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Allerton, IA Natural Disasters and Weather Extremes

 
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The chance of earthquake damage in Allerton is about the same as Iowa average and is much lower than the national average. The risk of tornado damage in Allerton is lower than Iowa average and is much higher than the national average.

Topics:Earthquake IndexVolcano IndexTornado IndexOther Weather Extremes EventsVolcanos NearbyHistorical Earthquake EventsHistorical Tornado Events

Earthquake Index, #492

Allerton, 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

Allerton, 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, #748

Allerton, IA
209.11
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 2,897 other weather extremes events within 50 miles of Allerton, IA were recorded from 1950 to 2010. The following is a break down of these events:

TypeCountTypeCountTypeCountTypeCountTypeCount
Avalanche:0Blizzard:28Cold:22Dense Fog:1Drought:11
Dust Storm:0Flood:492Hail:1,022Heat:16Heavy Snow:64
High Surf:0Hurricane:0Ice Storm:34Landslide:0Strong Wind:66
Thunderstorm Winds:912Tropical Storm:0Wildfire:0Winter Storm:45Winter Weather:34
Other:150 

Volcanos Nearby

No volcano is found in or near Allerton, IA.

Historical Earthquake Events

No historical earthquake events that had recorded magnitudes of 3.5 or above found in or near Allerton, IA.

No historical earthquake events found in or near Allerton, IA.

Historical Tornado Events

A total of 78 historical tornado events that had recorded magnitude of 2 or above found in or near Allerton, IA.

