Diagonal, IA Natural Disasters and Weather Extremes
Hot Rankings
The chance of earthquake damage in Diagonal is about the same as Iowa average and is much lower than the national average. The risk of tornado damage in Diagonal is higher than Iowa average and is much higher than the national average.
Earthquake Index, #363
| Diagonal, IA | 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
| Diagonal, IA | 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, #262
| Diagonal, IA | 258.47 |
| 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 3,203 other weather extremes events within 50 miles of Diagonal, IA 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: | 25 | Cold: | 39 | Dense Fog: | 8 | Drought: | 16 |
| Dust Storm: | 0 | Flood: | 330 | Hail: | 1,274 | Heat: | 19 | Heavy Snow: | 71 |
| High Surf: | 0 | Hurricane: | 0 | Ice Storm: | 39 | Landslide: | 0 | Strong Wind: | 56 |
| Thunderstorm Winds: | 1,036 | Tropical Storm: | 0 | Wildfire: | 0 | Winter Storm: | 84 | Winter Weather: | 69 |
| Other: | 137 | ||||||||
Volcanos Nearby
No volcano is found in or near Diagonal, IA.
Historical Earthquake Events
No historical earthquake events that had recorded magnitudes of 3.5 or above found in or near Diagonal, IA.
No historical earthquake events found in or near Diagonal, IA.
Historical Tornado Events
A total of 101 historical tornado events that had recorded magnitude of 2 or above found in or near Diagonal, IA.
| Distance (miles) | Date | Magnitude | Start Lat/Log | End Lat/Log | Length | Width | Fatalities | Injuries | Property Damage | Crop Damage | Affected County |
| 0.6 | 1971-05-05 | 2 | 40°49'N / 94°21'W | 1.00 Mile | 200 Yards | 0 | 0 | 25K | 0 | Ringgold | |
| 3.7 | 1955-04-23 | 3 | 40°43'N / 94°21'W | 40°48'N / 94°19'W | 5.40 Miles | 440 Yards | 0 | 0 | 25K | 0 | Ringgold |
| 6.5 | 2010-06-01 | 2 | 40°48'N / 94°13'W | 40°49'N / 94°13'W | 2.00 Miles | 250 Yards | 0 | 0 | 4.0M | 10K | Ringgold |
| Brief Description: EVENT NARRATIVE: A cone shape tornado was reported. Path was intermittent and the NWS survey suggests that the tornado hit a farmstead then lifted briefly skipping over some farms before setting back down and damaging another farmstead. Eyewittnesses also recount the tornado briefly lifting. EPISODE NARRATIVE: A cold front moved into Iowa from the northwest, while a warm front pushed into the southwest part of Iowa from the south during the afternoon and evening hours. Initially the airmass was very dry, however a strong push of moisture increased surface dew points into the upper 60s to low 70s by mid afternoon. Precipitable water values increased to 1.25 to 1.5 inches. The atmosphere destabilized by mid to late afternoon. Most unstable CAPE increased to 5000 J/kg as the lifted index fell to -9 to -12 C. The freezing level was relative low, around 12,000 feet. Available CAPE in the -10 to -30 C layer of the atmosphere increased to between 500 and 1000 J/kg. Downdraft CAPE was between 800 and 1000 J/kg. The atmosphere was moderately sheared with 40 to 55 kts of effective shear in the near storm environment. With the relatively dry air initially on the leading edge of the developing storms, the LCL was a relatively high 1500 meters. Thunderstorms formed in two areas. The first was over northwest Iowa along the cold frontal boundary. The second area developed over eastern Nebraska and tracked east in the warm advection area along and north of the warm frontal boundary. The two areas of storms combined during the evening hours, becoming a full fledged MCC by mid evening. All modes of severe weather occurred with this system, though the predominate mode was large hail. Thunderstorms formed rapidly along the warm frontal boundary during the mid and late afternoon. Hail up to baseball size was reported in southwest Iowa with these storms. Rapid intensification led to golf ball and larger hail in Taylor, Ringgold, Adams, and Union Counties. One of the storms produced a tornado as it moved through Ringgold County in the Tingley area. A large farmstead was hit, causing $4,000,000 damage. Eight buildings were damaged or destroyed, as well as the farmstead itself. Based upon extensive destruction to a 400 foot long metal cattle barn on the farmstead, it was determined that the tornado was of EF-2 strength with winds of up to 130 MPH. Other buildings, including the home, received extensive damage but not as widespread. Three head of cattle were killed when the cattle barn was destroyed. During the early evening the storm system transitioned into more of a high wind event. Several reports of 50 to 70 MPH winds were received. A wind gust in excess of 60 MPH threw house debris onto the street in Ottumwa. The storms produced heavy rainfall of 2 inches or more per hour. Fortunately they were moving relatively quickly. Storms trained over parts of Guthrie County. Over 4 inches of rain fell north and west of Guthrie Center. The heavy rainfall caused minor flooding with ditches filled and minor road flooding. A small area of flash flooding was reported along Seely Creek in Guthrie County with water a few feet over the road. Lightning caused at least two house fires. A house was struck east of Des Moines by one thunderstorm. The house was set on fire by the lightning. A second house was struck and set ablaze north of Ankeny. | |||||||||||
| 6.8 | 1989-05-24 | 4 | 40°53'N / 94°27'W | 40°41'N / 93°59'W | 26.00 Miles | 300 Yards | 0 | 0 | 25.0M | 0 | Ringgold |
| 8.3 | 1989-05-24 | 4 | 40°54'N / 94°28'W | 40°53'N / 94°27'W | 2.00 Miles | 300 Yards | 0 | 0 | 25.0M | 0 | Union |
| 9.0 | 1981-05-23 | 2 | 40°42'N / 94°19'W | 40°49'N / 94°03'W | 15.90 Miles | 130 Yards | 0 | 0 | 250K | 0 | Ringgold |
| 10.9 | 2001-04-11 | 3 | 40°34'N / 94°14'W | 40°53'N / 94°06'W | 23.50 Miles | 500 Yards | 0 | 0 | 1.5M | 0 | Ringgold |
