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USA.com / Iowa / Pottawattamie County / Natural Disasters and Weather Extremes

Pottawattamie County Natural Disasters and Weather Extremes

 
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The chance of earthquake damage in Pottawattamie County is about the same as Iowa average and is much lower than the national average. The risk of tornado damage in Pottawattamie County 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, #19

Pottawattamie County
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

Pottawattamie County
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, #58

Pottawattamie County
215.31
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 14,842 other weather extremes events within 50 miles of Pottawattamie County were recorded from 1950 to 2010. The following is a break down of these events:

TypeCountTypeCountTypeCountTypeCountTypeCount
Avalanche:0Blizzard:93Cold:152Dense Fog:14Drought:30
Dust Storm:1Flood:1,275Hail:6,523Heat:45Heavy Snow:131
High Surf:0Hurricane:0Ice Storm:85Landslide:0Strong Wind:183
Thunderstorm Winds:5,315Tropical Storm:0Wildfire:0Winter Storm:304Winter Weather:141
Other:550 

Volcanos Nearby

No volcano is found in or near Pottawattamie County.

Historical Earthquake Events

No historical earthquake events that had recorded magnitudes of 3.5 or above found in or near Pottawattamie County.

No historical earthquake events found in or near Pottawattamie County.

Historical Tornado Events

A total of 82 historical tornado events that had recorded magnitude of 2 or above found in or near Pottawattamie County.

