part of the day over northeast Nebraska. The storms became severe quickly as they moved and developed eastward into Iowa. By mid morning, the storms had formed a nearly east to west line. Storm relative inflow into the line was around 40 knots. The storms produced a variety of severe weather across Iowa. They initially moved east across the northern and central counties, but then began sinking sinking southeast. The dominant severe weather with the storms was extremely high winds. Damage was very widespread across the state. Winds in excess of 100 MPH were reported with one unofficial wind speed measured at 126 MPH in the town of Washington at 1405 CST. In one unusual story, high winds hit Mahaska County. Three miles south of New Sharon, a puppy was tied to its dog house which was picked up by the wind. The dog house and puppy were lifted over the top of a two car garage and a corn crib. Both were deposited in the farm yard. When found the dog house was upside down and the puppy, though scared, was fine. There were several tornadoes during the event. One of the longer track well defined tornadoes was the initial tornado. It was on the ground for about 11 miles as it swept across Crawford County. Several residences, outbuildings, grain bins, and trees were damaged along its path. Reports indicate that between 30 and 50 residences were damaged by this tornado. There were several small tornadoes in central Iowa. They had short tracks and only touched down briefly. One cut a mile long path east of Marshalltown through a corn field and a grove of trees. Another in Dallas County was on the ground through mostly open country for two miles. High winds were a major problem with these storms. Many places reported winds over 80 MPH with incredible tree damage and numerous buildings damaged or destroyed. At least 38 counties were declared disaster areas by the Federal Government due to the severe damage and flooding. A final total will not be available before publication deadlines, however preliminary data have been included. In the Des Moines County Warning Area these included: Wright, Franklin, Butler, Bremer, Hamilton, Hardin, Grundy, Crawford, Carroll, Greene, Boone, Story, Marshall, Audubon, Guthrie, Dallas, Polk, Jasper, Cass, Adair, Madison, Warren, Marion, Adams, and Taylor. One of the hardest hit Counties was Polk County. Damage appeared to be from straight line winds based on a storm survey that was done following the event. The damage occurred over the southwest semicircle of a large meso low in contact with the ground. Due to the rapid translational speed of 50 to 75 MPH, winds were enhanced on the southwest semicircle of the meso low. Smaller scale winds could have been embedded within this circulation as well. There was little evidence of small scale convergent tornadic damage, however aerial surveys did make some suggestion and eye witness accounts of sightings were quite numerous in the metro Des Moines area. All trees and debris were laid down to the south or southeast. The major damage swath as 3 to 7 miles wide northwest of Camp Dodge, with a widening into a full blown derecho after that. The event was born a few miles northwest of Perry, between Rippey and Berkley in southwest Boone County. The mile wide damage path expanded to over 3 miles by the time it reached full intensity near highway 169 between Woodward and Perry. The path continued through Granger, Camp Dodge, and Johnston. The path was nearly 7 miles wide near Granger. A second, smaller, meso low passed near Madrid, downing power lines. This meso low matured near Jester Park Golf Course, causing significant structural damage to houses. The two meso lows merged near the NWS Forecast Office in Johnston, with two miles of power poles snapped off between Johnston and Granger. Much of the damage along the most severe track was in the F1 intensity category, with speeds in the 75 to 110 MPH range. A few spots along the path, such as in the Granger and Camp Dodge area, sustained sufficient damage to justify F2 winds, 110 to 155 MPH. It appears a tornado or family of tornadoes touched down southeast of Berkley and moved southeast into the Pleasant Hill area just east of Des Moines. The track was intermittent, indicating either one tornado touching down occasionally, or one or more weak tornadoes rotating around the meso circulation. The worst effected metro areas were the Granger area, Johnston, and the northeast side of Des Moines proper. A duplex in Granger was flattened by the winds. There were several reports of roofs being ripped off of stores and houses in the metropolitan Des Moines area. Several small private planes were flipped at a small air field north of Des Moines. There were also several reports of semi-tractortrailer trucks being blown over on Interstate 35. Heavy construction equipment was overturned on Interstate 35/80 just north of Des Moines. Damage was extensive to the east side of Des Moines proper. To make matters worse, following the passage of the main line of thunderstorms, a second line of severe thunderstorms developed and moved across the same areas already hit. The storms were smaller, but did produce brief tornado touch downs and hail up to 2.5 inches in diameter. The second line of storms did eventually combine with the first and moved southeast across the rest of the state. Damage was widespread across the state and it will be months before final numbers are in. Estimates from Polk County alone are near $100 million in damage including cleanup. Totals were still being tallied at this writing, however a few include over $11 million in damage from initial claims in Johnston and $726,000 from West Des Moines just to city buildings and systems. West Des Moines was on the far west edge of the major damage however. In addition to the property damage, at least 125 people were injured during the storm. Most of the injuries were caused by flying debris and many were not serious. Fortunately there were no fatalities. Heavy damage was reported by MidAmerica Energy. On a state wide report, they indicated 200,000 homes were without electricity, effecting over 500,000 people, at one time during the storm. In the metropolitan Des Moines area, 100,000 homes were without electricity at the height of the storm. That number was reduced to around 25,000 36 hours later. The worst damaged areas were without power for 5 to 6 days. Heavy damage was also reported by local telephone and cable systems. In Polk County, the worst damage extended from the Camp Dodge area into the northeast parts of Des Moines. At least 462 homes in the metro Des Moines area sustained significant damage. Statewide, 80 homes were destroyed, 559 sustained severe damage, with 1416 others receiving moderate damage. In the Camp Dodge area, 80 to 90 percent of the brick buildings were damaged with the roofs removed from many of them. Lightning from the storms struck the WSR-88D in the midst of the storm. The radar was taken out of service for more than 24 hours because of this. In addition to the severe weather, flooding quickly became a problem. Iowa soil was nearly saturated as the weather pattern had been very wet for six weeks previous. Although rainfall was not extreme, one to three inches of rain fell over a several county area. This caused widespread urban flooding across north central into central Iowa, though damage from the flooding was not serious. Crop damage was very difficult to determine and will not likely be clear until the fall harvest. Reports from some of the local extension agents say damage to the corn ranged up to 75% destroyed in areas with the highest wind, such as the swath that went through central Iowa in association with the tornado there. No doubt losses will be in the hundreds of thousands of dollars if not in the millions. Accounts of damage were of course too numerous to document here as the areal extent of the storms was very large. Countless reports of parts of crop fields being flattened were received. Semi-tractortrailer trucks were overturned by the high winds both in the Des Moines metro area as well as in Newton. Trees were found on houses over a large part of the state. One news reported wrote "there is not a power pole standing between Fort Dodge and Oskaloosa". Though not figuratively true, this statement does point out the extensive damage that occurred with these storms.l | |||||||||||