| Brief Description: Tornado moved our of Missouri into Ringgold County, across the county into Union County. A very powerful storm system moved through the southern Rockies during the night of the 10th and early morning of the 11th. Intense surface low pressure formed over western Kansas with a central pressure by sunrise on the 11th of 977 Mb. The weather situation was very dynamic with 500 Mb winds over 100 kts and a very sharp dry punch clearly visible on the satellite pictures. During the day the warm front that extended east from the low reached into southern Iowa, then extended eastward. There were two things that occurred during the day. The first was a very strong supercell that formed over northern Missouri during the morning. This storm lifted north-northeast at about 50 kts into Iowa, producing a long track tornado with a path extending nearly all the way to Des Moines. During the afternoon the warm front surged north with the northeast progression of the surface dry line. Dew points rose into the mid 60s to the south of the warm front across much of the southeast half to two thirds of Iowa. Surface temperatures in these areas reached the 60s north, with 70s south. With the atmosphere primed, the dry line began to move into Iowa. Dew point temperatures behind the dry line were in the 30s with southwest winds of 30 to 50 MPH. A broken squall line formed on the nose of the dry punch and became severe quickly. The storm cells themselves were not all that large, but nearly every cell along the line did carry a mesoscale circulation. There were several tornado touchdowns as the line lifted north as well. The primary severe weather during this even was the tornadic nature of it. There were reports of wind and hail, but everything considered these reports were pretty scattered. There were very few reports of wind and hail with the first supercell as it lifted north out of Missouri. One inch diameter hail was reported in Ringgold County east of Redding. Reports of winds and hail were more frequent with the second line of thunderstorms. There were numerous reports of hail up to marble size with this line, however there were not all that many reports of hail larger than that. A few reports of three quarter to one inch diameter hail were received from Marion and Polk Counties. The most significant hail occurred in northeast Iowa in Butler County. Golf ball size hail fell in the town of Parkersburg as the line passed over the city. There were more reports of wind with the second round. Nearly all locations reported winds of at least 50 MPH as the line passed overhead. Scattered reports of winds of 70 to 85 MPH were received. Wind damage occurred in Boone County as high winds downed power lines and downed outbuildings north of Ogden. The greatest wind damage occurred over northeast Iowa in Black Hawk and Franklin Counties. A building was blown off of its foundation and onto an adjacent road southwest of Hampton in Franklin County. A roof of a barn was damaged and a grain wagon was tipped over northwest of Hampton. Roof and house damage was reported over parts of Black Hawk County as well. Five injuries occurred in Warren County at Carlisle when winds of around 65 MPH toppled a school bus. Twenty one children were on board the bus when it overturned with 5 treated for minor injuries. Spotty damage was reported around the greater Des Moines metropolitan area. Several tornadoes occurred with this system. The most significant tornado entered southern Iowa around mid day. This tornado reached minimal F3 intensity just east of Mt. Ayr (Ringgold County). Property damage is estimated at over $500,000 in Ringgold county alone. Across the Des Moines area of responsibility, at least 15 homes were destroyed, and 60 residences were damaged as around a dozen tornadoes touched down. A supercell thunderstorm moved north from Missouri into southern Iowa late in the morning of April 11. The storm produced a tornado in northern Missouri and crossed into Iowa in Ringgold County. The storm, and tornado, moved north through Ringgold County with a continuous damage path half way through the county. The damage path continued north through northern Ringgold County, southeast Union County and into northwest Clarke County. In this area, the path was not continuous. Based on damage reports, the tornado continued to produce occasional damage in Madison County. Chaser reports indicate the tornado had a multi-vortex structure as it moved through Ringgold and Union Counties. The last reported sighting was in northern Polk County where a brief touchdown was reported with no damage. The storm likely produced one tornado from the Missouri border to Madison County with an intermittent damage track. Damage in Ringgold County was severe with initial estimates around $1 million. The county was later declared a federal disaster area by President Bush. A second tornado briefly touched down in northern Polk County. The touchdown in Polk County was indeed a separate tornado. Even though the tornado was from the same parent cell, the system had occluded and was in the process of forming a new tornado as it passed over the western part of the Des Moines area. Reports from this tornado indicate that at least 9 homes were damaged or destroyed, one business destroyed, and a school building damaged. In addition to losses to homes, one farmstead was hit with considerable damage and some livestock damage. A series of tornadoes formed on the heels of the supercell tornado as the dry line pushed into the state. Most of these were brief touchdowns, however the storms were moving around 60 MPH. Three tornadoes touched down in Boone County. The most significant tornado touched down north of Ogden. It produced a 3 mile long track up to 1/8 mile wide. Farm site hit along highway P70. Barn and grain bins destroyed, knocking out windows in house. Otherwise only minor damage to house. Debris scattered 1 mile to next farm site where there was minor damage to many buildings. Track continued north-northeast across highway E26 into the campground at Don Williams Lake. A storage building was destroyed, several trees downed, plus outhouses, picnic tables and signs were damaged. The damage track dissipated on the northeast side of the Don Williams Recreation Area. There were several brief touchdowns with relatively minor damage in Guthrie, Greene, and Hamilton Counties. A