Distance (miles)DateMagnitudeStart Lat/LogEnd Lat/LogLengthWidthFatalitiesInjuriesProperty DamageCrop DamageAffected County
6.91999-05-16241°12'N / 95°35'W41°17'N / 95°33'W5.00 Miles120 Yards00690K0Pottawattamie
 Brief Description: Destroyed mostly farm buildings and equipment, did damage a few homes.
8.71976-06-26441°27'N / 95°36'W41°29'N / 95°30'W5.10 Miles200 Yards062.5M0Pottawattamie
12.01968-08-18341°15'N / 95°57'W41°15'N / 95°32'W21.30 Miles33 Yards002.5M0Douglas
12.11992-06-16241°21'N / 95°21'W41°24'N / 95°17'W4.00 Miles100 Yards00250K0Pottawattamie
13.72007-05-05241°09'N / 95°22'W41°15'N / 95°21'W7.00 Miles400 Yards000K0KPottawattamie
 Brief Description: EVENT NARRATIVE: This tornado crossed into Pottawattamie county from Montgomery county about 4 miles southeast of Macedonia. The total path length was around 11.5 miles. Although over half of it was in Pottawattamie county, most of the damage was done in Montgomery county where a roof was torn off of a house, barns were destroyed and cars were tossed into a field. EPISODE NARRATIVE: A warm front that was along the Kansas and Nebraska border early Saturday morning May 5th, lifted north during the day bringing widespread heavy rain and severe weather, including tornadoes, to eastern Nebraska and southwest Iowa. The warm front was part of a large upper level system that brought several days of severe weather and flooding to the region. Heavy rain and flooding was reported with some of the activity Saturday morning, along with isolated severe thunderstorm reports. However, during the afternoon the severe weather became more widespread over northeast Nebraska where supercells spawned several tornadoes. At this time, thunderstorms, some severe with heavy rain, produced flash flooding over parts of southeast Nebraska. By evening much of the severe weather, including supercell producing tornadoes, shifted into southwest Iowa, although isolated severe thunderstorms persisted over parts of eastern Nebraska until after midnight CDT.
14.11975-05-06241°24'N / 95°51'W41°32'N / 95°40'W12.80 Miles500 Yards0025K0Pottawattamie
15.51972-09-12241°30'N / 95°42'W41°35'N / 95°39'W5.90 Miles100 Yards0025K0Harrison
17.41988-07-15241°16'N / 95°52'W2.30 Miles100 Yards04225.0M0Pottawattamie
17.41988-07-15341°16'N / 95°52'W2.80 Miles73 Yards03425.0M0Pottawattamie
17.91988-05-07241°20'N / 95°57'W41°27'N / 95°49'W7.20 Miles73 Yards002.5M0Pottawattamie
18.21973-09-25241°33'N / 95°20'W0025K0Shelby
20.41975-05-06241°28'N / 95°52'W41°37'N / 95°48'W10.60 Miles33 Yards0025K0Pottawattamie
20.61970-05-12241°28'N / 95°14'W41°26'N / 95°07'W5.90 Miles400 Yards00250K0Pottawattamie
21.21992-06-16241°09'N / 95°54'W41°09'N / 95°50'W3.00 Miles73 Yards0025K0Mills
21.42007-05-05241°03'N / 95°19'W41°06'N / 95°21'W5.00 Miles400 Yards000K0KMontgomery
 Brief Description: EVENT NARRATIVE: This tornado tore the roof off of a house, destroyed a barn, downed trees and power poles and tossed cars into a field. Most of the damage was in Montgomery county, east of Henderson (which is in Mills county). The tornado crossed into Pottawattamie county about 4 miles southeast of Macedonia. The total path length was around 11.5 miles. EPISODE NARRATIVE: A warm front that was along the Kansas and Nebraska border early Saturday morning May 5th, lifted north during the day bringing widespread heavy rain and severe weather, including tornadoes, to eastern Nebraska and southwest Iowa. The warm front was part of a large upper level system that brought several days of severe weather and flooding to the region. Heavy rain and flooding was reported with some of the activity Saturday morning, along with isolated severe thunderstorm reports. However, during the afternoon the severe weather became more widespread over northeast Nebraska where supercells spawned several tornadoes. At this time, thunderstorms, some severe with heavy rain, produced flash flooding over parts of southeast Nebraska. By evening much of the severe weather, including supercell producing tornadoes, shifted into southwest Iowa, although isolated severe thunderstorms persisted over parts of eastern Nebraska until after midnight CDT.
24.41999-05-16341°36'N / 95°52'W41°40'N / 95°45'W7.50 Miles440 Yards2161.9M0Harrison
 Brief Description: The stronger of the 2 tornadoes that ripped through Harrison county the afternoon of 5/16/99 killed 2 people and destroyed 6 homes and a bridge before it dissipated a couple of miles east of Logan. A family of 5 leaving a high school graduation party encountered the tornado on a road around 6 miles northeast of Missouri Valley and took cover in a ditch about the time the path of the tornado widened to a quarter mile. Two of them were killed after their car and a 3-ton combine head were thrown on them. There were also numerous flipped or smashed vehicles in this area. F37OU, F15OU
25.71999-05-16341°38'N / 95°54'W41°38'N / 95°48'W6.20 Miles200 Yards00100K0Harrison
 Brief Description: The smaller of 2 strong tornadoes that hit Harrison county the afternoon of 5/16/99. This one destroyed a home west of Logan before it weakened, it then made a loop back to the northwest before dissipating.
26.11976-06-13241°25'N / 95°08'W41°30'N / 95°00'W8.50 Miles100 Yards0025K0Cass
26.81975-05-06441°11'N / 96°04'W41°17'N / 96°01'W6.90 Miles267 Yards3118250.0M0Douglas
26.81965-05-25241°24'N / 95°02'W0025K0Cass
26.91950-05-08241°02'N / 95°16'W41°01'N / 95°13'W000K0Montgomery
27.01983-05-06241°34'N / 95°57'W41°45'N / 95°45'W15.00 Miles20 Yards00250K0Harrison
27.31964-08-27241°26'N / 95°02'W1.00 Mile50 Yards0025K0Cass
27.32009-03-23241°33'N / 95°57'W41°40'N / 95°55'W9.00 Miles440 Yards000K0KHarrison
 Brief Description: EVENT NARRATIVE: The tornado touched down near highway 30 about 1.5 miles west of the interchange between Interstate 29 and Highway 30, or about 3 miles west of Missouri Valley Iowa. The tornado was at its strongest and widest within a mile of its touchdown point, becoming weaker with more intermittent damage farther north. Near the touchdown point, a barn sustained roof damage and a windmill was knocked down. One-half mile north of Highway 30, 54 empty grain rail cars were derailed. One mile north of Highway 30, along 305th St., two residences were impacted by the tornado. A 100-year-old single family residence directly in its path was completely destroyed, with all walls collapsed and debris relocated about 50 feet north of the foundation. The debris collected over the site of a cinder block garage, which also partially collapsed. About 100 yards north of the garage site, a machine shed was collapsed onto a combine inside, which had been moved by the wind. Trees near the house sustained some broken limbs and treetops, and a power pole was snapped. The damage at this site was given an EF2 rating. Another residence one-quarter mile to its west sustained minor siding and shingle damage and windows were broken. Seven of the eight outbuildings at that residence were collapsed, with debris strewn into nearby fields. Damage at the two houses indicated a path width of one quarter mile at that point, the widest along the path of the tornado. The tornado continued northward, overturning two semis on Interstate 29. From there to a point about 3 miles southwest of Magnolia, near the intersection of the Loess Hills Trail and Melody Oaks Trail, intermittent light damage to trees and roofs of a couple of outbuildings was noted. From this point, the survey team