| 36.2 | 1972-06-05 | 2 | 41°13'N / 93°00'W | 41°11'N / 92°58'W | 1.90 Miles | 200 Yards | 0 | 0 | 25K | 0 | Marion |
| 36.2 | 1976-06-13 | 2 | 42°07'N / 93°39'W | 42°08'N / 93°36'W | 1.30 Miles | 200 Yards | 0 | 0 | 25K | 0 | Story |
| 36.3 | 1976-06-13 | 5 | 41°56'N / 93°52'W | 42°06'N / 93°42'W | 14.00 Miles | 880 Yards | 0 | 9 | 25.0M | 0 | Boone |
| 36.4 | 1989-05-24 | 4 | 42°13'N / 93°13'W | 42°12'N / 93°00'W | 12.50 Miles | 150 Yards | 0 | 0 | 25.0M | 0 | Hardin |
| 36.8 | 1953-06-27 | 2 | 41°24'N / 92°36'W | 41°20'N / 92°44'W | 7.80 Miles | 100 Yards | 0 | 1 | 3K | 0 | Mahaska |
| 36.8 | 1999-04-08 | 3 | 41°31'N / 94°01'W | 41°46'N / 93°52'W | 19.00 Miles | 1000 Yards | 0 | 0 | 40K | 0 | Dallas |
| Brief Description: As mentioned in the narrative above, an intense low pressure formed to the southwest of Iowa. The low tracked northeast and lifted into eastern Nebraska. Ahead of the low, a strong low level jet of around 60 knots continued through the day. A nearly stationary frontal boundary extended east from the low. It lifted into southeast Nebraska during the day, but made little progress into southern Iowa. Lines of thunderstorms formed along the boundary through the day and lifted north rapidly. These storms were elevated in nature and as a result produced most of their severe weather in the form of hail. As the day unfolded, a sharp dry line was clearly evident on the satellite as early as 1600 UTC across Kansas. This line raced east during the day. By afternoon, a speed max had rotated around the upper low to the southwest with wind speeds measured by the Lathrop wind profiler at 100 knots at 500 mb by mid afternoon. Jet stream winds were in excess of 120 knots at the same time. Combined with the dynamic situation mentioned above, considerable moisture convergence took place near the triple point between the warm front and the dry line. Surface dew points pooled into to the mid 60s to even a few 70 degree F. dew point readings over northwest Missouri, southeast Nebraska, and southwest Iowa. Meanwhile, dew points fell into the upper 20s over northeast Kansas and south central Nebraska behind the dry line, with teens over central and south central Kansas. Thunderstorms erupted along the dry line by mid day and advanced east through the afternoon. Low level helicity values topped out between 500 and 600 (m/s)**2 just before the first tornadoes formed. Most of the storms in the warm sector became tornadic quickly. The northern limit of the tornado tracks extended about 10 miles or so north of the warm front. Tracks became intermittent very quickly as soon as the storms crossed the surface warm front due to the layer of very cold air just north of the front. Surface temperatures on the cold side of the front were only in the upper 40s to mid 50s. The entire day was very active. Initially, warm air advection thunderstorms produced hail at many locations of central and northern Iowa. Most of is was just below severe levels however. The activity that developed during the afternoon was a combination of warm air advection and the approach of the dryline. At the beginning of the event, the main weather feature was in the form of hail. There were numerous reports of hail three quarters to one and three quarters inch in diameter. The largest hail fell in Guthrie and Dallas Counties with reports of golf ball size hail. One of the storms in the initial wave of afternoon activity became stronger as it moved into southern Story County. Initially, high winds of 60 MPH or more swept through Sheldahl area of Boone County. Greene County was also affected by high winds from the storms. A tornado dropped out of the storm as it moved into the Slater area and was on the ground for about 2 miles. Initial estimates showed 44 homes and businesses damaged in Story County, one was destroyed with major damage to another. Thirty six homes and four businesses were damaged in the town of Slater. Two people were injured during the passage of the tornado. One of the injuries involved a 70 year old man who was picked up by the tornadoes winds and thrown about 10 feet before he latched on to something. His shoulder was dislocated and he required 6 stitches due to his injuries in his hand. High winds northeast of Slater knocked several cars of a Burlington Northern freight train off the tracks after they were blown more than one quarter mile down the track. It was not possible to determine of the cars were knocked off by the tornado or high winds however. This band of storms continue to race and develop northeast through the afternoon. Damage became more sporadic, however high winds occurred as far northeast as Hardin County, with 70 MPH winds reported near New Providence. Hail reports came in from as far northeast as Grundy and Black Hawk Counties, though it was only three quarters of an inch in diameter. Attention then shifted to the tornadic storms that formed near the dry line. During the afternoon, six more tornadoes touched down in Iowa, several of which were long track tornadoes. The first touched down in Taylor County and tracked through Adams, Cass, and Adair Counties. This tornado had was an F4 intensity tornado in parts of Adair and Adams Counties. Damage was extensive with $1,000,000 damage reported in both Adams and Adair Counties. Entire farmsteads were swept clean by the tornado. At one time this tornado was a mile wide wedge with a damage path nearly two miles wide due to the circulation around the tornado. Eyewitness reports indicated that the tornado split into two distinct tornadoes at times, similar to what occurred with the intense F4 tornado in Adair County of 27 May 1995. One of the farmsteads hit near Nodaway was levelled. Reports indicated that a check was blown from the house nearly 100 miles and was found in the town of Jefferson in Greene County. Other checks and papers were found strewn along the path, stretching from Jefferson all the way back to northwest Taylor County. In Adair County, one account indicated pieces of sheet metal from one farm was lifted and deposited six miles away from the farm. Two people were injured by this tornado, one in Adams County with the other in Adair County. One of the injuries Adair County was serious as a man suffered a broken back when the tornado lifted his semi-tractortrailer truck from the Interstate and threw it into a nearby field. The other injuries from this tornado were minor enough that the people were taken to