stronger tornado touched down in southeast Black Hawk County, causing significant damage to two homes in the La Porte City area. The most serious tornado in terms of loss of life occurred in Wapello County. A tornado developed in rural southern Wapello County, a mile southwest of Agency, Iowa, around 1600 CDT, on Wednesday, April 11. The tornado path was 50 to 100 yards wide with sporadic touchdowns toward the north-northeast for the next 6 miles. Survey responses indicated that the duration of impact at any one location was only 15 to 30 seconds as the tornado quickly moved through Agency and over farms at a 60 mph horizontal movement. The Odd Fellows Lodge in Agency was destroyed, and over 50 residences were damaged. Two women inside were killed, three people injured and three people had no injuries. As the storm moved through Agency, a garage was lifted and carried about 100 meters off of its foundation. The car inside was twisted and covered with debris. In another incident, one house was hit by the tornado causing damage to the house. The family dog was in the dog pen at the time. The tornado lifted the pen and twirled it through the air. The dog pen was deposited some distance downstream and what was truly amazing was the fact that the dog was uninjured. Following the tornado, U.S. Highway 34 was closed for 2 hours in order to removed debris from the highway. Governor Tom Vilsack visited the area during a storm survey. The governor spoke with Brenda Brock of the National Weather Service, Ellen Gordon, Administrator, Iowa Emergency Management Division, emergency management personnel (fire department, law enforcement, mayor) and the public. A proclamation for emergency disaster assistance was signed. | |||||||||||
| 11.2 | 1964-04-12 | 2 | 40°55'N / 94°28'W | 41°01'N / 94°20'W | 9.40 Miles | 33 Yards | 0 | 0 | 250K | 0 | Union |
| 12.7 | 1990-07-25 | 2 | 40°49'N / 94°08'W | 40°51'N / 94°04'W | 4.00 Miles | 73 Yards | 0 | 0 | 250K | 0 | Ringgold |
| 12.8 | 1966-10-14 | 2 | 40°47'N / 94°35'W | 1.50 Miles | 100 Yards | 0 | 0 | 25K | 0 | Taylor | |
| 12.8 | 1958-07-14 | 3 | 40°54'N / 94°35'W | 40°50'N / 94°34'W | 3.60 Miles | 100 Yards | 0 | 0 | 250K | 0 | Taylor |
| 13.0 | 1984-06-07 | 2 | 40°41'N / 94°14'W | 40°44'N / 94°02'W | 14.00 Miles | 150 Yards | 1 | 3 | 2.5M | 0 | Ringgold |
| 13.1 | 1979-03-29 | 3 | 40°46'N / 94°23'W | 41°10'N / 94°01'W | 33.50 Miles | 500 Yards | 0 | 2 | 2.5M | 0 | Union |
| 14.1 | 1964-04-26 | 2 | 40°54'N / 94°16'W | 40°59'N / 94°00'W | 14.80 Miles | 300 Yards | 0 | 0 | 25K | 0 | Union |
| 15.3 | 1966-10-14 | 2 | 40°50'N / 94°38'W | 0 | 0 | 0K | 0 | Taylor | |||
| 15.8 | 1971-05-05 | 3 | 40°45'N / 94°38'W | 2.00 Miles | 400 Yards | 0 | 12 | 250K | 0 | Taylor | |
| 15.9 | 1989-05-24 | 4 | 40°59'N / 94°43'W | 40°54'N / 94°28'W | 12.00 Miles | 1760 Yards | 0 | 0 | 25.0M | 0 | Adams |
| 17.7 | 1958-07-14 | 3 | 41°04'N / 94°36'W | 40°54'N / 94°35'W | 11.20 Miles | 100 Yards | 0 | 1 | 250K | 0 | Adams |
| 19.7 | 2001-04-11 | 2 | 40°56'N / 94°04'W | 41°03'N / 94°02'W | 11.50 Miles | 150 Yards | 0 | 0 | 150K | 0 | Union |
| Brief Description: Tornado moved from Ringgold County, across Union County, into Clarke County. A very powerful storm system moved through the southern Rockies during the night of the 10th and early morning of the 11th. Intense surface low pressure formed over western Kansas with a central pressure by sunrise on the 11th of 977 Mb. The weather situation was very dynamic with 500 Mb winds over 100 kts and a very sharp dry punch clearly visible on the satellite pictures. During the day the warm front that extended east from the low reached into southern Iowa, then extended eastward. There were two things that occurred during the day. The first was a very strong supercell that formed over northern Missouri during the morning. This storm lifted north-northeast at about 50 kts into Iowa, producing a long track tornado with a path extending nearly all the way to Des Moines. During the afternoon the warm front surged north with the northeast progression of the surface dry line. Dew points rose into the mid 60s to the south of the warm front across much of the southeast half to two thirds of Iowa. Surface temperatures in these areas reached the 60s north, with 70s south. With the atmosphere primed, the dry line began to move into Iowa. Dew point temperatures behind the dry line were in the 30s with southwest winds of 30 to 50 MPH. A broken squall line formed on the nose of the dry punch and became severe quickly. The storm cells themselves were not all that large, but nearly every cell along the line did carry a mesoscale circulation. There were several tornado touchdowns as the line lifted north as well. The primary severe weather during this even was the tornadic nature of it. There were reports of wind and hail, but everything considered these reports were pretty scattered. There were very few reports of wind and hail with the first supercell as it lifted north out of Missouri. One inch diameter hail was reported in Ringgold County east of Redding. Reports of winds and hail were more frequent with the second line of thunderstorms. There were numerous reports of hail up to marble size with this line, however there were not all that many reports of hail larger than that. A few reports of three quarter to one inch diameter hail were received from Marion and Polk Counties. The most significant hail occurred in northeast Iowa in Butler County. Golf ball size hail fell in the town of Parkersburg as the line passed over the city. There were more reports of wind with the second round. Nearly all locations reported winds of at least 50 MPH as the line passed overhead. Scattered reports of winds of 70 to 85 MPH were received. Wind damage occurred in Boone County as high winds downed power lines and downed outbuildings north of Ogden. The greatest wind damage occurred over northeast Iowa in Black Hawk and Franklin Counties. A building was blown off of its foundation and onto an adjacent road southwest of Hampton in Franklin County. A roof of a barn was damaged and a grain wagon was tipped over