determined the damage path narrowed to 100 yards or less based on scattered tree and outbuilding damage, with EF0 intensity north of Interstate 29. EPISODE NARRATIVE: An intense upper level low pressure system tracked from eastern Colorado into southeast South Dakota from March 23rd to March 24th. This caused a surface low pressure system to move from western Nebraska into southeast South Dakota during that time. As the low tracked northeast, a dry-line moved into eastern Nebraska during the afternoon of March 23rd. With surface temperatures in the 60s and 70s, and dewpoint temperatures in the 50s, ample instability was in place to allow a line of severe thunderstorms to develop as the dry-line punched eastward. Several fast moving and low-topped supercell thunderstorms were embedded in the line, and one cell produced cyclic tornadoes from southeast of Lincoln into western Iowa. The storms in the line were moving north northeast at between 50 and 60 mph. In addition to the severe weather, strong southerly gradient winds prevailed ahead of the low pressure. In some cases the winds gusted between 50 and 60 mph for several hours across parts of eastern Nebraska.
27.81975-03-27241°15'N / 96°04'W0.50 Mile300 Yards04250K0Douglas
29.41975-05-06441°10'N / 96°04'W41°11'N / 96°04'W1.10 Miles267 Yards015250K0Sarpy
29.41964-04-20341°24'N / 95°03'W41°24'N / 94°55'W6.10 Miles350 Yards0125K0Cass
29.51992-06-16341°39'N / 95°48'W41°52'N / 95°32'W19.00 Miles200 Yards002.5M0Harrison
31.51964-04-20240°54'N / 95°23'W01250K0Montgomery
31.62008-06-08241°11'N / 96°08'W41°13'N / 96°07'W3.00 Miles440 Yards030K0KDouglas
 Brief Description: EVENT NARRATIVE: This is the continuation of tornado number 1 (of 2) to hit the Omaha metro area this night. Tornado number 1 crossed over from Sarpy county near 144th and Harrison Streets before merging with tornado number 2 just east of 132nd and Westwood Lane. From there the merged tornado continued northeast to near 114th and Shirley Streets. Tornado number 1 traveled at about 50 mph in Douglas county. Tornado number 1 produced EF2 damage in both Douglas and Sarpy counties. Although tree and roof damage was noted along most of the track, the area hardest hit in Douglas county was around 137th and Y Streets. A few homes had their roofs completely blown off in this area, while others had significant roof and siding damage. The tornado then hit a Walmart, Sams Club and Home Depot causing damage to each of those businesses after it crossed L Street. Tornado number 1 first set down just southeast of 232nd and West Angus Road about a mile west of Gretna in Sarpy county. It traveled about 8 miles in Sarpy county before crossing into Douglas county. The tornadoes spun up on the leading edge of a bow echo that gathered strength and raced through the Omaha metropolitan region. OPPD reported that 13,800 customers lost power from the storm. In total, more than 500 homeowners reported damage from the storm and according to FEMA, 7 homes were destroyed and 21 others sustained major damage. EPISODE NARRATIVE: As one unseasonably strong upper level system lifted into Canada another one dropped down behind it across the northern Plains. This caused surface low pressure to develop over northeast Kansas along a cold front that was crossing the plains. This in turn caused the front to slow down as it moved into southeast Nebraska and southwest Iowa. A small line of thunderstorms that had developed along the front moved ahead of it and encountered a strong low level jet. The combination of the low level jet, and a warm front that extended east of the low, strengthened the line segment just to the southwest of Omaha and causing it to bow out. In turn a few quick moving spin-up circulations and 2 tornadoes developed as the bow echo crossed the Omaha area. Although these tornadoes hit in the middle of the night and caused significant damage in the Omaha area, there were no deaths or serious injuries with the storm. The system also produced areas of heavy rain which caused some flash flooding and then eventual river flooding.
31.71974-05-13341°08'N / 95°04'W41°13'N / 94°53'W10.90 Miles20 Yards00250K0Montgomery
31.81975-05-07241°39'N / 95°13'W41°48'N / 95°12'W9.90 Miles33 Yards0025K0Shelby
32.01955-05-06241°39'N / 95°19'W41°48'N / 95°05'W15.50 Miles200 Yards0025K0Shelby
32.11990-06-13240°52'N / 95°39'W40°53'N / 95°27'W10.50 Miles67 Yards00250K0Fremont
32.22007-05-06241°10'N / 94°58'W41°15'N / 94°56'W7.00 Miles830 Yards001.0M0KCass
 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.
32.21979-08-28340°55'N / 95°46'W40°52'N / 95°40'W5.60 Miles533 Yards003K0Mills
32.61956-05-29241°21'N / 94°57'W41°23'N / 94°53'W3.30 Miles50 Yards000K0Cass
32.61988-05-07241°11'N / 96°10'W41°12'N / 96°07'W2.50 Miles73 Yards002.5M0Douglas
33.01975-05-07241°49'N / 95°30'W0025K0Crawford
33.11984-06-07241°10'N / 95°04'W41°27'N / 94°45'W23.00 Miles150 Yards082.5M0Cass
35.81976-06-13241°30'N / 95°00'W41°37'N / 94°50'W11.50 Miles33 Yards0025K0Audubon
36.32008-06-08241°08'N / 96°16'W41°11'N / 96°08'W8.00 Miles440 Yards000K0KSarpy
 Brief Description: EVENT NARRATIVE: This was the first touchdown of 2 tornadoes that hit the Omaha metro area this night. Tornado number 1 started just southeast of 232ND and West Angus Road about a mile west of Gretna. A garage was demolished at this point, suggesting EF1 damage. The tornado moved east northeast at 45 mph and produced scattered EF0 damage in Gretna with tree and shingle damage noted. From there tornado number 1 continued northeast to near 156th and Giles Road. EF 2 damage was noted just southwest of that point with major roof damage to a home. The tornado then crossed over into the Millard area of Douglas county where it continued for about 3 more miles before merging with tornado number 2. Tornado 1 also caused EF2 damage in Douglas county with much of it concentrated in the vicinity of 137th and Y Streets. The tornadoes spun up on the leading edge of a bow echo that gathered strength as it raced through the Omaha metropolitan area. More than 500 homeowners reported damage from the storm and OPPD reported that 13,800 customers lost power. EPISODE NARRATIVE: As one unseasonably strong upper level system lifted into Canada another one dropped down behind it across the northern Plains. This caused surface low pressure to develop over northeast Kansas along a cold front that was crossing the plains. This in turn caused the front to slow down as it moved into southeast Nebraska and southwest Iowa. A small line of thunderstorms that had developed along the front moved ahead of it and encountered a strong low level jet. The combination of the low level jet, and a warm front that extended east of the low, strengthened the line segment just to the southwest of Omaha and causing it to bow out. In turn a few quick moving spin-up circulations and 2 tornadoes developed as the bow echo crossed the Omaha area. Although these tornadoes hit in the middle of the night and caused significant damage in the Omaha area, there were no deaths or serious injuries with the storm. The system also produced areas of heavy rain which caused some flash flooding and then eventual river flooding.
37.51953-06-07241°33'N / 96°15'W41°34'N / 96°10'W4.10 Miles33 Yards0125K0Washington
37.91964-06-22340°45'N / 95°36'W40°50'N / 95°29'W8.00 Miles400 Yards00250K0Fremont
38.11959-05-10240°56'N / 95°03'W1.00 Mile200 Yards003K0Montgomery