the hospital, treated, and released. There was one account of a horse being picked up by the tornado. It was lifted into the air and thrown through a stand of pine trees 40 feet high. The horse suffered serious injuries and required significant medical attention do to lacerations. The horse amazingly did survive against all odds, though was said would likely lose sight in one eye. The next tornado touched down in Union County and tracked across Madison and Dallas Counties. This tornado had an F4 strength in Union and decreased to a strong F2 in Madison Counties before intensifying again to near F3 strength as it headed into Dallas County. Damage in Union County was around $2,000,000, and around $350,000 in Madison County. There was one person injured by this tornado in Union County. In an amazing account, the Union County Sheriff reported watching as the tornado lifted the car in front of him 35 feet in the air and throwing it 250 feet. The driver was inside during this time and came out of the situation uninjured. Five coal cars were knocked off the tracks in Union County by the tornado as well. This tornado also had a double structure. From eye witness accounts, which also can be shown on Doppler radar imagery, suggest a small rope like tornado passed through the Twelve Mile Lake area shortly before the passage of the main tornado. The next tornado was a weak tornado which touched down about 4 miles west of downtown Des Moines. The tornado did little damage, but did affect one house and several trees. The tornado was seen by a local television sky camera. A short time later, an F2 tornado touched down in Warren County and tracked into southeast Polk County. The track was over rural areas and damage from it was relatively minor. A more significant F3 tornado tracked from northern Lucas County, and weakened to an F2 as it moved across Warren, part of marion, and into Jasper County. One house was destroyed in Lucas County with the four people inside sustaining minor injuries. Once again, this tornado tracked across mostly rural areas, though it did hit a business and two homes in Jasper County and did $1,000,000 in damage. One person was injured in Jasper County. The last tornado touched down in Davis County at Bloomfield and tracked northeast into Wapello County with a maximum strength of F3. Damage in Davis County was over $500,000 as 64 homes and businesses were damaged in the Bloomfield area. To the northeast, the area of the tornado track was mostly rural and damage was limited to outbuildings for the most part. One farmstead reported severe damage near Floris in Davis County. The house was nearly levelled and several outbuildings were completely destroyed. Parts of the house and outbuildings were found as far as 5 miles away from the farmstead. As the storms moved north, high winds were produced over Story County east of Story City. High winds toppled a tractor semi-trailer truck east of Story City on Interstate 35, injuring the driver. Two cars and a truck were also blown off Interstate 35 in Hamilton County. Four people were injured. Two were taken to the hospital, treated, and released. Two were listed in serious condition, one with a neck fracture, the other with a shoulder fracture. The later incident appeared to be from the rear flank downdraft behind the storm and not the initial gust front. From the preliminary data, 178 homes and business were damaged or destroyed by the tornadic storms as well as countless outbuildings. There were several reports of livestock loss as well. It is truly amazing that there was no loss of life during this event and even more amazing is the fact that the injuries that did occur were all minor. Twenty counties in Iowa experienced serious damage from the storms of the day. Iowa Governor Vilsack declared several counties in Iowa disaster areas. These included Taylor, Union, Adams, and Adair Counties. High winds accompanied the storms as the moved through Appanoose County. A local gas station recorded an 81 MPH wind gust as the storms cut a half mile wide swath of destruction west of Moravia. There were numerous reports of cattle killed by the storms. Some were killed by the tornadoes and flying debris, others by lightning. Reports in Adair County, northwest of Fontanelle indicated about 25 head of cattle were struck by lightning shortly before a tornado moved through that area. As the area of storms that produced the high winds north of Ames in central Iowa moved north, they lost their punch. A few of the storms did remain quite strong however. As the area of thunderstorms moved through Cerro Gordo County, high winds blew down a 60 foot corn crib and did some other damage on a farm near Rockwell. | |||||||||||
| 36.8 | 1978-06-26 | 2 | 41°35'N / 92°32'W | 0.70 Mile | 100 Yards | 0 | 1 | 2.5M | 0 | Poweshiek | |
| 36.9 | 1976-06-13 | 3 | 42°05'N / 93°44'W | 42°05'N / 93°42'W | 0 | 0 | 25K | 0 | Boone | ||
| 37.9 | 1976-06-13 | 5 | 42°06'N / 93°42'W | 42°11'N / 93°36'W | 7.30 Miles | 880 Yards | 0 | 0 | 0K | 0 | Story |
| 38.2 | 1976-06-13 | 2 | 42°02'N / 93°48'W | 42°06'N / 93°45'W | 4.50 Miles | 100 Yards | 0 | 0 | 0K | 0 | Boone |
| 38.2 | 1965-05-25 | 2 | 41°20'N / 92°40'W | 2.00 Miles | 300 Yards | 0 | 0 | 3K | 0 | Mahaska | |
| 38.4 | 1976-04-14 | 2 | 41°46'N / 94°01'W | 41°48'N / 93°55'W | 4.90 Miles | 67 Yards | 0 | 0 | 0K | 0 | Dallas |
| 38.5 | 1953-03-21 | 2 | 41°53'N / 92°37'W | 42°03'N / 92°33'W | 11.70 Miles | 100 Yards | 0 | 0 | 25K | 0 | Tama |
| 38.6 | 1955-04-04 | 2 | 41°46'N / 93°59'W | 41°56'N / 93°55'W | 11.60 Miles | 440 Yards | 0 | 0 | 25K | 0 | Dallas |
| 39.1 | 2005-11-12 | 2 | 41°53'N / 93°58'W | 41°54'N / 93°55'W | 1.00 Mile | 100 Yards | 0 | 2 | 750K | 0 | Boone |
| Brief Description: Tornado moved from Dallas County into Boone County. Two injuries occurred in Woodward. A very intense weather system developed over the central U.S. during the day on the 12th. A strong upper level system moved through the area with mid and upper level winds in the 70 to 90 kt range. Low level winds of 35 to 50 kts transported moisture north into the system. High temperatures reached the mid 60s to low 70s, with dew point readings approaching 60 by late afternoon. A surface low developed over northern Kansas during the previous night and lifted northeast into eastern South Dakota during the afternoon of the 12th, then into central Minnesota as a 985 mb low by late evening. The atmosphere became quite unstable with CAPE values reaching 1000 J/kg by late afternoon. The Lifted Index values were in the -5 C. range. Being as it was in November, the freezing level was quite low during the event, in the 10,000 to 11,000 foot range. Though the soundings were quite unidirectional, there was plenty of shear with zero to 6 km shear values around 65 kts. Thunderstorms erupted during the afternoon in west central in to southwest Iowa. The storms became severe quite quickly. Initially the storms produce quarter to golf ball size hail, with 2 1/2 inch diameter hail falling in Dallas County. Hail up to baseball size fell in Greene County as well. The system transitioned into a tornadic system within an hour with several tornadoes touching down in the central sections of the state. At least 9 communities were hit by tornadoes and 65 homes damaged or destroyed. An 82 year old woman was killed in Stratford when the tornado demolished her home. In a 2 or 3 block area of downtown Woodward, at