Distance (miles)DateMagnitudeStart Lat/LogEnd Lat/LogLengthWidthFatalitiesInjuriesProperty DamageCrop DamageAffected County
4.01980-06-02240°39'N / 93°25'W40°39'N / 93°19'W4.70 Miles80 Yards00250K0Wayne
4.61984-06-07440°44'N / 93°32'W40°49'N / 93°13'W19.00 Miles250 Yards0025.0M0Wayne
5.01991-04-26240°42'N / 93°22'W40°51'N / 93°18'W9.00 Miles60 Yards00250K0Wayne
9.11988-05-08240°37'N / 93°20'W40°42'N / 93°05'W9.00 Miles43 Yards00250K0Wayne
9.31980-06-02440°36'N / 93°36'W40°35'N / 93°19'W14.70 Miles33 Yards002.5M0Wayne
10.21970-04-29240°35'N / 93°31'W40°37'N / 93°29'W2.30 Miles800 Yards002.5M0Wayne
10.41991-04-26240°38'N / 93°16'W40°51'N / 93°05'W15.00 Miles77 Yards022.5M0Wayne
12.11960-04-16240°48'N / 93°18'W40°54'N / 93°10'W9.50 Miles200 Yards0025K0Wayne
12.51985-09-22240°52'N / 93°29'W0.50 Mile50 Yards002.5M0Wayne
14.01953-05-10440°52'N / 93°20'W40°56'N / 93°14'W6.40 Miles33 Yards0025K0Wayne
14.01984-06-07440°49'N / 93°13'W40°51'N / 93°06'W7.00 Miles250 Yards0025.0M0Lucas
14.31961-04-23240°43'N / 93°44'W40°43'N / 93°33'W9.30 Miles600 Yards022.5M0Decatur
17.51960-04-16240°28'N / 93°25'W40°30'N / 93°01'W20.90 Miles100 Yards0025K0Mercer
17.91973-04-21440°26'N / 93°23'W40°28'N / 93°19'W3.60 Miles440 Yards00250K0Putnam
18.51984-06-07440°35'N / 93°54'W40°44'N / 93°32'W22.00 Miles250 Yards0025.0M0Decatur
18.71959-05-20440°42'N / 93°09'W40°52'N / 92°54'W17.20 Miles440 Yards05250K0Wayne
20.01964-06-22240°44'N / 93°45'W1.00 Mile200 Yards00250K0Decatur
20.21961-04-23240°43'N / 93°33'W40°41'N / 92°25'W59.30 Miles600 Yards002.5M0Wayne
21.51980-06-02440°37'N / 93°55'W40°36'N / 93°36'W16.50 Miles140 Yards002.5M0Decatur
22.61967-06-09241°02'N / 93°19'W2.00 Miles400 Yards0025K0Lucas
23.01973-04-21440°20'N / 93°33'W40°26'N / 93°23'W11.00 Miles440 Yards01250K0Mercer
24.41988-11-15240°54'N / 93°02'W40°57'N / 92°58'W4.00 Miles60 Yards04250K0Monroe
24.61970-04-29240°25'N / 93°59'W40°35'N / 93°31'W27.00 Miles440 Yards00250K0Harrison
25.41975-05-07240°49'N / 93°50'W0025K0Decatur
26.41960-04-16240°30'N / 93°01'W40°32'N / 92°51'W8.70 Miles100 Yards0025K0Mercer
27.91959-09-26240°21'N / 93°39'W40°22'N / 93°37'W0025K0Mercer
28.01970-10-08240°43'N / 92°50'W2.00 Miles150 Yards0025K0Appanoose
28.01988-05-08240°42'N / 93°05'W40°52'N / 92°36'W24.00 Miles43 Yards00250K0Appanoose
28.21989-05-24240°26'N / 93°46'W2.50 Miles73 Yards002.5M0Harrison
28.41999-04-08341°04'N / 93°31'W41°09'N / 93°28'W4.50 Miles120 Yards04250K0Lucas
 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.
29.31989-05-24440°41'N / 93°59'W40°38'N / 93°52'W9.00 Miles300 Yards0025.0M0Decatur
29.41992-07-15240°43'N / 92°50'W40°40'N / 92°47'W3.00 Miles17 Yards00250K0Appanoose
30.01965-09-20241°03'N / 93°46'W41°03'N / 93°41'W3.30 Miles150 Yards00250K0Clarke
31.21959-09-26240°19'N / 93°45'W40°21'N / 93°39'W5.40 Miles50 Yards0025K0Mercer
31.21975-05-07241°02'N / 93°47'W10.00 Miles33 Yards00250K0Clarke
31.31980-06-02240°38'N / 92°55'W40°40'N / 92°38'W14.70 Miles80 Yards052.5M0Appanoose
31.61986-07-13241°01'N / 93°49'W1.00 Mile50 Yards00250K0Clarke
32.41967-06-09241°03'N / 93°47'W41°08'N / 93°40'W7.80 Miles300 Yards00250K0Clarke
32.71984-06-07440°51'N / 93°06'W41°10'N / 92°40'W26.00 Miles250 Yards0025.0M0Monroe
33.31964-06-22240°56'N / 93°59'W41°03'N / 93°47'W12.80 Miles400 Yards00250K0Clarke
34.71984-06-07440°25'N / 94°02'W40°34'N / 93°54'W10.00 Miles200 Yards112.5M0Harrison
35.91961-09-01240°42'N / 92°41'W1.00 Mile30 Yards00250K0Appanoose
36.31973-04-19241°06'N / 93°50'W2.00 Miles400 Yards0025K0Clarke
38.41962-05-28241°10'N / 93°12'W41°18'N / 93°03'W11.70 Miles200 Yards00250K0Marion
39.21990-07-25240°49'N / 94°08'W40°51'N / 94°04'W4.00 Miles73 Yards00250K0Ringgold
39.51972-06-05241°13'N / 93°00'W41°11'N / 92°58'W1.90 Miles200 Yards0025K0Marion
39.71958-11-17240°03'N / 93°27'W40°13'N / 93°16'W14.90 Miles50 Yards00250K0Grundy
39.91955-05-26240°26'N / 92°41'W40°36'N / 92°37'W11.70 Miles27 Yards0225K0Schuyler
40.01984-06-07240°41'N / 94°14'W40°44'N / 94°02'W14.00 Miles150 Yards132.5M0Ringgold
40.62001-04-11240°56'N / 94°04'W41°03'N / 94°02'W11.50 Miles150 Yards00150K0Union
 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.
40.71980-06-02240°40'N / 92°38'W40°43'N / 92°33'W5.10 Miles33 Yards002.5M0Davis
40.81967-04-21240°07'N / 93°25'W40°07'N / 93°20'W3.60 Miles50 Yards0025K0Grundy
41.01967-04-21240°07'N / 93°20'W40°07'N / 93°16'W2.70 Miles50 Yards0725K0Grundy
41.22008-05-30241°13'N / 93°07'W41°15'N / 92°52'W12.00 Miles900 Yards010750K25KMarion