38.41984-06-12240°52'N / 95°56'W0.50 Mile50 Yards003K0Cass
38.81963-04-18241°10'N / 94°50'W0025K0Cass
38.91988-05-07241°07'N / 96°20'W41°11'N / 96°10'W6.70 Miles73 Yards212.5M0Sarpy
39.11979-08-28340°52'N / 95°40'W40°41'N / 95°22'W19.90 Miles533 Yards2142.5M0Fremont
39.21952-06-02241°54'N / 95°24'W41°53'N / 95°20'W2.30 Miles100 Yards010K0Crawford
39.81964-04-12240°54'N / 95°03'W2.00 Miles150 Yards0025K0Montgomery
40.01964-04-20240°45'N / 95°28'W40°47'N / 95°25'W2.70 Miles300 Yards0025K0Fremont
40.41992-06-16341°52'N / 95°32'W41°59'N / 95°30'W7.00 Miles200 Yards032.5M0Crawford
41.11998-06-29241°55'N / 95°30'W41°56'N / 95°17'W11.00 Miles55 Yards00500K50KCrawford
 Brief Description: A complex weather situation was set up over the central U.S. as a mesoscale convective system passed to the south of Iowa during the overnight hours and early morning of the 29th. Initially, the surface warm front was located to the south of this system. That was not actually the case aloft however. During the predawn hours the surface front surged north and by sunrise was located across northeast Nebraska across northern Iowa. The airmass was very unstable to the south of the front with dew point temperatures will in the 70s F. The initial development of thunderstorms took place during the early part of the day over northeast Nebraska. The storms became severe quickly as they moved and developed eastward into Iowa. By mid morning, the storms had formed a nearly east to west line. Storm relative inflow into the line was around 40 knots. The storms produced a variety of severe weather across Iowa. They initially moved east across the northern and central counties, but then began sinking sinking southeast. The dominant severe weather with the storms was extremely high winds. Damage was very widespread across the state. Winds in excess of 100 MPH were reported with one unofficial wind speed measured at 126 MPH in the town of Washington at 1405 CST. In one unusual story, high winds hit Mahaska County. Three miles south of New Sharon, a puppy was tied to its dog house which was picked up by the wind. The dog house and puppy were lifted over the top of a two car garage and a corn crib. Both were deposited in the farm yard. When found the dog house was upside down and the puppy, though scared, was fine. There were several tornadoes during the event. One of the longer track well defined tornadoes was the initial tornado. It was on the ground for about 11 miles as it swept across Crawford County. Several residences, outbuildings, grain bins, and trees were damaged along its path. Reports indicate that between 30 and 50 residences were damaged by this tornado. There were several small tornadoes in central Iowa. They had short tracks and only touched down briefly. One cut a mile long path east of Marshalltown through a corn field and a grove of trees. Another in Dallas County was on the ground through mostly open country for two miles. High winds were a major problem with these storms. Many places reported winds over 80 MPH with incredible tree damage and numerous buildings damaged or destroyed. At least 38 counties were declared disaster areas by the Federal Government due to the severe damage and flooding. A final total will not be available before publication deadlines, however preliminary data have been included. In the Des Moines County Warning Area these included: Wright, Franklin, Butler, Bremer, Hamilton, Hardin, Grundy, Crawford, Carroll, Greene, Boone, Story, Marshall, Audubon, Guthrie, Dallas, Polk, Jasper, Cass, Adair, Madison, Warren, Marion, Adams, and Taylor. One of the hardest hit Counties was Polk County. Damage appeared to be from straight line winds based on a storm survey that was done following the event. The damage occurred over the southwest semicircle of a large meso low in contact with the ground. Due to the rapid translational speed of 50 to 75 MPH, winds were enhanced on the southwest semicircle of the meso low. Smaller scale winds could have been embedded within this circulation as well. There was little evidence of small scale convergent tornadic damage, however aerial surveys did make some suggestion and eye witness accounts of sightings were quite numerous in the metro Des Moines area. All trees and debris were laid down to the south or southeast. The major damage swath as 3 to 7 miles wide northwest of Camp Dodge, with a widening into a full blown derecho after that. The event was born a few miles northwest of Perry, between Rippey and Berkley in southwest Boone County. The mile wide damage path expanded to over 3 miles by the time it reached full intensity near highway 169 between Woodward and Perry. The path continued through Granger, Camp Dodge, and Johnston. The path was nearly 7 miles wide near Granger. A second, smaller, meso low passed near Madrid, downing power lines. This meso low matured near Jester Park Golf Course, causing significant structural damage to houses. The two meso lows merged near the NWS Forecast Office in Johnston, with two miles of power poles snapped off between Johnston and Granger. Much of the damage along the most severe track was in the F1 intensity category, with speeds in the 75 to 110 MPH range. A few spots along the path, such as in the Granger and Camp Dodge area, sustained sufficient damage to justify F2 winds, 110 to 155 MPH. It appears a tornado or family of tornadoes touched down southeast of Berkley and moved southeast into the Pleasant Hill area just east of Des Moines. The track was intermittent, indicating either one tornado touching down occasionally, or one or more weak tornadoes rotating around the meso circulation. The worst effected metro areas were the Granger area, Johnston, and the northeast side of Des Moines proper. A duplex in Granger was flattened by the winds. There were several reports of roofs being ripped off of stores and houses in the metropolitan Des Moines area. Several small private planes were flipped at a small air field north of Des Moines. There were also several reports of semi-tractortrailer trucks being blown over on Interstate 35. Heavy construction equipment was overturned on Interstate 35/80 just north of Des Moines. Damage was extensive to the east side of Des Moines proper. To make matters worse, following the passage of the main line of thunderstorms, a second line of severe thunderstorms developed and moved across the same areas already hit. The storms were smaller, but did produce brief tornado touch downs and hail up to 2.5 inches in diameter. The second line of storms did eventually combine with the first and moved southeast across the rest of the state. Damage was widespread across the state and it will be months before final numbers are in. Estimates from Polk County alone are near $100 million in damage including cleanup. Totals were still being tallied at this writing, however a few include over $11 million in damage from initial claims in Johnston and $726,000 from West Des Moines just to city buildings and systems. West Des Moines was on the far west edge of the major damage however. In addition to the property damage, at least 125 people were injured during the storm. Most of the injuries were caused by flying debris and many were not serious. Fortunately there were no fatalities. Heavy damage was reported by MidAmerica Energy. On a state wide report, they indicated 200,000 homes were without electricity, effecting over 500,000 people, at one time during the