least 12 houses were totally destroyed. There was one minor injury in Ames, two serious injuries in the Woodward area, and three injuries in Stratford. Due to the extensive damage to property caused by the tornadoes, Iowa Governor Vilsack declared Boone, Story, Webster, Dallas and Hamilton Counties disaster areas. A long-lived tornado tracked through several counties across central Iowa during the late afternoon hours of Nov. 12, 2005. The tornado path is estimated at 27.5 miles long and between 100 and 150 yards wide along the damage path. Tornado (1) initially touched down just west of E Avenue (just south of Boxholm in northwest Boone county), one half mile south of Boone County Highway E18 at approximately 4:27 p.m as an F1 tornado. The tornado then tracked northeast across E Avenue, hitting a farm just north of E18, damaging the home and some out buildings. It also flipped over one pickup truck and killed two horses at this location. The tornado continued northeast, spreading debris across F Avenue just north of 125th Street as it maintained F1 intensity. Two additional homes were damaged with outbuildings destroyed as the tornado tracked northeast across G and H Avenues near 105th Avenue. It then intensified to an F2 tornado as it crossed the Boone/Webster county line. Another home was heavily damaged and a large outbuilding destroyed just north of the Boone/Webster county line. The tornado quickly moved northeast, crossing 390th Street and headed toward the Des Moines River, weakening to an F1 tornado. A continuous, but weak damage path was observed crossing the river as the tornado tracked across open farmland and land adjacent the Des Moines River. The tornado has been rated an F1 tornado during this time. After crossing County D64 in Webster county, the tornado struck another farm near 370th Street and Washington Avenue, damaging the residence and destroying a machine shed along with most of its contents. The tornado again intensified to an F2 at this location. The tornado then headed toward Stratford, crossing the Webster and Hamilton county line just west of County Road D54. The tornado entered Stratford at 4:46 p.m. on the west-central end of town, heavily damaging many homes. The tornado crossed the city park and then exited the city near the north-central portion of Stratford. Numerous homes were heavily damaged with one fatality. As the tornado left Stratford, it continued on a northeast track, lifting and dropping to the ground several times as an F0 and F1 tornado. It damaged three additional farms northeast of Stratford with the last damaged farm north of 320th Street and west of County Road R21 in Hamilton County. Tornado (2) touched down one mile west of Minburn in Dallas County according to the aerial survey. The tornado tracked northeast for about eight miles, producing F0-F1 damage before intensifying near Highway 141. The tornado produced F2 damage at a farm one mile southwest of Woodward, and continued to produce F2 damage through the south and east portions of Woodward. The tornado dissipated one mile northeast of Woodward. Severe houses slid off their foundations in Woodward, and a double-wide home was flipped upside down into the street. Total path length was 11 miles. Tornado (3) touched down in open fields one mile northwest of Madrid. It hit a home three miles north of Madrid on Highway 17, producing F1 damage. One other farm site sustained damage as the tornado moved northeast. The tornado dissipated after a six mile track. Tornado (4) started just west of Ames near the Highway 30 and Lincoln Way Split, according to the aerial survey. The tornado produced F1-F2 damage on the northwest fringe of Ames. It weakened as it moved northeast, before intensifying again and produced F2 damage to a farm site just south of Gilbert. F1 damage occurred as the tornado crossed highway 69. The tornado dissipated three miles south of Story City after a 10 mile track. Tornado (5) was a short-lived satellite tornado that was on the ground for 1.6 miles ending at the southwest edge of Story City. The aerial survey showed very minor damage. Tornado (6) developed one mile west of Roland and tracked across the extreme southeast corner of Hamilton county before entering Hardin county. The tornado produced damage up to F1 intensity to rural farm sites in far northern Story county and five miles south of Radcliffe in Hardin county. The KCCI-TV aerial survey indicated the track was nine miles in length. Tornado (7) was a brief touchdown just south of Williams in Hamilton County. No damage was found from this brief tornado and it is not shown here. Tornado (8) was briefly sighted near Blakesburg in Monroe County. The tornado produced minor damage to a farm building but was not surveyed. Tornado (9) touched down briefly north of Steamboat Rock in Hardin County. The tornado caused little damage. Tornado (10) was actually the first tornado of the day. It formed from the same supercell that eventually moved northeast into the Stratford area. The tornado caused little damage as it moved through fields south of the Scranton Area. Tornado (11) was a brief touchdown on the southwest edge of the Ames City limits. This tornado was from the same parent cell as the previous tornado that touched down in Ames, but was distinct. The tornado was weak and lifted lawn chairs and caused some shingle damage. This tornado was ANTICYCLONIC in nature. | |||||||||||
| 39.2 | 1989-05-24 | 4 | 42°12'N / 93°00'W | 42°11'N / 92°45'W | 13.50 Miles | 150 Yards | 0 | 0 | 25.0M | 0 | Marshall |
| 39.4 | 1953-05-20 | 3 | 42°09'N / 93°42'W | 42°18'N / 93°18'W | 22.70 Miles | 400 Yards | 1 | 0 | 0K | 0 | Story |
| 40.1 | 1989-05-30 | 4 | 42°17'N / 93°10'W | 42°14'N / 92°59'W | 9.00 Miles | 200 Yards | 0 | 3 | 2.5M | 0 | Hardin |
| 40.9 | 1989-05-30 | 4 | 42°14'N / 92°59'W | 42°16'N / 92°58'W | 2.00 Miles | 200 Yards | 0 | 0 | 2.5M | 0 | Grundy |
| 41.3 | 1989-05-24 | 4 | 42°14'N / 93°49'W | 42°11'N / 93°27'W | 19.00 Miles | 150 Yards | 0 | 0 | 25.0M | 0 | Hamilton |
| 41.6 | 2001-05-10 | 2 | 42°15'N / 92°55'W | 42°14'N / 92°54'W | 1.70 Miles | 200 Yards | 0 | 0 | 150K | 0 | Grundy |
| Brief Description: Most in open country. One barn hit and destroyed. A cold front frontal system located to the northwest of Iowa began to sink southeast into the state during the late afternoon of the 10th. This was in fact the same cold front that set off the thunderstorm activity the previous night. The atmosphere had become quite unstable by the late afternoon with temperatures in the 80s and dew point temperature in the low to mid 60s. CAPE values were in the 2000 to 3500 J/kg range. Thunderstorms erupted during the mid afternoon hours over the north central counties of the state. These storms produced hail of one to one and one half inches in diameter. The instability of the atmosphere, combined with a favorable sheer profile, contributed to the rather quick development of tornadic supercells. The first tornado touched down in Greene County. This tornado touched down briefly and did little damage. As the afternoon progressed, the hail became larger with several reports of hail up to golf ball size from central Iowa east into the east central counties. Some of the largest hail occurred southwest of State Center in Marshall County. Baseball size hail pelted the area, causing considerable damage. One supercell produced a family of at least four tornadoes