 Brief Description: EVENT NARRATIVE: Several homes were damaged or destroyed, two mobile homes were destroyed. Considerable tree damage was reported. The EF2 damage occurred in the Attica area, along with 10 injuries. The tornado moved out of Marion County into Mahaska County. EPISODE NARRATIVE: A very unstable airmass moved into Iowa during the day on the 29th as a warm front lifted north into the state during the afternoon. Low pressure approached from the west, along with a cold front so that the triple point was near the western Iowa, eastern Nebraska area by late afternoon. Thunderstorms erupted quickly during the late afternoon and evening hours in the unstable airmass. By evening, the low level jet was in the 40 to 60 kt range, feeding moisture into the state and pushing precipitable water values to around 200% of normal, in the 1.5 to 1.8 inch range. MUCAPE reached 3000 to 3500 J/kg over western Iowa, with lifted indices in the -6 to -10 C. range. The freezing level was quite high, limiting the hail size somewhat with this event, at 14,300 feet. The available CAPE in the -10 to -30 C. layer of the atmosphere was in the 300 to 500 J/kg range. The DCAPE was between 800 and 1000 J/kg. The environment was highly sheared with 50 to 65 kts of shear available during the event. The LCL was also quite low, in the 750 to 1250 meter range. Thunderstorms erupted over western Iowa stretching into north central Iowa first. It did not take long for the storms to become severe with hail and high winds. Most of the hail reported was in the pea to marble size, with the larger stones in the nickel to quarter size range. The primary mode of severe weather was high winds and several tornadoes. The secondary, but significant threat, was heavy rainfall. A band of 3 to 5 inches of rain fell between U.S. Highway 30 and U.S. Highway 20 during the event. The heaviest rainfall total was in Greene County at Jefferson, with 5.90 inches. Tornadoes began to touch down in western Iowa in Crawford County with two brief touchdowns. One was west of Dow City, causing roof and shingle damage to a farmhouse there. The next was east of Denison where a barn roof was removed and a trailer house was destroyed. A tornado in Carroll County caused damage to 3 farmsteads southeast of Templeton. A machine shed was completely destroyed and numerous other buildings sustained damage. Trees also had substantial damage. Two tornadoes touched down in Calhoun County. One near Farnhamville, tore the roof off of a home and downed power lines. The second caused damage to trees, outbuildings, and power lines on four farmsteads. Farther south, a brief touchdown was reported in Dallas County in open fields west of Minburn. Another tornado touched down in Dallas County later on, west of Adel, and was on the ground for about 4 miles. A more substantial tornado touched down near Murray in Clarke County with one reported on the ground for about 9 miles. As the storms moved east, another tornado was on the ground for over 10 miles in Warren and Marion Counties. The most significant tornado occurred in Marion and Mahaska Counties where an EF2 tornado was on the ground for about 18 miles. Several homes were damaged along its path, two mobile homes were destroyed, and considerable damage was done to trees in the area. Up to 10 people were injured with this tornado, mainly in Attica. The official damage count from this tornado included 5 homes destroyed, 15 with major damage, and another 25 with minor damage. Many of the storms produced high winds with several reports of winds in the 65 to 75 MPH range. Considerable tree damage was reported and some structural damage, mainly outbuildings and shingle damage. Two cars were blown off of the road east of Manning by the high winds. Building debris was blown onto Highway D60 near Gowrie, causing a brief closure. High winds in Butler County blew down a machine shed and barn southwest of Aplington, very near to where an EF5 tornado struck just days before. Extensive damage was done to a farmstead there with some damage done to the house itself as well. Lightning struck a man in Carroll. The lightning bolt hit his driveway, blowing out a chunk of concrete out of the driveway and also injured the man. He was taken to hospital, treated, and released with minor injuries. Flooding became a significant issue after the heavy rainfall of the previous few days. Extensive river flooding occurred across the central third of the state. Record crests were recorded on the Iowa River at Marshalltown.
41.82001-04-11340°34'N / 94°14'W40°53'N / 94°06'W23.50 Miles500 Yards001.5M0Ringgold
 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.
41.91965-04-10240°05'N / 93°42'W40°11'N / 93°33'W10.30 Miles100 Yards01250K0Grundy