storm. In the metropolitan Des Moines area, 100,000 homes were without electricity at the height of the storm. That number was reduced to around 25,000 36 hours later. The worst damaged areas were without power for 5 to 6 days. Heavy damage was also reported by local telephone and cable systems. In Polk County, the worst damage extended from the Camp Dodge area into the northeast parts of Des Moines. At least 462 homes in the metro Des Moines area sustained significant damage. Statewide, 80 homes were destroyed, 559 sustained severe damage, with 1416 others receiving moderate damage. In the Camp Dodge area, 80 to 90 percent of the brick buildings were damaged with the roofs removed from many of them. Lightning from the storms struck the WSR-88D in the midst of the storm. The radar was taken out of service for more than 24 hours because of this. In addition to the severe weather, flooding quickly became a problem. Iowa soil was nearly saturated as the weather pattern had been very wet for six weeks previous. Although rainfall was not extreme, one to three inches of rain fell over a several county area. This caused widespread urban flooding across north central into central Iowa, though damage from the flooding was not serious. Crop damage was very difficult to determine and will not likely be clear until the fall harvest. Reports from some of the local extension agents say damage to the corn ranged up to 75% destroyed in areas with the highest wind, such as the swath that went through central Iowa in association with the tornado there. No doubt losses will be in the hundreds of thousands of dollars if not in the millions. Accounts of damage were of course too numerous to document here as the areal extent of the storms was very large. Countless reports of parts of crop fields being flattened were received. Semi-tractortrailer trucks were overturned by the high winds both in the Des Moines metro area as well as in Newton. Trees were found on houses over a large part of the state. One news reported wrote "there is not a power pole standing between Fort Dodge and Oskaloosa". Though not figuratively true, this statement does point out the extensive damage that occurred with these storms.l
41.61964-06-19340°43'N / 95°21'W40°50'N / 95°11'W11.50 Miles350 Yards022.5M0Page
42.22008-06-11341°51'N / 96°01'W41°54'N / 95°52'W7.00 Miles440 Yards4480K0KMonona
 Brief Description: EVENT NARRATIVE: This tornado tragically hit a boyscout camp north of Little Sioux Iowa killing 4 young scouts. The tornado initially touched down in Burt county Nebraska, crossed into Harrison county Iowa near mile marker 97 on Interstate 29, and then finally crossed into Monona county Iowa about 4 miles north of Little Sioux. In Monona county the tornado entered the Little Sioux Scout Ranch, destroying the rangers home near the entrance of the park giving it a rating of EF3. The storm then blew down trees and destroyed bunk houses at the camp. Four scouts were killed in one bunk house when a brick chimney collapsed on them. In total 48 people were injured at the camp. The tornado continued to topple trees as it tracked into Preparation Canyon State Park. Just before it entered the park a farmstead sustained damage. The tornado hit another farmstead about 2.5 miles southwest of Moorhead where trees were blown down and sheds damaged. The tornado then began to weaken and finally lifted about 2 miles southwest of Moorhead. The total path length was around 14 miles. EPISODE NARRATIVE: A very strong and unseasonably cold upper level low pressure system that was tracking across the northern plains brought a strong low level jet to the region during the early morning hours of June 11th. The warm and unstable air that worked north into the region helped spawn early morning severe thunderstorms across eastern Nebraska and southwest Iowa. Later that day as the upper level system worked into the central Dakotas, a cold front pushed across the region. This helped set off another round of thunderstorms that developed over east central Nebraska by late afternoon. Isolated small supercell thunderstorms initially developed ahead of the cold front over eastern Nebraska, but they were quickly overtaken by a broken line of larger supercell thunderstorms, some of the heavy precipitation type, that developed along the cold front. Cell mergers and training were observed well into the evening hours as the activity quickly spread across southwest Iowa. The storms produced a total of 8 confirmed tornadoes in the Omaha/Valley warning area which covers eastern Nebraska and southwest Iowa.
42.72008-06-11241°48'N / 96°06'W41°51'N / 96°01'W5.00 Miles440 Yards000K0KHarrison
 Brief Description: EVENT NARRATIVE: This is a continuation of the tornado that initially touched down in Burt county Nebraska, about 4.5 miles west of Little Sioux Iowa. The tornado eventually reached EF3 strength in Monona county when it hit a boyscout camp where 4 fatalities and 48 injuries occurred. The tornado crossed into Harrison county near mile marker 97 on Interstate 29 where a semi-truck was flipped. The tornado snapped power poles northeast of there with an estimated strength of EF2 in Harrison county. The tornado then crossed into Monona county Iowa about 4 miles north of Little Sioux. EPISODE NARRATIVE: A very strong and unseasonably cold upper level low pressure system that was tracking across the northern plains brought a strong low level jet to the region during the early morning hours of June 11th. The warm and unstable air that worked north into the region helped spawn early morning severe thunderstorms across eastern Nebraska and southwest Iowa. Later that day as the upper level system worked into the central Dakotas, a cold front pushed across the region. This helped set off another round of thunderstorms that developed over east central Nebraska by late afternoon. Isolated small supercell thunderstorms initially developed ahead of the cold front over eastern Nebraska, but they were quickly overtaken by a broken line of larger supercell thunderstorms, some of the heavy precipitation type, that developed along the cold front. Cell mergers and training were observed well into the evening hours as the activity quickly spread across southwest Iowa. The storms produced a total of 8 confirmed tornadoes in the Omaha/Valley warning area which covers eastern Nebraska and southwest Iowa.
42.81999-04-08341°09'N / 94°47'W41°15'N / 94°42'W7.50 Miles1000 Yards00186K0Cass