in the Grundy County area. It is very fortunate that the tornadoes from this storm did not hit within a populated area. Two of the tornadoes were fairly large. At one point, the strongest tornado was about one half mile wide based on reports from a respectable storm chaser. This tornado tracked south through eastern Grundy County and crossed into Tama County. One barn was destroyed by the larger tornado, with a house damaged by the second strong tornado. Miraculously, though the first tornado totally destroyed the barn on a farm near Conrad, none of the animals inside were injured. In fact, it was reported that the livestock appeared to be enjoying their newfound freedom as they wandered the fields at the farm. There were reports of several small tornadoes touching down in central Iowa, however they were little more than brief touchdowns. As the event progressed into the early evening hours, the thunderstorms too on a more multi-cellular structure. The large cluster of storms lost their tornadic characteristic and returned to large hail producers. Hail from three quarter inch to one and three quarter inch was common for the next several hours as the entire area moved southeast slowly. By the mid evening hours the storms began to weaken. As they did, a few reports of winds of 60 to 70 MPH were received. In addition to the wind and hail, the storms produced locally heavy rainfall. Flash flooding was also a problem with this event. The cluster of storms that dropped the tornadoes in Grundy County during the late afternoon hours caused flash flooding in the south part of the county. Rainfall near Conrad was between 2.5 and 5 inches in under two hours time. This flooded roads with some of the state roads in the south part of the county under water. The water receded fairly quickly. A merger of cells took place over Monroe County during the mid evening hours. This resulted in very heavy rainfall in the area with reports of up to 4 inches received. Flash flooding resulted with numerous roads being closed by overflowing creeks by the mid to late evening hours. | |||||||||||
| 41.6 | 1965-06-27 | 2 | 42°03'N / 92°35'W | 0 | 0 | 3K | 0 | Tama | |||
| 41.7 | 1991-03-22 | 2 | 42°16'N / 93°00'W | 42°16'N / 92°59'W | 1.00 Mile | 50 Yards | 0 | 0 | 250K | 0 | Hardin |
| 42.0 | 1956-08-18 | 2 | 41°23'N / 92°36'W | 41°28'N / 92°24'W | 11.50 Miles | 33 Yards | 0 | 0 | 25K | 0 | Mahaska |
| 42.1 | 1966-04-19 | 3 | 41°52'N / 92°42'W | 42°02'N / 92°17'W | 24.10 Miles | 400 Yards | 0 | 4 | 250K | 0 | Tama |
| 42.3 | 1999-04-08 | 3 | 41°04'N / 93°31'W | 41°09'N / 93°28'W | 4.50 Miles | 120 Yards | 0 | 4 | 250K | 0 | Lucas |
| Brief Description: As mentioned in the narrative above, an intense low pressure formed to the southwest of Iowa. The low tracked northeast and lifted into eastern Nebraska. Ahead of the low, a strong low level jet of around 60 knots continued through the day. A nearly stationary frontal boundary extended east from the low. It lifted into southeast Nebraska during the day, but made little progress into southern Iowa. Lines of thunderstorms formed along the boundary through the day and lifted north rapidly. These storms were elevated in nature and as a result produced most of their severe weather in the form of hail. As the day unfolded, a sharp dry line was clearly evident on the satellite as early as 1600 UTC across Kansas. This line raced east during the day. By afternoon, a speed max had rotated around the upper low to the southwest with wind speeds measured by the Lathrop wind profiler at 100 knots at 500 mb by mid afternoon. Jet stream winds were in excess of 120 knots at the same time. Combined with the dynamic situation mentioned above, considerable moisture convergence took place near the triple point between the warm front and the dry line. Surface dew points pooled into to the mid 60s to even a few 70 degree F. dew point readings over northwest Missouri, southeast Nebraska, and southwest Iowa. Meanwhile, dew points fell into the upper 20s over northeast Kansas and south central Nebraska behind the dry line, with teens over central and south central Kansas. Thunderstorms erupted along the dry line by mid day and advanced east through the afternoon. Low level helicity values topped out between 500 and 600 (m/s)**2 just before the first tornadoes formed. Most of the storms in the warm sector became tornadic quickly. The northern limit of the tornado tracks extended about 10 miles or so north of the warm front. Tracks became intermittent very quickly as soon as the storms crossed the surface warm front due to the layer of very cold air just north of the front. Surface temperatures on the cold side of the front were only in the upper 40s to mid 50s. The entire day was very active. Initially, warm air advection thunderstorms produced hail at many locations of central and northern Iowa. Most of is was just below severe levels however. The activity that developed during the afternoon was a combination of warm air advection and the approach of the dryline. At the beginning of the event, the main weather feature was in the form of hail. There were numerous reports of hail three quarters to one and three quarters inch in diameter. The largest hail fell in Guthrie and Dallas Counties with reports of golf ball size hail. One of the storms in the initial wave of afternoon activity became stronger as it moved into southern Story County. Initially, high winds of 60 MPH or more swept through Sheldahl area of Boone County. Greene County was also affected by high winds from the storms. A tornado dropped out of the storm as it moved into the Slater area and was on the ground for about 2 miles. Initial estimates showed 44 homes and businesses damaged in Story County, one was destroyed with major damage to another. Thirty six homes and four businesses were damaged in the town of Slater. Two people were injured during the passage of the tornado. One of the injuries involved a 70 year old man who was picked up by the tornadoes winds and thrown about 10 feet before he latched on to something. His shoulder was dislocated and he required 6 stitches due to his injuries in his hand. High winds northeast of Slater knocked several cars of a Burlington Northern freight train off the tracks after they were blown more than one quarter mile down the track. It was not possible to determine of the cars were knocked off by the tornado or high winds however. This band of storms continue to race and develop northeast through the afternoon. Damage became more sporadic, however high winds occurred as far northeast as Hardin County, with 70 MPH winds reported near New Providence. Hail reports came in from as far northeast as Grundy and Black Hawk Counties, though it was only three quarters of an inch in diameter. Attention then shifted to the tornadic storms that formed near the dry line. During the afternoon, six more tornadoes touched down in Iowa, several of which were long track tornadoes. The first touched down in Taylor County and tracked through Adams, Cass, and Adair Counties. This tornado had was an F4 intensity tornado in parts of Adair and Adams Counties. Damage was extensive with $1,000,000 damage reported in both Adams and Adair Counties. Entire farmsteads were swept clean by the tornado. At one time this tornado was a mile wide wedge with a damage path nearly two miles wide due to the circulation around the tornado. Eyewitness reports