northwest of Hampton. Roof and house damage was reported over parts of Black Hawk County as well. Five injuries occurred in Warren County at Carlisle when winds of around 65 MPH toppled a school bus. Twenty one children were on board the bus when it overturned with 5 treated for minor injuries. Spotty damage was reported around the greater Des Moines metropolitan area. Several tornadoes occurred with this system. The most significant tornado entered southern Iowa around mid day. This tornado reached minimal F3 intensity just east of Mt. Ayr (Ringgold County). Property damage is estimated at over $500,000 in Ringgold county alone. Across the Des Moines area of responsibility, at least 15 homes were destroyed, and 60 residences were damaged as around a dozen tornadoes touched down. A supercell thunderstorm moved north from Missouri into southern Iowa late in the morning of April 11. The storm produced a tornado in northern Missouri and crossed into Iowa in Ringgold County. The storm, and tornado, moved north through Ringgold County with a continuous damage path half way through the county. The damage path continued north through northern Ringgold County, southeast Union County and into northwest Clarke County. In this area, the path was not continuous. Based on damage reports, the tornado continued to produce occasional damage in Madison County. Chaser reports indicate the tornado had a multi-vortex structure as it moved through Ringgold and Union Counties. The last reported sighting was in northern Polk County where a brief touchdown was reported with no damage. The storm likely produced one tornado from the Missouri border to Madison County with an intermittent damage track. Damage in Ringgold County was severe with initial estimates around $1 million. The county was later declared a federal disaster area by President Bush. A second tornado briefly touched down in northern Polk County. The touchdown in Polk County was indeed a separate tornado. Even though the tornado was from the same parent cell, the system had occluded and was in the process of forming a new tornado as it passed over the western part of the Des Moines area. Reports from this tornado indicate that at least 9 homes were damaged or destroyed, one business destroyed, and a school building damaged. In addition to losses to homes, one farmstead was hit with considerable damage and some livestock damage. A series of tornadoes formed on the heels of the supercell tornado as the dry line pushed into the state. Most of these were brief touchdowns, however the storms were moving around 60 MPH. Three tornadoes touched down in Boone County. The most significant tornado touched down north of Ogden. It produced a 3 mile long track up to 1/8 mile wide. Farm site hit along highway P70. Barn and grain bins destroyed, knocking out windows in house. Otherwise only minor damage to house. Debris scattered 1 mile to next farm site where there was minor damage to many buildings. Track continued north-northeast across highway E26 into the campground at Don Williams Lake. A storage building was destroyed, several trees downed, plus outhouses, picnic tables and signs were damaged. The damage track dissipated on the northeast side of the Don Williams Recreation Area. There were several brief touchdowns with relatively minor damage in Guthrie, Greene, and Hamilton Counties. A stronger tornado touched down in southeast Black Hawk County, causing significant damage to two homes in the La Porte City area. The most serious tornado in terms of loss of life occurred in Wapello County. A tornado developed in rural southern Wapello County, a mile southwest of Agency, Iowa, around 1600 CDT, on Wednesday, April 11. The tornado path was 50 to 100 yards wide with sporadic touchdowns toward the north-northeast for the next 6 miles. Survey responses indicated that the duration of impact at any one location was only 15 to 30 seconds as the tornado quickly moved through Agency and over farms at a 60 mph horizontal movement. The Odd Fellows Lodge in Agency was destroyed, and over 50 residences were damaged. Two women inside were killed, three people injured and three people had no injuries. As the storm moved through Agency, a garage was lifted and carried about 100 meters off of its foundation. The car inside was twisted and covered with debris. In another incident, one house was hit by the tornado causing damage to the house. The family dog was in the dog pen at the time. The tornado lifted the pen and twirled it through the air. The dog pen was deposited some distance downstream and what was truly amazing was the fact that the dog was uninjured. Following the tornado, U.S. Highway 34 was closed for 2 hours in order to removed debris from the highway. Governor Tom Vilsack visited the area during a storm survey. The governor spoke with Brenda Brock of the National Weather Service, Ellen Gordon, Administrator, Iowa Emergency Management Division, emergency management personnel (fire department, law enforcement, mayor) and the public. A proclamation for emergency disaster assistance was signed. | |||||||||||
| 19.9 | 1999-04-08 | 4 | 41°02'N / 94°19'W | 41°09'N / 94°12'W | 12.50 Miles | 1500 Yards | 0 | 1 | 2.0M | 0 | Union |
| 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. | |||||||||||
| 21.1 | 1955-04-23 | 2 | 40°31'N / 94°32'W | 40°33'N / 94°29'W | 3.00 Miles | 100 Yards | 0 | 1 | 25K | 0 | Worth |
| 21.5 | 2001-04-11 | 2 | 40°24'N / 94°22'W | 40°36'N / 94°18'W | 14.00 Miles | 100 Yards | 0 | 0 | 100K | 0 | Worth |
| Brief Description: The tornado that initially touched down in Gentry county, crossed into Worth county at 1032 am, 2 miles west of Denver. It crossed into Iowa 8 miles north of Allendale at 1040 am. One home was destroyed along with several out buildings. | |||||||||||
| 22.3 | 1979-03-29 | 3 | 40°35'N / 94°57'W | 40°54'N / 94°34'W | 29.60 Miles | 500 Yards | 0 | 1 | 2.5M | 0 | Taylor |
| 23.6 | 1959-05-18 | 2 | 40°59'N / 94°44'W | 1.00 Mile | 200 Yards | 0 | 0 | 250K | 0 | Adams | |
| 24.1 | 1954-04-05 | 2 | 40°40'N / 94°53'W | 40°43'N / 94°40'W | 11.50 Miles | 333 Yards | 0 | 0 | 0K | 0 | Taylor |