 Brief Description: As mentioned in the narrative above, an intense low pressure formed to the southwest of Iowa. The low tracked northeast and lifted into eastern Nebraska. Ahead of the low, a strong low level jet of around 60 knots continued through the day. A nearly stationary frontal boundary extended east from the low. It lifted into southeast Nebraska during the day, but made little progress into southern Iowa. Lines of thunderstorms formed along the boundary through the day and lifted north rapidly. These storms were elevated in nature and as a result produced most of their severe weather in the form of hail. As the day unfolded, a sharp dry line was clearly evident on the satellite as early as 1600 UTC across Kansas. This line raced east during the day. By afternoon, a speed max had rotated around the upper low to the southwest with wind speeds measured by the Lathrop wind profiler at 100 knots at 500 mb by mid afternoon. Jet stream winds were in excess of 120 knots at the same time. Combined with the dynamic situation mentioned above, considerable moisture convergence took place near the triple point between the warm front and the dry line. Surface dew points pooled into to the mid 60s to even a few 70 degree F. dew point readings over northwest Missouri, southeast Nebraska, and southwest Iowa. Meanwhile, dew points fell into the upper 20s over northeast Kansas and south central Nebraska behind the dry line, with teens over central and south central Kansas. Thunderstorms erupted along the dry line by mid day and advanced east through the afternoon. Low level helicity values topped out between 500 and 600 (m/s)**2 just before the first tornadoes formed. Most of the storms in the warm sector became tornadic quickly. The northern limit of the tornado tracks extended about 10 miles or so north of the warm front. Tracks became intermittent very quickly as soon as the storms crossed the surface warm front due to the layer of very cold air just north of the front. Surface temperatures on the cold side of the front were only in the upper 40s to mid 50s. The entire day was very active. Initially, warm air advection thunderstorms produced hail at many locations of central and northern Iowa. Most of is was just below severe levels however. The activity that developed during the afternoon was a combination of warm air advection and the approach of the dryline. At the beginning of the event, the main weather feature was in the form of hail. There were numerous reports of hail three quarters to one and three quarters inch in diameter. The largest hail fell in Guthrie and Dallas Counties with reports of golf ball size hail. One of the storms in the initial wave of afternoon activity became stronger as it moved into southern Story County. Initially, high winds of 60 MPH or more swept through Sheldahl area of Boone County. Greene County was also affected by high winds from the storms. A tornado dropped out of the storm as it moved into the Slater area and was on the ground for about 2 miles. Initial estimates showed 44 homes and businesses damaged in Story County, one was destroyed with major damage to another. Thirty six homes and four businesses were damaged in the town of Slater. Two people were injured during the passage of the tornado. One of the injuries involved a 70 year old man who was picked up by the tornadoes winds and thrown about 10 feet before he latched on to something. His shoulder was dislocated and he required 6 stitches due to his injuries in his hand. High winds northeast of Slater knocked several cars of a Burlington Northern freight train off the tracks after they were blown more than one quarter mile down the track. It was not possible to determine of the cars were knocked off by the tornado or high winds however. This band of storms continue to race and develop northeast through the afternoon. Damage became more sporadic, however high winds occurred as far northeast as Hardin County, with 70 MPH winds reported near New Providence. Hail reports came in from as far northeast as Grundy and Black Hawk Counties, though it was only three quarters of an inch in diameter. Attention then shifted to the tornadic storms that formed near the dry line. During the afternoon, six more tornadoes touched down in Iowa, several of which were long track tornadoes. The first touched down in Taylor County and tracked through Adams, Cass, and Adair Counties. This tornado had was an F4 intensity tornado in parts of Adair and Adams Counties. Damage was extensive with $1,000,000 damage reported in both Adams and Adair Counties. Entire farmsteads were swept clean by the tornado. At one time this tornado was a mile wide wedge with a damage path nearly two miles wide due to the circulation around the tornado. Eyewitness reports indicated that the tornado split into two distinct tornadoes at times, similar to what occurred with the intense F4 tornado in Adair County of 27 May 1995. One of the farmsteads hit near Nodaway was levelled. Reports indicated that a check was blown from the house nearly 100 miles and was found in the town of Jefferson in Greene County. Other checks and papers were found strewn along the path, stretching from Jefferson all the way back to northwest Taylor County. In Adair County, one account indicated pieces of sheet metal from one farm was lifted and deposited six miles away from the farm. Two people were injured by this tornado, one in Adams County with the other in Adair County. One of the injuries Adair County was serious as a man suffered a broken back when the tornado lifted his semi-tractortrailer truck from the Interstate and threw it into a nearby field. The other injuries from this tornado were minor enough that the people were taken to the hospital, treated, and released. There was one account of a horse being picked up by the tornado. It was lifted into the air and thrown through a stand of pine trees 40 feet high. The horse suffered serious injuries and required significant medical attention do to lacerations. The horse amazingly did survive against all odds, though was said would likely lose sight in one eye. The next tornado touched down in Union County and tracked across Madison and Dallas Counties. This tornado had an F4 strength in Union and decreased to a strong F2 in Madison Counties before intensifying again to near F3 strength as it headed into Dallas County. Damage in Union County was around $2,000,000, and around $350,000 in Madison County. There was one person injured by this tornado in Union County. In an amazing account, the Union County Sheriff reported watching as the tornado lifted the car in front of him 35 feet in the air and throwing it 250 feet. The driver was inside during this time and came out of the situation uninjured. Five coal cars were knocked off the tracks in Union County by the tornado as well. This tornado also had a double structure. From eye witness accounts, which also can be shown on Doppler radar imagery, suggest a small rope like tornado passed through the Twelve Mile Lake area shortly before the passage of the main tornado. The next tornado was a weak tornado which touched down about 4 miles west of downtown Des Moines. The tornado did little damage, but did affect one house and several trees. The tornado was seen by a local television sky camera. A short time later, an F2 tornado touched down in Warren County and tracked into southeast Polk County. The track was over rural areas and damage from it was relatively minor. A more significant F3 tornado tracked from northern Lucas County, and weakened to an F2 as it moved across Warren, part of marion, and into Jasper County. One house was destroyed in Lucas County with the four people inside sustaining minor injuries. Once again, this tornado tracked across mostly rural areas, though it did hit a business and two homes in Jasper County and did $1,000,000 in damage. One person was injured in Jasper County. The last tornado touched down in Davis County at Bloomfield and tracked northeast into Wapello County with a maximum strength of F3. Damage in Davis County was over $500,000 as 64 homes and businesses were damaged in the Bloomfield area. To the northeast, the area of the tornado track was mostly rural and damage was limited to outbuildings for the most part. One farmstead reported severe damage near Floris in Davis County. The house was nearly levelled