indicated that the tornado split into two distinct tornadoes at times, similar to what occurred with the intense F4 tornado in Adair County of 27 May 1995. One of the farmsteads hit near Nodaway was levelled. Reports indicated that a check was blown from the house nearly 100 miles and was found in the town of Jefferson in Greene County. Other checks and papers were found strewn along the path, stretching from Jefferson all the way back to northwest Taylor County. In Adair County, one account indicated pieces of sheet metal from one farm was lifted and deposited six miles away from the farm. Two people were injured by this tornado, one in Adams County with the other in Adair County. One of the injuries Adair County was serious as a man suffered a broken back when the tornado lifted his semi-tractortrailer truck from the Interstate and threw it into a nearby field. The other injuries from this tornado were minor enough that the people were taken to the hospital, treated, and released. There was one account of a horse being picked up by the tornado. It was lifted into the air and thrown through a stand of pine trees 40 feet high. The horse suffered serious injuries and required significant medical attention do to lacerations. The horse amazingly did survive against all odds, though was said would likely lose sight in one eye. The next tornado touched down in Union County and tracked across Madison and Dallas Counties. This tornado had an F4 strength in Union and decreased to a strong F2 in Madison Counties before intensifying again to near F3 strength as it headed into Dallas County. Damage in Union County was around $2,000,000, and around $350,000 in Madison County. There was one person injured by this tornado in Union County. In an amazing account, the Union County Sheriff reported watching as the tornado lifted the car in front of him 35 feet in the air and throwing it 250 feet. The driver was inside during this time and came out of the situation uninjured. Five coal cars were knocked off the tracks in Union County by the tornado as well. This tornado also had a double structure. From eye witness accounts, which also can be shown on Doppler radar imagery, suggest a small rope like tornado passed through the Twelve Mile Lake area shortly before the passage of the main tornado. The next tornado was a weak tornado which touched down about 4 miles west of downtown Des Moines. The tornado did little damage, but did affect one house and several trees. The tornado was seen by a local television sky camera. A short time later, an F2 tornado touched down in Warren County and tracked into southeast Polk County. The track was over rural areas and damage from it was relatively minor. A more significant F3 tornado tracked from northern Lucas County, and weakened to an F2 as it moved across Warren, part of marion, and into Jasper County. One house was destroyed in Lucas County with the four people inside sustaining minor injuries. Once again, this tornado tracked across mostly rural areas, though it did hit a business and two homes in Jasper County and did $1,000,000 in damage. One person was injured in Jasper County. The last tornado touched down in Davis County at Bloomfield and tracked northeast into Wapello County with a maximum strength of F3. Damage in Davis County was over $500,000 as 64 homes and businesses were damaged in the Bloomfield area. To the northeast, the area of the tornado track was mostly rural and damage was limited to outbuildings for the most part. One farmstead reported severe damage near Floris in Davis County. The house was nearly levelled and several outbuildings were completely destroyed. Parts of the house and outbuildings were found as far as 5 miles away from the farmstead. As the storms moved north, high winds were produced over Story County east of Story City. High winds toppled a tractor semi-trailer truck east of Story City on Interstate 35, injuring the driver. Two cars and a truck were also blown off Interstate 35 in Hamilton County. Four people were injured. Two were taken to the hospital, treated, and released. Two were listed in serious condition, one with a neck fracture, the other with a shoulder fracture. The later incident appeared to be from the rear flank downdraft behind the storm and not the initial gust front. From the preliminary data, 178 homes and business were damaged or destroyed by the tornadic storms as well as countless outbuildings. There were several reports of livestock loss as well. It is truly amazing that there was no loss of life during this event and even more amazing is the fact that the injuries that did occur were all minor. Twenty counties in Iowa experienced serious damage from the storms of the day. Iowa Governor Vilsack declared several counties in Iowa disaster areas. These included Taylor, Union, Adams, and Adair Counties. High winds accompanied the storms as the moved through Appanoose County. A local gas station recorded an 81 MPH wind gust as the storms cut a half mile wide swath of destruction west of Moravia. There were numerous reports of cattle killed by the storms. Some were killed by the tornadoes and flying debris, others by lightning. Reports in Adair County, northwest of Fontanelle indicated about 25 head of cattle were struck by lightning shortly before a tornado moved through that area. As the area of storms that produced the high winds north of Ames in central Iowa moved north, they lost their punch. A few of the storms did remain quite strong however. As the area of thunderstorms moved through Cerro Gordo County, high winds blew down a 60 foot corn crib and did some other damage on a farm near Rockwell. | |||||||||||
| 42.3 | 1964-07-07 | 2 | 42°10'N / 93°45'W | 2.00 Miles | 100 Yards | 0 | 0 | 25K | 0 | Boone | |
| 42.4 | 1953-05-10 | 2 | 41°53'N / 92°27'W | 0 | 0 | 25K | 0 | Tama | |||
| 42.4 | 1969-06-29 | 2 | 42°04'N / 93°53'W | 0 | 0 | 25K | 0 | Boone | |||
| 42.5 | 1966-06-11 | 2 | 42°05'N / 93°52'W | 2.00 Miles | 200 Yards | 0 | 0 | 25K | 0 | Boone | |
| 42.5 | 2005-11-12 | 2 | 41°46'N / 94°04'W | 41°51'N / 94°01'W | 12.00 Miles | 100 Yards | 0 | 0 | 2.5M | 0 | Dallas |
| Brief Description: Tornado touched down in Dallas County and moved into Boone County. A very intense weather system developed over the central U.S. during the day on the 12th. A strong upper level system moved through the area with mid and upper level winds in the 70 to 90 kt range. Low level winds of 35 to 50 kts transported moisture north into the system. High temperatures reached the mid 60s to low 70s, with dew point readings approaching 60 by late afternoon. A surface low developed over northern Kansas during the previous night and lifted northeast into eastern South Dakota during the afternoon of the 12th, then into central Minnesota as a 985 mb low by late evening. The atmosphere became quite unstable with CAPE values reaching 1000 J/kg by late afternoon. The Lifted Index values were in the -5 C. range. Being as it was in November, the freezing level was quite low during the event, in the 10,000 to 11,000 foot range. Though the soundings were quite unidirectional, there was plenty of shear with zero to 6 km shear values around 65 kts. Thunderstorms erupted during the afternoon in west central in to southwest Iowa. The storms became severe quite quickly. Initially the storms produce quarter to golf ball size hail, with 2 1/2 inch diameter hail falling in