| 24.2 | 1989-05-24 | 4 | 40°41'N / 93°59'W | 40°38'N / 93°52'W | 9.00 Miles | 300 Yards | 0 | 0 | 25.0M | 0 | Decatur |
| 24.6 | 1984-06-07 | 3 | 40°53'N / 94°50'W | 40°59'N / 94°44'W | 11.00 Miles | 100 Yards | 0 | 0 | 2.5M | 0 | Adams |
| 26.0 | 1981-04-11 | 2 | 40°41'N / 94°45'W | 40°43'N / 94°53'W | 6.90 Miles | 50 Yards | 0 | 2 | 2.5M | 0 | Taylor |
| 26.0 | 1972-06-13 | 2 | 41°07'N / 94°03'W | 2.00 Miles | 100 Yards | 0 | 0 | 25K | 0 | Union | |
| 26.3 | 1958-10-08 | 3 | 40°27'N / 94°13'W | 40°27'N / 94°09'W | 3.00 Miles | 300 Yards | 0 | 0 | 250K | 0 | Harrison |
| 26.3 | 1958-10-10 | 3 | 40°25'N / 94°36'W | 40°27'N / 94°13'W | 20.10 Miles | 300 Yards | 2 | 7 | 250K | 0 | Worth |
| 26.6 | 1975-05-07 | 2 | 40°49'N / 93°50'W | 0 | 0 | 25K | 0 | Decatur | |||
| 27.0 | 1964-06-22 | 2 | 40°56'N / 93°59'W | 41°03'N / 93°47'W | 12.80 Miles | 400 Yards | 0 | 0 | 250K | 0 | Clarke |
| 28.6 | 1959-05-04 | 2 | 41°12'N / 94°24'W | 41°15'N / 94°19'W | 4.50 Miles | 100 Yards | 0 | 0 | 3K | 0 | Adair |
| 28.9 | 1984-06-07 | 3 | 40°50'N / 94°57'W | 40°53'N / 94°50'W | 7.00 Miles | 100 Yards | 0 | 0 | 2.5M | 0 | Taylor |
| 29.2 | 1971-05-05 | 2 | 40°47'N / 94°54'W | 0 | 1 | 25K | 0 | Taylor | |||
| 29.5 | 1999-04-08 | 2 | 40°51'N / 94°54'W | 40°54'N / 94°54'W | 3.00 Miles | 500 Yards | 0 | 0 | 500K | 0 | Taylor |
| 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. | |||||||||||
| 29.5 | 2001-04-11 | 2 | 41°04'N / 94°01'W | 41°11'N / 93°54'W | 10.00 Miles | 150 Yards | 0 | 0 | 125K | 0 | Clarke |
| Brief Description: Tornado moved from Union County into Clarke County, then moved into Madison County. A very powerful storm system moved through the southern Rockies during the night of the 10th and early morning of the 11th. Intense surface low pressure formed over western Kansas with a central pressure by sunrise on the 11th of 977 Mb. The weather situation was very dynamic with 500 Mb winds over 100 kts and a very sharp dry punch clearly visible on the satellite pictures. During the day the warm front that extended east from the low reached into southern Iowa, then extended eastward. There were two things that occurred during the day. The first was a very strong supercell that formed over northern Missouri during the morning. This storm lifted north-northeast at about 50 kts into Iowa, producing a long track tornado with a path extending nearly all the way to Des Moines. During the afternoon the warm front surged north with the northeast progression of the surface dry line. Dew points rose into the mid 60s to the south of the warm front across much of the southeast half to two thirds of Iowa. Surface temperatures in these areas reached the 60s north, with 70s south. With the atmosphere primed, the dry line began to move into Iowa. Dew point temperatures behind the dry line were in the 30s with southwest winds of 30 to 50 MPH. A broken squall line formed on the nose of the dry punch and became severe quickly. The storm cells themselves were not all that large, but nearly every cell along the line did carry a mesoscale circulation. There were several tornado touchdowns as the line lifted north as well. The primary severe weather during this even was the tornadic nature of it. There were reports of wind and hail, but everything considered these reports were pretty scattered. There were very few reports of wind and hail with the first supercell as it lifted north out of Missouri. One inch diameter hail was reported in Ringgold County east of Redding. Reports of winds and hail were more frequent with the second line of thunderstorms. There were numerous reports of hail up to marble size with this line, however there were not all that many reports of hail larger than that. A few reports of three quarter to one inch diameter hail were received from Marion and Polk Counties. The most significant hail occurred in northeast Iowa in Butler County. Golf ball size hail fell in the town of Parkersburg as the line passed over the city. There were more reports of wind with the second round. Nearly all locations reported winds of at least 50 MPH as the line passed overhead. Scattered reports of winds of 70 to 85 MPH were received. Wind damage occurred in Boone County as high winds downed power lines and downed outbuildings north of Ogden. The greatest wind damage occurred over northeast Iowa in Black Hawk and Franklin Counties. A building was blown off of its foundation and onto an adjacent road southwest of Hampton in Franklin County. A roof of a barn was damaged and a grain wagon was tipped over northwest of Hampton. Roof and house damage was reported over parts of Black Hawk County as well. Five injuries occurred in Warren County at Carlisle when winds of around 65 MPH toppled a school bus. Twenty one children were on board the bus when it overturned with 5 treated for minor injuries. Spotty damage was reported around the greater Des Moines metropolitan area. Several tornadoes occurred with this system. The most significant tornado entered southern Iowa around mid day. This tornado reached minimal F3 intensity just east of Mt. Ayr (Ringgold County). Property damage is estimated at over $500,000 in Ringgold county alone. Across the Des Moines area of responsibility, at least 15 homes were destroyed, and 60 residences were damaged as around a dozen tornadoes touched down. A supercell thunderstorm moved north from Missouri into southern Iowa late in the morning of April 11. The storm produced a tornado in northern Missouri and crossed into Iowa in Ringgold County. The storm, and tornado, moved north through Ringgold County with a continuous damage path half way through the county. The damage path continued north through northern Ringgold County, southeast Union County and into northwest Clarke County. In this area, the path was not continuous. Based on damage reports, the tornado continued to produce occasional damage in Madison County. Chaser reports indicate the tornado had a multi-vortex structure as it moved through Ringgold and Union Counties. The last reported sighting was in northern Polk County where