and several outbuildings were completely destroyed. Parts of the house and outbuildings were found as far as 5 miles away from the farmstead. As the storms moved north, high winds were produced over Story County east of Story City. High winds toppled a tractor semi-trailer truck east of Story City on Interstate 35, injuring the driver. Two cars and a truck were also blown off Interstate 35 in Hamilton County. Four people were injured. Two were taken to the hospital, treated, and released. Two were listed in serious condition, one with a neck fracture, the other with a shoulder fracture. The later incident appeared to be from the rear flank downdraft behind the storm and not the initial gust front. From the preliminary data, 178 homes and business were damaged or destroyed by the tornadic storms as well as countless outbuildings. There were several reports of livestock loss as well. It is truly amazing that there was no loss of life during this event and even more amazing is the fact that the injuries that did occur were all minor. Twenty counties in Iowa experienced serious damage from the storms of the day. Iowa Governor Vilsack declared several counties in Iowa disaster areas. These included Taylor, Union, Adams, and Adair Counties. High winds accompanied the storms as the moved through Appanoose County. A local gas station recorded an 81 MPH wind gust as the storms cut a half mile wide swath of destruction west of Moravia. There were numerous reports of cattle killed by the storms. Some were killed by the tornadoes and flying debris, others by lightning. Reports in Adair County, northwest of Fontanelle indicated about 25 head of cattle were struck by lightning shortly before a tornado moved through that area. As the area of storms that produced the high winds north of Ames in central Iowa moved north, they lost their punch. A few of the storms did remain quite strong however. As the area of thunderstorms moved through Cerro Gordo County, high winds blew down a 60 foot corn crib and did some other damage on a farm near Rockwell.
42.81999-04-08440°53'N / 94°53'W41°09'N / 94°48'W18.00 Miles1000 Yards011.0M0Adams
 Brief Description: As mentioned in the narrative above, an intense low pressure formed to the southwest of Iowa. The low tracked northeast and lifted into eastern Nebraska. Ahead of the low, a strong low level jet of around 60 knots continued through the day. A nearly stationary frontal boundary extended east from the low. It lifted into southeast Nebraska during the day, but made little progress into southern Iowa. Lines of thunderstorms formed along the boundary through the day and lifted north rapidly. These storms were elevated in nature and as a result produced most of their severe weather in the form of hail. As the day unfolded, a sharp dry line was clearly evident on the satellite as early as 1600 UTC across Kansas. This line raced east during the day. By afternoon, a speed max had rotated around the upper low to the southwest with wind speeds measured by the Lathrop wind profiler at 100 knots at 500 mb by mid afternoon. Jet stream winds were in excess of 120 knots at the same time. Combined with the dynamic situation mentioned above, considerable moisture convergence took place near the triple point between the warm front and the dry line. Surface dew points pooled into to the mid 60s to even a few 70 degree F. dew point readings over northwest Missouri, southeast Nebraska, and southwest Iowa. Meanwhile, dew points fell into the upper 20s over northeast Kansas and south central Nebraska behind the dry line, with teens over central and south central Kansas. Thunderstorms erupted along the dry line by mid day and advanced east through the afternoon. Low level helicity values topped out between 500 and 600 (m/s)**2 just before the first tornadoes formed. Most of the storms in the warm sector became tornadic quickly. The northern limit of the tornado tracks extended about 10 miles or so north of the warm front. Tracks became intermittent very quickly as soon as the storms crossed the surface warm front due to the layer of very cold air just north of the front. Surface temperatures on the cold side of the front were only in the upper 40s to mid 50s. The entire day was very active. Initially, warm air advection thunderstorms produced hail at many locations of central and northern Iowa. Most of is was just below severe levels however. The activity that developed during the afternoon was a combination of warm air advection and the approach of the dryline. At the beginning of the event, the main weather feature was in the form of hail. There were numerous reports of hail three quarters to one and three quarters inch in diameter. The largest hail fell in Guthrie and Dallas Counties with reports of golf ball size hail. One of the storms in the initial wave of afternoon activity became stronger as it moved into southern Story County. Initially, high winds of 60 MPH or more swept through Sheldahl area of Boone County. Greene County was also affected by high winds from the storms. A tornado dropped out of the storm as it moved into the Slater area and was on the ground for about 2 miles. Initial estimates showed 44 homes and businesses damaged in Story County, one was destroyed with major damage to another. Thirty six homes and four businesses were damaged in the town of Slater. Two people were injured during the passage of the tornado. One of the injuries involved a 70 year old man who was picked up by the tornadoes winds and thrown about 10 feet before he latched on to something. His shoulder was dislocated and he required 6 stitches due to his injuries in his hand. High winds northeast of Slater knocked several cars of a Burlington Northern freight train off the tracks after they were blown more than one quarter mile down the track. It was not possible to determine of the cars were knocked off by the tornado or high winds however. This band of storms continue to race and develop northeast through the afternoon. Damage became more sporadic, however high winds occurred as far northeast as Hardin County, with 70 MPH winds reported near New Providence. Hail reports came in from as far northeast as Grundy and Black Hawk Counties, though it was only three quarters of an inch in diameter. Attention then shifted to the tornadic storms that formed near the dry line. During the afternoon, six more tornadoes touched down in Iowa, several of which were long track tornadoes. The first touched down in Taylor County and tracked through Adams, Cass, and Adair Counties. This tornado had was an F4 intensity tornado in parts of Adair and Adams Counties. Damage was extensive with $1,000,000 damage reported in both Adams and Adair Counties. Entire farmsteads were swept clean by the tornado. At one time this tornado was a mile wide wedge with a damage path nearly two miles wide due to the circulation around the tornado. Eyewitness reports indicated that the tornado split into two distinct tornadoes at times, similar to what occurred with the intense F4 tornado in Adair County of 27 May 1995. One of the farmsteads hit near Nodaway was levelled. Reports indicated that a check was blown from the house nearly 100 miles and was found in the town of Jefferson in Greene County. Other checks and papers were found strewn along the path, stretching from Jefferson all the way back to northwest Taylor County. In Adair County, one account indicated