Dallas County. Hail up to baseball size fell in Greene County as well. The system transitioned into a tornadic system within an hour with several tornadoes touching down in the central sections of the state. At least 9 communities were hit by tornadoes and 65 homes damaged or destroyed. An 82 year old woman was killed in Stratford when the tornado demolished her home. In a 2 or 3 block area of downtown Woodward, at least 12 houses were totally destroyed. There was one minor injury in Ames, two serious injuries in the Woodward area, and three injuries in Stratford. Due to the extensive damage to property caused by the tornadoes, Iowa Governor Vilsack declared Boone, Story, Webster, Dallas and Hamilton Counties disaster areas. A long-lived tornado tracked through several counties across central Iowa during the late afternoon hours of Nov. 12, 2005. The tornado path is estimated at 27.5 miles long and between 100 and 150 yards wide along the damage path. Tornado (1) initially touched down just west of E Avenue (just south of Boxholm in northwest Boone county), one half mile south of Boone County Highway E18 at approximately 4:27 p.m as an F1 tornado. The tornado then tracked northeast across E Avenue, hitting a farm just north of E18, damaging the home and some out buildings. It also flipped over one pickup truck and killed two horses at this location. The tornado continued northeast, spreading debris across F Avenue just north of 125th Street as it maintained F1 intensity. Two additional homes were damaged with outbuildings destroyed as the tornado tracked northeast across G and H Avenues near 105th Avenue. It then intensified to an F2 tornado as it crossed the Boone/Webster county line. Another home was heavily damaged and a large outbuilding destroyed just north of the Boone/Webster county line. The tornado quickly moved northeast, crossing 390th Street and headed toward the Des Moines River, weakening to an F1 tornado. A continuous, but weak damage path was observed crossing the river as the tornado tracked across open farmland and land adjacent the Des Moines River. The tornado has been rated an F1 tornado during this time. After crossing County D64 in Webster county, the tornado struck another farm near 370th Street and Washington Avenue, damaging the residence and destroying a machine shed along with most of its contents. The tornado again intensified to an F2 at this location. The tornado then headed toward Stratford, crossing the Webster and Hamilton county line just west of County Road D54. The tornado entered Stratford at 4:46 p.m. on the west-central end of town, heavily damaging many homes. The tornado crossed the city park and then exited the city near the north-central portion of Stratford. Numerous homes were heavily damaged with one fatality. As the tornado left Stratford, it continued on a northeast track, lifting and dropping to the ground several times as an F0 and F1 tornado. It damaged three additional farms northeast of Stratford with the last damaged farm north of 320th Street and west of County Road R21 in Hamilton County. Tornado (2) touched down one mile west of Minburn in Dallas County according to the aerial survey. The tornado tracked northeast for about eight miles, producing F0-F1 damage before intensifying near Highway 141. The tornado produced F2 damage at a farm one mile southwest of Woodward, and continued to produce F2 damage through the south and east portions of Woodward. The tornado dissipated one mile northeast of Woodward. Severe houses slid off their foundations in Woodward, and a double-wide home was flipped upside down into the street. Total path length was 11 miles. Tornado (3) touched down in open fields one mile northwest of Madrid. It hit a home three miles north of Madrid on Highway 17, producing F1 damage. One other farm site sustained damage as the tornado moved northeast. The tornado dissipated after a six mile track. Tornado (4) started just west of Ames near the Highway 30 and Lincoln Way Split, according to the aerial survey. The tornado produced F1-F2 damage on the northwest fringe of Ames. It weakened as it moved northeast, before intensifying again and produced F2 damage to a farm site just south of Gilbert. F1 damage occurred as the tornado crossed highway 69. The tornado dissipated three miles south of Story City after a 10 mile track. Tornado (5) was a short-lived satellite tornado that was on the ground for 1.6 miles ending at the southwest edge of Story City. The aerial survey showed very minor damage. Tornado (6) developed one mile west of Roland and tracked across the extreme southeast corner of Hamilton county before entering Hardin county. The tornado produced damage up to F1 intensity to rural farm sites in far northern Story county and five miles south of Radcliffe in Hardin county. The KCCI-TV aerial survey indicated the track was nine miles in length. Tornado (7) was a brief touchdown just south of Williams in Hamilton County. No damage was found from this brief tornado and it is not shown here. Tornado (8) was briefly sighted near Blakesburg in Monroe County. The tornado produced minor damage to a farm building but was not surveyed. Tornado (9) touched down briefly north of Steamboat Rock in Hardin County. The tornado caused little damage. Tornado (10) was actually the first tornado of the day. It formed from the same supercell that eventually moved northeast into the Stratford area. The tornado caused little damage as it moved through fields south of the Scranton Area. Tornado (11) was a brief touchdown on the southwest edge of the Ames City limits. This tornado was from the same parent cell as the previous tornado that touched down in Ames, but was distinct. The tornado was weak and lifted lawn chairs and caused some shingle damage. This tornado was ANTICYCLONIC in nature. | |||||||||||
| 42.5 | 1962-05-07 | 2 | 42°04'N / 93°54'W | 42°07'N / 93°49'W | 4.90 Miles | 880 Yards | 0 | 0 | 250K | 0 | Boone |
| 43.1 | 1970-07-14 | 2 | 42°19'N / 93°26'W | 42°17'N / 93°23'W | 1.30 Miles | 250 Yards | 0 | 0 | 25K | 0 | Hardin |
| 43.3 | 1991-03-22 | 3 | 42°14'N / 93°22'W | 42°24'N / 93°09'W | 16.00 Miles | 70 Yards | 0 | 0 | 2.5M | 0 | Hardin |
| 43.8 | 2001-05-10 | 2 | 42°13'N / 92°45'W | 42°11'N / 92°42'W | 4.00 Miles | 750 Yards | 0 | 0 | 35K | 0 | Tama |