a brief touchdown was reported with no damage. The storm likely produced one tornado from the Missouri border to Madison County with an intermittent damage track. Damage in Ringgold County was severe with initial estimates around $1 million. The county was later declared a federal disaster area by President Bush. A second tornado briefly touched down in northern Polk County. The touchdown in Polk County was indeed a separate tornado. Even though the tornado was from the same parent cell, the system had occluded and was in the process of forming a new tornado as it passed over the western part of the Des Moines area. Reports from this tornado indicate that at least 9 homes were damaged or destroyed, one business destroyed, and a school building damaged. In addition to losses to homes, one farmstead was hit with considerable damage and some livestock damage. A series of tornadoes formed on the heels of the supercell tornado as the dry line pushed into the state. Most of these were brief touchdowns, however the storms were moving around 60 MPH. Three tornadoes touched down in Boone County. The most significant tornado touched down north of Ogden. It produced a 3 mile long track up to 1/8 mile wide. Farm site hit along highway P70. Barn and grain bins destroyed, knocking out windows in house. Otherwise only minor damage to house. Debris scattered 1 mile to next farm site where there was minor damage to many buildings. Track continued north-northeast across highway E26 into the campground at Don Williams Lake. A storage building was destroyed, several trees downed, plus outhouses, picnic tables and signs were damaged. The damage track dissipated on the northeast side of the Don Williams Recreation Area. There were several brief touchdowns with relatively minor damage in Guthrie, Greene, and Hamilton Counties. A stronger tornado touched down in southeast Black Hawk County, causing significant damage to two homes in the La Porte City area. The most serious tornado in terms of loss of life occurred in Wapello County. A tornado developed in rural southern Wapello County, a mile southwest of Agency, Iowa, around 1600 CDT, on Wednesday, April 11. The tornado path was 50 to 100 yards wide with sporadic touchdowns toward the north-northeast for the next 6 miles. Survey responses indicated that the duration of impact at any one location was only 15 to 30 seconds as the tornado quickly moved through Agency and over farms at a 60 mph horizontal movement. The Odd Fellows Lodge in Agency was destroyed, and over 50 residences were damaged. Two women inside were killed, three people injured and three people had no injuries. As the storm moved through Agency, a garage was lifted and carried about 100 meters off of its foundation. The car inside was twisted and covered with debris. In another incident, one house was hit by the tornado causing damage to the house. The family dog was in the dog pen at the time. The tornado lifted the pen and twirled it through the air. The dog pen was deposited some distance downstream and what was truly amazing was the fact that the dog was uninjured. Following the tornado, U.S. Highway 34 was closed for 2 hours in order to removed debris from the highway. Governor Tom Vilsack visited the area during a storm survey. The governor spoke with Brenda Brock of the National Weather Service, Ellen Gordon, Administrator, Iowa Emergency Management Division, emergency management personnel (fire department, law enforcement, mayor) and the public. A proclamation for emergency disaster assistance was signed. | |||||||||||
| 29.5 | 1984-06-07 | 4 | 40°25'N / 94°02'W | 40°34'N / 93°54'W | 10.00 Miles | 200 Yards | 1 | 1 | 2.5M | 0 | Harrison |
| 29.7 | 1999-04-08 | 4 | 40°53'N / 94°53'W | 41°09'N / 94°48'W | 18.00 Miles | 1000 Yards | 0 | 1 | 1.0M | 0 | Adams |
| 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. | |||||||||||
| 30.8 | 1958-10-08 | 3 | 40°25'N / 94°38'W | 40°25'N / 94°36'W | 0 | 0 | 250K | 0 | Nodaway | ||
| 30.9 | 1986-07-13 | 2 | 41°01'N / 93°49'W | 1.00 Mile | 50 Yards | 0 | 0 | 250K | 0 | Clarke | |
| 31.4 | 1964-06-22 | 2 | 40°44'N / 93°45'W | 1.00 Mile | 200 Yards | 0 | 0 | 250K | 0 | Decatur | |
| 32.1 | 1960-04-16 | 3 | 40°22'N / 94°13'W | 40°25'N / 93°56'W | 15.10 Miles | 300 Yards | 0 | 4 | 25K | 0 | Harrison |
| 32.7 | 1964-06-19 | 3 | 40°44'N / 95°03'W | 40°50'N / 94°53'W | 10.60 Miles | 200 Yards | 0 | 1 | 250K | 0 | Page |
| 32.9 | 1975-05-07 | 2 | 41°02'N / 93°47'W | 10.00 Miles | 33 Yards | 0 | 0 | 250K | 0 | Clarke | |
| 33.0 | 1960-04-16 | 3 | 40°18'N / 94°26'W | 40°22'N / 94°13'W | 11.90 Miles | 300 Yards | 0 | 0 | 25K | 0 | Benton |
| 33.2 | 1973-04-19 | 2 | 41°06'N / 93°50'W | 2.00 Miles | 400 Yards | 0 | 0 | 25K | 0 | Clarke | |
| 33.6 | 1980-06-02 | 4 | 40°37'N / 93°55'W | 40°36'N / 93°36'W | 16.50 Miles | 140 Yards | 0 | 0 | 2.5M | 0 | Decatur |
| 34.0 | 1999-04-08 | 3 | 41°09'N / 94°47'W | 41°15'N / 94°42'W | 7.50 Miles | 1000 Yards | 0 | 0 | 186K | 0 | Cass |
| 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. | |||||||||||
| 34.0 | 1984-06-07 | 3 | 40°44'N / 95°02'W | 40°50'N / 94°57'W | 7.00 Miles | 100 Yards | 0 | 3 | 2.5M | 0 | Page |
| 34.4 | 1984-06-07 | 4 | 40°35'N / 93°54'W | 40°44'N / 93°32'W | 22.00 Miles | 250 Yards | 0 | 0 | 25.0M | 0 | Decatur |
| 34.9 | 1952-11-16 | 3 | 40°27'N / 95°04'W | 40°34'N / 94°41'W | 21.60 Miles | 600 Yards | 0 | 2 | 25K | 0 | Nodaway |
| 34.9 | 1959-05-04 | 2 | 41°17'N / 94°30'W | 41°20'N / 94°25'W | 5.10 Miles | 100 Yards | 0 | 0 | 3K | 0 | Adair |
| 35.3 | 1979-03-29 | 4 | 40°34'N / 95°02'W | 40°42'N / 94°55'W | 10.80 Miles | 500 Yards | 0 | 16 | 2.5M | 0 | Page |
| 35.5 | 1963-04-18 | 2 | 41°10'N / 94°50'W | 0 | 0 | 25K | 0 | Cass | |||
| 36.2 | 1965-09-20 | 2 | 41°03'N / 93°46'W | 41°03'N / 93°41'W | 3.30 Miles | 150 Yards | 0 | 0 | 250K | 0 | Clarke |
| 36.3 | 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 |
| 37.1 | 1994-04-14 | 3 | 41°16'N / 94°42'W | 41°22'N / 94°28'W | 14.00 Miles | 130 Yards | 0 | 0 | 500K | 0 | Adair |
| Brief Description: Mostly F1 and F2 Damage. | |||||||||||