42.12001-04-11241°04'N / 94°01'W41°11'N / 93°54'W10.00 Miles150 Yards00125K0Clarke
 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.
42.41964-06-14240°40'N / 92°40'W40°44'N / 92°27'W11.90 Miles200 Yards00250K0Appanoose
42.81981-05-23240°42'N / 94°19'W40°49'N / 94°03'W15.90 Miles130 Yards00250K0Ringgold
43.01988-05-08240°52'N / 92°36'W40°55'N / 92°34'W3.00 Miles43 Yards00250K0Davis
43.01960-04-16340°22'N / 94°13'W40°25'N / 93°56'W15.10 Miles300 Yards0425K0Harrison
43.11964-04-26240°54'N / 94°16'W40°59'N / 94°00'W14.80 Miles300 Yards0025K0Union
43.31999-04-08241°09'N / 93°31'W41°31'N / 93°21'W22.50 Miles150 Yards0070K0Warren
 Brief Description: intermittent track As mentioned in the narrative above, an intense low pressure formed to the southwest of Iowa. The low tracked northeast and lifted into eastern Nebraska. Ahead of the low, a strong low level jet of around 60 knots continued through the day. A nearly stationary frontal boundary extended east from the low. It lifted into southeast Nebraska during the day, but made little progress into southern Iowa. Lines of thunderstorms formed along the boundary through the day and lifted north rapidly. These storms were elevated in nature and as a result produced most of their severe weather in the form of hail. As the day unfolded, a sharp dry line was clearly evident on the satellite as early as 1600 UTC across Kansas. This line raced east during the day. By afternoon, a speed max had rotated around the upper low to the southwest with wind speeds measured by the Lathrop wind profiler at 100 knots at 500 mb by mid afternoon. Jet stream winds were in excess of 120 knots at the same time. Combined with the dynamic situation mentioned above, considerable moisture convergence took place near the triple point between the warm front and the dry line. Surface dew points pooled into to the mid 60s to even a few 70 degree F. dew point readings over northwest Missouri, southeast Nebraska, and southwest Iowa. Meanwhile, dew points fell into the upper 20s over northeast Kansas and south central Nebraska behind the dry line, with teens over central and south central Kansas. Thunderstorms erupted along the dry line by mid day and advanced east through the afternoon. Low level helicity values topped out between 500 and 600 (m/s)**2 just before the first tornadoes formed. Most of the storms in the warm sector became tornadic quickly. The northern limit of the tornado tracks extended about 10 miles or so north of the warm front. Tracks became intermittent very quickly as soon as the storms crossed the surface warm front due to the layer of very cold air just north of the front. Surface temperatures on the cold side of the front were only in the upper 40s to mid 50s. The entire day was very active. Initially, warm air advection thunderstorms produced hail at many locations of central and northern Iowa. Most of is was just below severe levels however. The activity that developed during the afternoon was a combination of warm air advection and the approach of the dryline. At the beginning of the event, the main weather feature was in the form of hail. There were numerous reports of hail three quarters to one and three quarters inch in diameter. The largest hail fell in Guthrie and Dallas Counties with reports of golf ball size hail. One of the storms in the initial wave of afternoon activity became stronger as it moved into southern Story County. Initially, high winds of 60 MPH or more swept through Sheldahl area of Boone County. Greene County was also affected by high winds from the storms. A tornado dropped out of the storm as it moved into the Slater area and was on the ground for about 2 miles. Initial estimates showed 44 homes and businesses damaged in Story County, one was destroyed with major damage to another. Thirty six homes and four businesses were damaged in the town of Slater. Two people were injured during the passage of the tornado. One of the injuries involved a 70 year old man who was picked up by the tornadoes winds and thrown about 10 feet before he latched on to something. His shoulder was dislocated and he required 6 stitches due to his injuries in his hand. High winds northeast of Slater knocked several cars of a Burlington Northern freight train off the tracks after they were blown more than one quarter mile down the track. It was not possible to determine of the cars were knocked off by the tornado or high winds however. This band of storms continue to race and develop northeast through the afternoon. Damage became more sporadic, however high winds occurred as far northeast as Hardin County, with 70 MPH winds