pieces of sheet metal from one farm was lifted and deposited six miles away from the farm. Two people were injured by this tornado, one in Adams County with the other in Adair County. One of the injuries Adair County was serious as a man suffered a broken back when the tornado lifted his semi-tractortrailer truck from the Interstate and threw it into a nearby field. The other injuries from this tornado were minor enough that the people were taken to the hospital, treated, and released. There was one account of a horse being picked up by the tornado. It was lifted into the air and thrown through a stand of pine trees 40 feet high. The horse suffered serious injuries and required significant medical attention do to lacerations. The horse amazingly did survive against all odds, though was said would likely lose sight in one eye. The next tornado touched down in Union County and tracked across Madison and Dallas Counties. This tornado had an F4 strength in Union and decreased to a strong F2 in Madison Counties before intensifying again to near F3 strength as it headed into Dallas County. Damage in Union County was around $2,000,000, and around $350,000 in Madison County. There was one person injured by this tornado in Union County. In an amazing account, the Union County Sheriff reported watching as the tornado lifted the car in front of him 35 feet in the air and throwing it 250 feet. The driver was inside during this time and came out of the situation uninjured. Five coal cars were knocked off the tracks in Union County by the tornado as well. This tornado also had a double structure. From eye witness accounts, which also can be shown on Doppler radar imagery, suggest a small rope like tornado passed through the Twelve Mile Lake area shortly before the passage of the main tornado. The next tornado was a weak tornado which touched down about 4 miles west of downtown Des Moines. The tornado did little damage, but did affect one house and several trees. The tornado was seen by a local television sky camera. A short time later, an F2 tornado touched down in Warren County and tracked into southeast Polk County. The track was over rural areas and damage from it was relatively minor. A more significant F3 tornado tracked from northern Lucas County, and weakened to an F2 as it moved across Warren, part of marion, and into Jasper County. One house was destroyed in Lucas County with the four people inside sustaining minor injuries. Once again, this tornado tracked across mostly rural areas, though it did hit a business and two homes in Jasper County and did $1,000,000 in damage. One person was injured in Jasper County. The last tornado touched down in Davis County at Bloomfield and tracked northeast into Wapello County with a maximum strength of F3. Damage in Davis County was over $500,000 as 64 homes and businesses were damaged in the Bloomfield area. To the northeast, the area of the tornado track was mostly rural and damage was limited to outbuildings for the most part. One farmstead reported severe damage near Floris in Davis County. The house was nearly levelled and several outbuildings were completely destroyed. Parts of the house and outbuildings were found as far as 5 miles away from the farmstead. As the storms moved north, high winds were produced over Story County east of Story City. High winds toppled a tractor semi-trailer truck east of Story City on Interstate 35, injuring the driver. Two cars and a truck were also blown off Interstate 35 in Hamilton County. Four people were injured. Two were taken to the hospital, treated, and released. Two were listed in serious condition, one with a neck fracture, the other with a shoulder fracture. The later incident appeared to be from the rear flank downdraft behind the storm and not the initial gust front. From the preliminary data, 178 homes and business were damaged or destroyed by the tornadic storms as well as countless outbuildings. There were several reports of livestock loss as well. It is truly amazing that there was no loss of life during this event and even more amazing is the fact that the injuries that did occur were all minor. Twenty counties in Iowa experienced serious damage from the storms of the day. Iowa Governor Vilsack declared several counties in Iowa disaster areas. These included Taylor, Union, Adams, and Adair Counties. High winds accompanied the storms as the moved through Appanoose County. A local gas station recorded an 81 MPH wind gust as the storms cut a half mile wide swath of destruction west of Moravia. There were numerous reports of cattle killed by the storms. Some were killed by the tornadoes and flying debris, others by lightning. Reports in Adair County, northwest of Fontanelle indicated about 25 head of cattle were struck by lightning shortly before a tornado moved through that area. As the area of storms that produced the high winds north of Ames in central Iowa moved north, they lost their punch. A few of the storms did remain quite strong however. As the area of thunderstorms moved through Cerro Gordo County, high winds blew down a 60 foot corn crib and did some other damage on a farm near Rockwell.
42.91984-06-12240°48'N / 96°09'W40°55'N / 95°59'W11.00 Miles100 Yards002.5M0Cass
43.21964-06-22440°42'N / 95°27'W40°46'N / 95°14'W11.90 Miles400 Yards00250K0Fremont
43.31959-05-04241°42'N / 94°55'W41°45'N / 94°51'W4.10 Miles100 Yards003K0Audubon
43.31968-04-16240°43'N / 95°27'W2.00 Miles200 Yards0025K0Fremont
44.31959-05-26240°36'N / 95°38'W40°49'N / 95°45'W15.90 Miles400 Yards0025K0Fremont
44.41953-06-27541°27'N / 94°42'W12250K0Adair
45.21952-08-13441°01'N / 96°19'W40°56'N / 96°13'W7.30 Miles33 Yards00250K0Cass
45.21991-05-28241°56'N / 95°57'W41°56'N / 95°53'W5.00 Miles60 Yards00250K0Monona
45.31964-04-12440°40'N / 95°14'W40°50'N / 95°06'W13.10 Miles400 Yards1282.5M0Page
45.51960-06-15241°42'N / 96°17'W0025K0Burt
46.41999-04-08240°51'N / 94°54'W40°54'N / 94°54'W3.00 Miles500 Yards00500K0Taylor
 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.
46.61968-04-16240°40'N / 95°30'W0.50 Mile33 Yards003K0Fremont
46.61964-09-22240°39'N / 95°14'W40°48'N / 95°07'W11.80 Miles300 Yards00250K0Page
46.71983-05-01240°38'N / 95°40'W40°42'N / 95°35'W7.00 Miles20 Yards032.5M0Fremont
47.01988-05-07241°07'N / 96°28'W41°07'N / 96°20'W7.00 Miles73 Yards002.5M0Saunders
47.12004-08-26240°39'N / 95°36'W40°40'N / 95°33'W3.00 Miles880 Yards0000Fremont
 Brief Description: A tornado that eventually reached f2 in strength first touched down 2.5 miles southwest of Riverton. The tornado reached it's maximum intensity and maximum damage width of 1/2 mile when it destroyed a home on 270th street. The tornado also caused signifcant damage to another house, several vehicles, other farm outbuildings, crops and trees before lifting 1 mile southeast of Riverton.
47.61984-06-07340°50'N / 94°57'W40°53'N / 94°50'W7.00 Miles100 Yards002.5M0Taylor
48.01984-06-07340°44'N / 95°02'W40°50'N / 94°57'W7.00 Miles100 Yards032.5M0Page
48.61984-06-07340°53'N / 94°50'W40°59'N / 94°44'W11.00 Miles100 Yards002.5M0Adams
48.81964-06-19340°44'N / 95°03'W40°50'N / 94°53'W10.60 Miles200 Yards01250K0Page
48.91959-05-18240°59'N / 94°44'W1.00 Mile200 Yards00250K0Adams
49.31975-06-18240°40'N / 95°14'W0025K0Page
49.51952-08-13441°13'N / 96°35'W41°01'N / 96°19'W19.40 Miles110 Yards020250K0Saunders


* 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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