| 37.2 | 1961-04-23 | 2 | 40°43'N / 93°44'W | 40°43'N / 93°33'W | 9.30 Miles | 600 Yards | 0 | 2 | 2.5M | 0 | Decatur |
| 37.5 | 1964-04-12 | 2 | 40°54'N / 95°03'W | 2.00 Miles | 150 Yards | 0 | 0 | 25K | 0 | Montgomery | |
| 37.6 | 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 |
| 37.7 | 1970-04-29 | 2 | 40°25'N / 93°59'W | 40°35'N / 93°31'W | 27.00 Miles | 440 Yards | 0 | 0 | 250K | 0 | Harrison |
| 37.9 | 1959-05-10 | 2 | 40°56'N / 95°03'W | 1.00 Mile | 200 Yards | 0 | 0 | 3K | 0 | Montgomery | |
| 38.3 | 1999-04-08 | 2 | 41°11'N / 94°14'W | 41°30'N / 94°01'W | 24.50 Miles | 1250 Yards | 0 | 0 | 350K | 0 | Madison |
| 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. | |||||||||||
| 39.4 | 1969-06-29 | 2 | 40°15'N / 94°37'W | 40°17'N / 94°31'W | 5.10 Miles | 100 Yards | 0 | 0 | 250K | 0 | Nodaway |
| 39.7 | 1963-04-18 | 2 | 41°20'N / 94°38'W | 41°22'N / 94°35'W | 1.90 Miles | 200 Yards | 0 | 0 | 25K | 0 | Adair |
| 39.9 | 1989-05-24 | 2 | 40°26'N / 93°46'W | 2.50 Miles | 73 Yards | 0 | 0 | 2.5M | 0 | Harrison | |
| 40.5 | 1999-04-08 | 4 | 41°15'N / 94°43'W | 41°29'N / 94°28'W | 20.50 Miles | 1500 Yards | 0 | 2 | 1.0M | 0 | Adair |
| 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. | |||||||||||
| 40.6 | 2004-05-24 | 2 | 40°12'N / 94°33'W | 40°15'N / 94°15'W | 17.00 Miles | 250 Yards | 0 | 1 | 10.0M | 0 | Gentry |
| Brief Description: This F2 tornado was consistently on the ground from one mile south of Stanberry east-northeast through Albany. Muliple vortices were noticed on chaser video. Extensive damage was observed in Albany. Three homes were destroyed. There were 34 buildings with major damage and 70 buildings had minor damage. | |||||||||||
| 41.5 | 1974-05-13 | 3 | 41°08'N / 95°04'W | 41°13'N / 94°53'W | 10.90 Miles | 20 Yards | 0 | 0 | 250K | 0 | Montgomery |
| 41.6 | 1984-04-26 | 2 | 40°12'N / 94°33'W | 40°14'N / 94°24'W | 7.00 Miles | 100 Yards | 0 | 0 | 250K | 0 | Gentry |
| 41.9 | 2004-08-26 | 2 | 40°40'N / 95°12'W | 40°39'N / 95°02'W | 7.00 Miles | 1200 Yards | 0 | 0 | 0 | 0 | Page |
| Brief Description: This tornado first touched down around 2 miles east of Coin and tracked 7 miles before lifting just northwest of Shambaugh. The tornado reached it's maximum intensity of f2 north of College Springs where a farmstead sustained serious damage. The roof of a house at this farmstead was removed and siding was damaged, a hay barn was flattened, grain bins were crushed and the roof of a silo and other nearby outbuildings were destroyed. Other farmsteads received damage to outbuildings and the crop and tree damage path at times widened to 3/4 of a mile. | |||||||||||
| 41.9 | 2007-05-06 | 2 | 41°10'N / 94°58'W | 41°15'N / 94°56'W | 7.00 Miles | 830 Yards | 0 | 0 | 1.0M | 0K | Cass |
| Brief Description: EVENT NARRATIVE: Tornado touched down on the southern Cass County line and moved northeast. The last 2 miles of the track showed an intermittent nature. Average path width was 100 to 200 yards wide with a maximum width of about one half mile. Estimated wind speed was 120 to 130 MPH. EPISODE NARRATIVE: A very strong upper level low pressure trough had carved out over the western U.S. Iowa was in the strong southwest flow on the front side of this system. A surface warm front lifted north into southwest Iowa during the evening of the 5th. The airmass became quite unstable with plenty of deep moisture advection into the areas. Precipitable water values were in the 1.5 to 1.75 inch range by midnight. The lifted index fell to the -6 to -8 C. There was a reasonable amount of CAPE available with about 2500 J/kg at the onset of the event. The LCL was around 1000 meters and the freezing level was a relatively high 13,500 feet. With the warm front in the vicinity, there was a considerable amount of helicity present with values in the 300 to 550 range. During the evening of the 5th, most of the significant convection remained to the west of the DMX CWA. After midnight, the low level jet increased to 50 to 70 kts and began to veer. This helped push the convection east during the overnight hours. Strong cells developed in southwest Iowa near the warm frontal boundary. Two tornadoes occurred with this initial set of convection. An EF2 tornado touched down in Cass County. The tornado first developed right on the southern Cass County line, from highway 71 to three quarters of a mile west. Four farmsteads were damaged along county road G66 within the mile west of highway 71, producing damage up to EF1. The tornado narrowed slightly and intensified in the next mile, downing two sets of metal electrical transmission poles. The most severe damage occurred at a farm service and grain elevator business on highway 71. This was 2 miles into Cass County or 3 miles south of the town of Lyman. EF2 damage occurred at this site with winds estimated at 120-130 mph. The average path width was 100 to 200 yards, with a maximum width of about one half mile. Empty semi trailers were flipped, two tall grain bins were flattened. A large metal clad truck service building was flattened on the south end and much of the roof was off the north end. The west part of the roof of an office building was torn off and the wall collapsed. The house at the north end of the site had windows blown out and part of the roof damaged. The tornado continued north along and just east of highway 71 for another two miles causing some damage to homes with some outbuildings unroofed or destroyed. The last apparent damage along the tornado path occurred two miles northeast of Lyman where power poles were snapped. Several areas between Cumberland and Anita were also surveyed. Damage along this path was consistent with straight line winds of 70 to 90 mph. Damage included downed trees and sheet metal torn off sheds and outbuildings. A storage building in Anita was significantly damaged. A total of 115 to 120 homes were damaged in Cass County by the storm. As the night progressed, a bow echo advanced into the state from the southwest. There were several reports of high winds and hail with this line. One of the storm in the line produced a small EF0 tornado in Union County. Some damage