reported near New Providence. Hail reports came in from as far northeast as Grundy and Black Hawk Counties, though it was only three quarters of an inch in diameter. Attention then shifted to the tornadic storms that formed near the dry line. During the afternoon, six more tornadoes touched down in Iowa, several of which were long track tornadoes. The first touched down in Taylor County and tracked through Adams, Cass, and Adair Counties. This tornado had was an F4 intensity tornado in parts of Adair and Adams Counties. Damage was extensive with $1,000,000 damage reported in both Adams and Adair Counties. Entire farmsteads were swept clean by the tornado. At one time this tornado was a mile wide wedge with a damage path nearly two miles wide due to the circulation around the tornado. Eyewitness reports indicated that the tornado split into two distinct tornadoes at times, similar to what occurred with the intense F4 tornado in Adair County of 27 May 1995. One of the farmsteads hit near Nodaway was levelled. Reports indicated that a check was blown from the house nearly 100 miles and was found in the town of Jefferson in Greene County. Other checks and papers were found strewn along the path, stretching from Jefferson all the way back to northwest Taylor County. In Adair County, one account indicated pieces of sheet metal from one farm was lifted and deposited six miles away from the farm. Two people were injured by this tornado, one in Adams County with the other in Adair County. One of the injuries Adair County was serious as a man suffered a broken back when the tornado lifted his semi-tractortrailer truck from the Interstate and threw it into a nearby field. The other injuries from this tornado were minor enough that the people were taken to the hospital, treated, and released. There was one account of a horse being picked up by the tornado. It was lifted into the air and thrown through a stand of pine trees 40 feet high. The horse suffered serious injuries and required significant medical attention do to lacerations. The horse amazingly did survive against all odds, though was said would likely lose sight in one eye. The next tornado touched down in Union County and tracked across Madison and Dallas Counties. This tornado had an F4 strength in Union and decreased to a strong F2 in Madison Counties before intensifying again to near F3 strength as it headed into Dallas County. Damage in Union County was around $2,000,000, and around $350,000 in Madison County. There was one person injured by this tornado in Union County. In an amazing account, the Union County Sheriff reported watching as the tornado lifted the car in front of him 35 feet in the air and throwing it 250 feet. The driver was inside during this time and came out of the situation uninjured. Five coal cars were knocked off the tracks in Union County by the tornado as well. This tornado also had a double structure. From eye witness accounts, which also can be shown on Doppler radar imagery, suggest a small rope like tornado passed through the Twelve Mile Lake area shortly before the passage of the main tornado. The next tornado was a weak tornado which touched down about 4 miles west of downtown Des Moines. The tornado did little damage, but did affect one house and several trees. The tornado was seen by a local television sky camera. A short time later, an F2 tornado touched down in Warren County and tracked into southeast Polk County. The track was over rural areas and damage from it was relatively minor. A more significant F3 tornado tracked from northern Lucas County, and weakened to an F2 as it moved across Warren, part of marion, and into Jasper County. One house was destroyed in Lucas County with the four people inside sustaining minor injuries. Once again, this tornado tracked across mostly rural areas, though it did hit a business and two homes in Jasper County and did $1,000,000 in damage. One person was injured in Jasper County. The last tornado touched down in Davis County at Bloomfield and tracked northeast into Wapello County with a maximum strength of F3. Damage in Davis County was over $500,000 as 64 homes and businesses were damaged in the Bloomfield area. To the northeast, the area of the tornado track was mostly rural and damage was limited to outbuildings for the most part. One farmstead reported severe damage near Floris in Davis County. The house was nearly levelled and several outbuildings were completely destroyed. Parts of the house and outbuildings were found as far as 5 miles away from the farmstead. As the storms moved north, high winds were produced over