| Brief Description: Tornado moved out of Grundy County into Tama County. Track was through mostly rural areas with limited damage. A cold front frontal system located to the northwest of Iowa began to sink southeast into the state during the late afternoon of the 10th. This was in fact the same cold front that set off the thunderstorm activity the previous night. The atmosphere had become quite unstable by the late afternoon with temperatures in the 80s and dew point temperature in the low to mid 60s. CAPE values were in the 2000 to 3500 J/kg range. Thunderstorms erupted during the mid afternoon hours over the north central counties of the state. These storms produced hail of one to one and one half inches in diameter. The instability of the atmosphere, combined with a favorable sheer profile, contributed to the rather quick development of tornadic supercells. The first tornado touched down in Greene County. This tornado touched down briefly and did little damage. As the afternoon progressed, the hail became larger with several reports of hail up to golf ball size from central Iowa east into the east central counties. Some of the largest hail occurred southwest of State Center in Marshall County. Baseball size hail pelted the area, causing considerable damage. One supercell produced a family of at least four tornadoes in the Grundy County area. It is very fortunate that the tornadoes from this storm did not hit within a populated area. Two of the tornadoes were fairly large. At one point, the strongest tornado was about one half mile wide based on reports from a respectable storm chaser. This tornado tracked south through eastern Grundy County and crossed into Tama County. One barn was destroyed by the larger tornado, with a house damaged by the second strong tornado. Miraculously, though the first tornado totally destroyed the barn on a farm near Conrad, none of the animals inside were injured. In fact, it was reported that the livestock appeared to be enjoying their newfound freedom as they wandered the fields at the farm. There were reports of several small tornadoes touching down in central Iowa, however they were little more than brief touchdowns. As the event progressed into the early evening hours, the thunderstorms too on a more multi-cellular structure. The large cluster of storms lost their tornadic characteristic and returned to large hail producers. Hail from three quarter inch to one and three quarter inch was common for the next several hours as the entire area moved southeast slowly. By the mid evening hours the storms began to weaken. As they did, a few reports of winds of 60 to 70 MPH were received. In addition to the wind and hail, the storms produced locally heavy rainfall. Flash flooding was also a problem with this event. The cluster of storms that dropped the tornadoes in Grundy County during the late afternoon hours caused flash flooding in the south part of the county. Rainfall near Conrad was between 2.5 and 5 inches in under two hours time. This flooded roads with some of the state roads in the south part of the county under water. The water receded fairly quickly. A merger of cells took place over Monroe County during the mid evening hours. This resulted in very heavy rainfall in the area with reports of up to 4 inches received. Flash flooding resulted with numerous roads being closed by overflowing creeks by the mid to late evening hours. | |||||||||||
| 44.3 | 1976-06-13 | 3 | 41°43'N / 94°06'W | 41°51'N / 94°04'W | 8.80 Miles | 100 Yards | 0 | 0 | 250K | 0 | Dallas |
| 44.5 | 1964-05-07 | 2 | 42°06'N / 93°54'W | 0 | 0 | 25K | 0 | Boone | |||
| 44.5 | 1976-06-13 | 3 | 41°51'N / 94°04'W | 41°59'N / 94°01'W | 9.10 Miles | 33 Yards | 0 | 0 | 250K | 0 | Boone |
| 44.7 | 1989-05-24 | 4 | 42°11'N / 92°45'W | 42°12'N / 92°37'W | 8.00 Miles | 150 Yards | 0 | 0 | 25.0M | 0 | Tama |
| 44.7 | 1984-06-07 | 4 | 41°10'N / 92°40'W | 41°25'N / 92°26'W | 14.00 Miles | 250 Yards | 1 | 30 | 25.0M | 0 | Mahaska |
| 45.3 | 2001-05-10 | 2 | 42°17'N / 92°49'W | 42°14'N / 92°46'W | 4.00 Miles | 875 Yards | 0 | 0 | 35K | 0 | Grundy |
| Brief Description: Tornado dropped down north of Beaman and progressed southeast. Crossed into Tama County from Grundy County. Most of the track was through open country. A cold front frontal system located to the northwest of Iowa began to sink southeast into the state during the late afternoon of the 10th. This was in fact the same cold front that set off the thunderstorm activity the previous night. The atmosphere had become quite unstable by the late afternoon with temperatures in the 80s and dew point temperature in the low to mid 60s. CAPE values were in the 2000 to 3500 J/kg range. Thunderstorms erupted during the mid afternoon hours over the north central counties of the state. These storms produced hail of one to one and one half inches in diameter. The instability of the atmosphere, combined with a favorable sheer profile, contributed to the rather quick development of tornadic supercells. The first tornado touched down in Greene County. This tornado touched down briefly and did little damage. As the afternoon progressed, the hail became larger with several reports of hail up to golf ball size from central Iowa east into the east central counties. Some of the largest hail occurred southwest of State Center in Marshall County. Baseball size hail pelted the area, causing considerable damage. One supercell produced a family of at least four tornadoes in the Grundy County area. It is very fortunate that the tornadoes from this storm did not hit within a populated area. Two of the tornadoes were fairly large. At one point, the strongest tornado was about one half mile wide based on reports from a respectable storm chaser. This tornado tracked south through eastern Grundy County and crossed into Tama County. One barn was destroyed by the larger tornado, with a house damaged by the second strong tornado. Miraculously, though the first tornado totally destroyed the barn on a farm near Conrad, none of the animals inside were injured. In fact, it was reported that the livestock appeared to be enjoying their newfound freedom as they wandered the fields at the farm. There were reports of several small tornadoes touching down in central Iowa, however they were little more than brief touchdowns. As the event progressed into the early evening hours, the thunderstorms too on a more multi-cellular structure. The large cluster of storms lost their tornadic characteristic and returned to large hail producers. Hail from three quarter inch to one and three quarter inch was common for the next several hours as the entire area moved southeast slowly. By the mid evening hours the storms began to weaken. As they did, a few reports of winds of 60 to 70 MPH were received. In addition to the wind and hail, the storms produced locally heavy rainfall. Flash flooding was also a problem with this event. The cluster of storms that dropped the tornadoes in Grundy County during the late afternoon hours caused flash flooding in the south part of the county. Rainfall near Conrad was between 2.5 and 5 inches in under two hours time. This flooded roads with some of the state roads in the south part of the county under water. The water receded fairly quickly. A merger of cells took place over Monroe County during the mid evening hours. This resulted in very heavy rainfall in the area with reports of up to 4 inches received. Flash flooding resulted with numerous roads being closed by overflowing creeks by the mid to late evening hours. | |||||||||||
| 45.5 | 1967-06-09 | 2 | 41°02'N / 93°19'W | 2.00 Miles | 400 Yards | 0 | 0 | 25K | 0 | Lucas | |
| 46.5 | 1988-05-08 | 2 | 41°32'N / 92°24'W | 41°31'N / 92°19'W | 4.00 Miles | 60 Yards | 0 | 0 | 2.5M | 0 | Poweshiek |
| 47.2 | 1974-06-22 | 2 | 42°18'N / 93°39'W | 42°19'N / 93°36'W | 0 | 0 | 250K | 0 | Hamilton | ||
| 47.6 | 1979-03-29 | 3 | 41°10'N / 94°01'W | 41°16'N / 93°47'W | 13.60 Miles | 500 Yards | 0 | 1 | 0K | 0 | Madison |
| 48.0 | 1991-03-22 | 2 | 41°58'N / 94°06'W | 42°02'N / 94°02'W | 7.00 Miles | 50 Yards | 0 | 0 | 250K | 0 | Boone |
| 48.6 | 1967-06-09 | 2 | 41°03'N / 93°47'W | 41°08'N / 93°40'W | 7.80 Miles | 300 Yards | 0 | 0 | 250K | 0 | Clarke |
| 49.8 | 1990-03-13 | 2 | 42°02'N / 94°02'W | 42°18'N / 93°53'W | 16.00 Miles | 50 Yards | 0 | 0 | 2.5M | 0 | Boone |
* The information on this page is based on the global volcano database, the U.S. earthquake database of 1638-1985, and the U.S. Tornado and Weather Extremes database of 1950-2010.