occurred at several farmsteads along the path. This same cell produced very large hail with hail up to baseball size reported in the Afton area. The hail was wind driven, damaging skylights, windows, and cars. Hail stones were driven through car windshields and also through windows in houses. Some damage even occurred inside of two homes as the hail stones continued inside of the house. This was the most significant hail from the storms. The hail reportedly piled up several inches deep and lasted for at least 4 hours after the storm. In the survey conducted by the Emergency Manager it was found that in Afton, 236 primary buildings and 174 out buildings and garages had moderate hail damage consisting of roof damage...primarily to the slopes facing south and west. All roof vents and eves, either aluminum or plastic, were damaged. Almost 100 percent of the buildings with south-facing windows had damage to screens, broken glass storm windows, interior single and double pane windows, and in cases of plastic framed windows even the sashes and stools were damaged. All siding was damaged on those sides no matter of the material. In the rural areas around Afton, 30 of the 38 residences received moderate damage. In Arispe, 5 miles south of Afton, hail damage occurred, but was not as severe with 40 residences reporting minor damage and 30 out buildings being damaged. All together, 346 vehicles were hail damaged and many had Windows broken completely out. Twenty three campers suffered vent and sky lite damages as well as exterior damages. Hardly any of the skylights withstood the hail, either in campers or houses. Though many of the storms produced hail, much of it was under one half inch in diameter. Another brief tornado touched town in Guthrie County south of Bayard. The tornado caused EF1 damage. A roof was blown off of a building there, and blown westward. Wind was the primary threat with the storms. There were several reports of trees downed by the high winds, barns, and outbuildings being blown over or destroyed. A semi-tractortrailer was blown off of Interstate 80 west of Adair. The event turned into a significant event both in areal coverage, as well as for its variety of weather features. Flooding became a significant problem later in the event with several reports of 3 to 5 inch rainfall received. Flash flooding occurred over parts of southwest into west central Iowa. Cass, Audubon, and Carroll Counties were the hardest hit. Areal flood warnings were issued for these counties. Widespread flooding too place, with Cass County hard hit. The Governor of Iowa, Chet Culver, declared a state disaster for several counties across southwest and south central Iowa due to the flash flooding. This included Decatur County in the Des Moines CWA. Toward dawn, high winds became a problem over parts of northwest Iowa. The winds affected a 6 county area with wind gusts in the 50 to 65 MPH range for several hours. | |||||||||||
| 41.9 | 1995-05-27 | 4 | 41°04'N / 94°25'W | 41°46'N / 94°09'W | 55.00 Miles | 500 Yards | 0 | 2 | 3.0M | 80K | Union, Adair, Guthrie And Dallas |
| Brief Description: Twin vortex tornado. | |||||||||||
| 43.3 | 1964-04-12 | 4 | 40°40'N / 95°14'W | 40°50'N / 95°06'W | 13.10 Miles | 400 Yards | 1 | 28 | 2.5M | 0 | Page |
| 44.0 | 1979-03-29 | 4 | 40°29'N / 95°09'W | 40°34'N / 95°02'W | 8.00 Miles | 500 Yards | 0 | 4 | 0K | 0 | Nodaway |
| 44.0 | 1964-09-22 | 2 | 40°39'N / 95°14'W | 40°48'N / 95°07'W | 11.80 Miles | 300 Yards | 0 | 0 | 250K | 0 | Page |
| 44.1 | 1964-04-12 | 2 | 40°17'N / 94°59'W | 40°23'N / 94°49'W | 10.80 Miles | 80 Yards | 0 | 0 | 2.5M | 0 | Nodaway |
| 44.6 | 2004-05-29 | 4 | 40°12'N / 94°02'W | 40°13'N / 94°02'W | 2.00 Miles | 800 Yards | 0 | 0 | 0 | 0 | Harrison |
| Brief Description: Large F4 tornado crossed into Harrison county from Daviess county 5 miles south of Bethany over rural land and then dissipated. | |||||||||||
| 45.0 | 1985-09-22 | 2 | 40°52'N / 93°29'W | 0.50 Mile | 50 Yards | 0 | 0 | 2.5M | 0 | Wayne | |
| 45.1 | 1973-04-19 | 2 | 40°09'N / 94°19'W | 40°10'N / 94°17'W | 0 | 0 | 3K | 0 | Gentry | ||
| 45.3 | 1984-06-07 | 2 | 41°10'N / 95°04'W | 41°27'N / 94°45'W | 23.00 Miles | 150 Yards | 0 | 8 | 2.5M | 0 | Cass |
| 45.7 | 1958-11-17 | 2 | 40°12'N / 93°56'W | 40°16'N / 93°54'W | 4.10 Miles | 100 Yards | 0 | 0 | 250K | 0 | Harrison |
| 46.4 | 1970-04-29 | 2 | 40°35'N / 93°31'W | 40°37'N / 93°29'W | 2.30 Miles | 800 Yards | 0 | 0 | 2.5M | 0 | Wayne |
| 46.5 | 1954-05-31 | 2 | 40°26'N / 95°09'W | 40°27'N / 95°01'W | 6.80 Miles | 440 Yards | 0 | 0 | 25K | 0 | Morgan |
| 46.5 | 1954-04-05 | 3 | 40°36'N / 95°14'W | 40°40'N / 95°10'W | 5.20 Miles | 667 Yards | 0 | 0 | 0K | 0 | Page |
| 47.1 | 1959-09-26 | 2 | 40°19'N / 93°45'W | 40°21'N / 93°39'W | 5.40 Miles | 50 Yards | 0 | 0 | 25K | 0 | Mercer |
| 47.7 | 1975-06-18 | 2 | 40°40'N / 95°14'W | 0 | 0 | 25K | 0 | Page | |||
| 47.7 | 1959-05-10 | 2 | 40°31'N / 95°10'W | 0.20 Mile | 17 Yards | 0 | 0 | 25K | 0 | Nodaway | |
| 47.9 | 1953-06-27 | 5 | 41°27'N / 94°42'W | 1 | 2 | 250K | 0 | Adair | |||
| 47.9 | 1973-04-19 | 2 | 40°05'N / 94°24'W | 40°09'N / 94°19'W | 5.90 Miles | 50 Yards | 0 | 0 | 3K | 0 | Gentry |
| 48.0 | 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 |
| 48.2 | 1955-04-23 | 2 | 40°38'N / 95°14'W | 1.50 Miles | 30 Yards | 0 | 0 | 25K | 0 | Page | |
| 48.5 | 1959-09-26 | 2 | 40°21'N / 93°39'W | 40°22'N / 93°37'W | 0 | 0 | 25K | 0 | Mercer | ||
| 48.7 | 1956-05-29 | 2 | 41°21'N / 94°57'W | 41°23'N / 94°53'W | 3.30 Miles | 50 Yards | 0 | 0 | 0K | 0 | Cass |
| 48.7 | 1980-06-02 | 4 | 40°36'N / 93°36'W | 40°35'N / 93°19'W | 14.70 Miles | 33 Yards | 0 | 0 | 2.5M | 0 | Wayne |
| 48.9 | 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. | |||||||||||
| 49.2 | 1950-05-08 | 2 | 41°02'N / 95°16'W | 41°01'N / 95°13'W | 0 | 0 | 0K | 0 | Montgomery | ||
| 49.2 | 1966-05-23 | 2 | 40°27'N / 95°13'W | 40°28'N / 95°06'W | 5.70 Miles | 50 Yards | 0 | 0 | 25K | 0 | Atchison |
| 49.7 | 1986-06-29 | 2 | 41°31'N / 94°32'W | 2.00 Miles | 73 Yards | 0 | 0 | 250K | 0 | Guthrie | |
* 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.