Story County east of Story City. High winds toppled a tractor semi-trailer truck east of Story City on Interstate 35, injuring the driver. Two cars and a truck were also blown off Interstate 35 in Hamilton County. Four people were injured. Two were taken to the hospital, treated, and released. Two were listed in serious condition, one with a neck fracture, the other with a shoulder fracture. The later incident appeared to be from the rear flank downdraft behind the storm and not the initial gust front. From the preliminary data, 178 homes and business were damaged or destroyed by the tornadic storms as well as countless outbuildings. There were several reports of livestock loss as well. It is truly amazing that there was no loss of life during this event and even more amazing is the fact that the injuries that did occur were all minor. Twenty counties in Iowa experienced serious damage from the storms of the day. Iowa Governor Vilsack declared several counties in Iowa disaster areas. These included Taylor, Union, Adams, and Adair Counties. High winds accompanied the storms as the moved through Appanoose County. A local gas station recorded an 81 MPH wind gust as the storms cut a half mile wide swath of destruction west of Moravia. There were numerous reports of cattle killed by the storms. Some were killed by the tornadoes and flying debris, others by lightning. Reports in Adair County, northwest of Fontanelle indicated about 25 head of cattle were struck by lightning shortly before a tornado moved through that area. As the area of storms that produced the high winds north of Ames in central Iowa moved north, they lost their punch. A few of the storms did remain quite strong however. As the area of thunderstorms moved through Cerro Gordo County, high winds blew down a 60 foot corn crib and did some other damage on a farm near Rockwell.
43.61958-11-17240°12'N / 93°56'W40°16'N / 93°54'W4.10 Miles100 Yards00250K0Harrison
43.91966-10-14341°32'N / 93°06'W41°07'N / 93°14'W29.50 Miles200 Yards0025K0Jasper
43.91965-09-20240°43'N / 92°36'W40°50'N / 92°28'W10.30 Miles150 Yards00250K0Davis
44.71989-05-24440°53'N / 94°27'W40°41'N / 93°59'W26.00 Miles300 Yards0025.0M0Ringgold
44.71979-03-29341°10'N / 94°01'W41°16'N / 93°47'W13.60 Miles500 Yards010K0Madison
44.92010-06-01240°48'N / 94°13'W40°49'N / 94°13'W2.00 Miles250 Yards004.0M10KRinggold
 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.
45.41972-06-13241°07'N / 94°03'W2.00 Miles100 Yards0025K0Union
45.61979-03-29341°16'N / 93°47'W41°22'N / 93°38'W9.90 Miles500 Yards010K0Warren
45.91999-04-08241°11'N / 93°45'W41°30'N / 93°31'W25.00 Miles100 Yards0075K0Warren
 Brief Description: very intermittent track in rural areas As mentioned in the narrative above, an intense low pressure formed to the southwest of Iowa. The low tracked northeast and lifted into eastern Nebraska. Ahead of the low, a strong low level jet of around 60 knots continued through the day. A nearly stationary frontal boundary extended east from the low. It lifted into southeast Nebraska during the day, but made little progress into southern Iowa. Lines of thunderstorms formed along the boundary through the day and lifted north rapidly. These storms were elevated in nature and as a result produced most of their severe weather in the form of hail. As the day unfolded, a sharp dry line was clearly evident on the satellite as early as 1600 UTC across Kansas. This line raced east during the day. By afternoon, a speed max had rotated around the upper low to the southwest with wind speeds measured by the Lathrop wind profiler at 100 knots at 500 mb by mid afternoon. Jet stream winds were in excess of 120 knots at the same time. Combined with the dynamic situation mentioned above, considerable moisture convergence took place near the triple point between the warm front and the dry line. Surface dew points pooled into to the mid 60s to even a few 70 degree F. dew point readings over northwest Missouri, southeast Nebraska, and southwest Iowa. Meanwhile, dew points fell into the upper 20s over northeast Kansas and south central Nebraska behind the dry line, with teens over central and south central Kansas. Thunderstorms erupted along the dry line by mid day and advanced east through the afternoon. Low level helicity values topped out between 500 and 600 (m/s)**2 just before the first tornadoes formed. Most of the storms in the warm sector became tornadic quickly. The northern limit of the tornado tracks extended about 10 miles or so north of the warm front. Tracks became intermittent very quickly as soon as the storms crossed the surface warm front due to the layer of very cold air just north of the front. Surface temperatures on the cold side of the front were only in the upper 40s to mid 50s. The entire day was very active. Initially, warm air advection thunderstorms produced hail at many locations of central and northern Iowa. Most of is was just below severe levels however. The activity that developed during the afternoon was a combination of warm air advection and the approach of the dryline. At the beginning of the event, the main weather feature was in the form of hail. There were numerous reports of hail three quarters to one and three quarters inch in diameter. The largest hail fell in Guthrie and Dallas Counties with reports of golf ball size hail. One of the storms in the initial wave of afternoon activity became stronger as it moved into southern Story County. Initially, high winds of 60 MPH or more swept through Sheldahl area of Boone County. Greene County was also affected by high winds from the storms. A tornado dropped out of the storm as it moved into the Slater area and was on the ground for about 2 miles. Initial estimates showed 44 homes and businesses damaged in Story County, one was destroyed with major damage to another. Thirty six homes and four businesses were damaged in the town of Slater. Two people were injured during the passage of the tornado. One of the injuries involved a 70 year old man who was picked up by the tornadoes winds and thrown about 10 feet before he latched on to something. His shoulder was dislocated and he required 6 stitches due to his injuries in his hand. High winds northeast of Slater knocked several cars of a Burlington Northern freight train off the tracks after they were blown more than one quarter mile down the track. It was not possible to determine of the cars were knocked off by the tornado or high winds however. This band of storms continue to race and develop northeast through the afternoon. Damage became more sporadic, however high winds occurred as far northeast as Hardin County, with 70 MPH winds reported near New Providence. Hail reports came in from as far northeast as Grundy and Black Hawk Counties, though it was only three quarters of an inch in diameter. Attention then shifted to the tornadic storms that formed near the dry line. During the afternoon, six more tornadoes touched down in Iowa, several of which were long track tornadoes. The first touched down in Taylor County and tracked through Adams, Cass, and Adair Counties. This tornado had was an F4 intensity tornado in parts of Adair and Adams Counties. Damage was extensive with $1,000,000 damage reported in both Adams and Adair Counties. Entire farmsteads were swept clean by the tornado. At one time this tornado was a mile wide wedge with a damage path nearly two miles wide due to the circulation around the tornado. Eyewitness reports indicated that the tornado split into two distinct tornadoes at times, similar to what occurred with the intense F4 tornado in Adair County of 27 May 1995. One of the farmsteads hit near Nodaway was levelled. Reports indicated that a check was blown from the house nearly 100 miles and was found in the town of Jefferson in Greene County. Other checks and papers were found strewn along the path, stretching from Jefferson all the way back to northwest Taylor County. In Adair County, one account indicated pieces of sheet metal from one farm was lifted and deposited six miles away from the farm. Two people were injured by this tornado, one in Adams County with the other in Adair County. One of the injuries Adair County was serious as a man suffered a broken back when the tornado lifted his semi-tractortrailer truck from the Interstate and threw it into a nearby field. The other injuries from this tornado were minor enough that the people were taken to the hospital, treated, and released. There was one account of a horse being picked up by the tornado. It was lifted into the air and thrown through a stand of pine trees 40 feet high. The horse suffered serious injuries and required significant medical attention do to lacerations. The horse amazingly did survive against all odds, though was said would likely lose sight in one eye. The next tornado touched down in Union County and tracked across Madison and Dallas Counties. This tornado had an F4 strength in Union and decreased to a strong F2 in Madison Counties before intensifying again to near F3 strength as it headed into Dallas County. Damage in Union County was around $2,000,000, and around $350,000 in Madison County. There was one person injured by this tornado in Union County. In an amazing account, the Union County Sheriff reported watching as the tornado lifted the car in front of him 35 feet in the air and throwing it 250 feet. The driver was inside during this time and came out of the situation uninjured. Five coal cars were knocked off the tracks in Union County by the tornado as well. This tornado also had a double structure. From eye witness accounts, which also can be shown on Doppler radar imagery, suggest a small rope like tornado passed through the Twelve Mile Lake area shortly before the passage of the main tornado. The next tornado was a weak tornado which touched down about 4 miles west of downtown Des Moines. The tornado did little damage, but did affect one house and several trees. The tornado was seen by a local television sky camera. A short time later, an F2 tornado touched down in Warren County and tracked into southeast Polk County. The track was over rural areas and damage from it was relatively minor. A more significant F3 tornado tracked from northern Lucas County, and weakened to an F2 as it moved across Warren, part of marion, and into Jasper County. One house was destroyed in Lucas County with the four people inside sustaining minor injuries. Once again, this tornado tracked across mostly rural areas, though it did hit a business and two homes in Jasper County and did $1,000,000 in damage. One person was injured in Jasper County. The last tornado touched down in Davis County at Bloomfield and tracked northeast into Wapello County with a maximum strength of F3. Damage in Davis County was over $500,000 as 64 homes and businesses were damaged in the Bloomfield area. To the northeast, the area of the tornado track was mostly rural and damage was limited to outbuildings for the most part. One farmstead reported severe damage near Floris in Davis County. The house was nearly levelled and several outbuildings were completely destroyed. Parts of the house and outbuildings were found as far as 5 miles away from the farmstead. As the storms moved north, high winds were produced over Story County east of Story City. High winds toppled a tractor semi-trailer truck east of Story City on Interstate 35, injuring the driver. Two cars and a truck were also blown off Interstate 35 in Hamilton County. Four people were injured. Two were taken to the hospital, treated, and released. Two were listed in serious condition, one with a neck fracture, the other with a shoulder fracture. The later incident appeared to be from the rear flank downdraft behind the storm and not the initial gust front. From the preliminary data, 178 homes and business were damaged or destroyed by the tornadic storms as well as countless outbuildings. There were several reports of livestock loss as well. It is truly amazing that there was no loss of life during this event and even more amazing is the fact that the injuries that did occur were all minor. Twenty counties in Iowa experienced serious damage from the storms of the day. Iowa Governor Vilsack declared several counties in Iowa disaster areas. These included Taylor, Union, Adams, and Adair Counties. High winds accompanied the storms as the moved through Appanoose County. A local gas station recorded an 81 MPH wind gust as the storms cut a half mile wide swath of destruction west of Moravia. There were numerous reports of cattle killed by the storms. Some were killed by the tornadoes and flying debris, others by lightning. Reports in Adair County, northwest of Fontanelle indicated about 25 head of cattle were struck by lightning shortly before a tornado moved through that area. As the area of storms that produced the high winds north of Ames in central Iowa moved north, they lost their punch. A few of the storms did remain quite strong however. As the area of thunderstorms moved through Cerro Gordo County, high winds blew down a 60 foot corn crib and did some other damage on a farm near Rockwell.
46.01975-06-18241°22'N / 93°30'W003K0Warren
46.31958-10-08340°27'N / 94°13'W40°27'N / 94°09'W3.00 Miles300 Yards00250K0Harrison
47.01979-03-29340°46'N / 94°23'W41°10'N / 94°01'W33.50 Miles500 Yards022.5M0Union
47.41988-05-08240°55'N / 92°34'W40°56'N / 92°27'W11.00 Miles43 Yards00250K0Wapello
47.71960-06-16241°23'N / 93°34'W2.00 Miles150 Yards0025K0Warren
49.12004-05-29440°12'N / 94°02'W40°13'N / 94°02'W2.00 Miles800 Yards0000Harrison
 Brief Description: Large F4 tornado crossed into Harrison county from Daviess county 5 miles south of Bethany over rural land and then dissipated.


* 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.


 
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