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Roseville, IA Natural Disasters and Weather Extremes

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

Roseville, 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

Roseville, 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, #265

Roseville, IA
258.01
Iowa
236.74
U.S.
136.45

The tornado index value is calculated based on historical tornado events data using USA.com algorithms. It is an indicator of the tornado level in a region. A higher tornado index value means a higher chance of tornado events.

Other Weather Extremes Events

A total of 3,497 other weather extremes events within 50 miles of Roseville, IA were recorded from 1950 to 2010. The following is a break down of these events:

TypeCountTypeCountTypeCountTypeCountTypeCount
Avalanche:0Blizzard:33Cold:29Dense Fog:4Drought:9
Dust Storm:0Flood:420Hail:1,280Heat:9Heavy Snow:40
High Surf:0Hurricane:0Ice Storm:19Landslide:0Strong Wind:66
Thunderstorm Winds:1,273Tropical Storm:0Wildfire:0Winter Storm:68Winter Weather:31
Other:216 

Volcanos Nearby

No volcano is found in or near Roseville, IA.

Historical Earthquake Events

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

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

Historical Tornado Events

A total of 101 historical tornado events that had recorded magnitude of 2 or above found in or near Roseville, IA.

Distance (miles)DateMagnitudeStart Lat/LogEnd Lat/LogLengthWidthFatalitiesInjuriesProperty DamageCrop DamageAffected County
4.71968-05-15542°54'N / 92°53'W43°10'N / 92°33'W24.70 Miles600 Yards1345025.0M0Floyd
7.51964-08-27243°06'N / 92°42'W1.00 Mile77 Yards0025K0Floyd
7.71970-09-09242°54'N / 92°48'W42°56'N / 92°45'W1.90 Miles200 Yards0025K0Butler
10.11971-06-06242°52'N / 92°47'W42°54'N / 92°44'W1.30 Miles200 Yards01250K0Greene
11.21953-05-20342°33'N / 93°03'W43°12'N / 92°24'W55.60 Miles400 Yards000K0Hardin
12.91986-09-28243°09'N / 92°37'W0.20 Mile23 Yards02250K0Floyd
13.01975-06-04242°51'N / 92°43'W0025K0Butler
13.91961-09-01442°47'N / 93°00'W42°52'N / 92°33'W23.30 Miles27 Yards072.5M0Butler
16.41968-05-15542°46'N / 93°07'W42°54'N / 92°53'W14.70 Miles600 Yards000K0Franklin
17.81954-05-23243°17'N / 92°48'W000K0Mitchell
18.11981-05-23243°16'N / 92°55'W43°18'N / 92°50'W3.80 Miles50 Yards00250K0Mitchell
18.41961-09-01442°52'N / 92°33'W42°53'N / 92°28'W3.30 Miles27 Yards002.5M0Bremer
18.61968-05-15543°10'N / 92°33'W43°13'N / 92°29'W4.10 Miles600 Yards000K0Chickasaw
18.71970-09-09242°51'N / 92°32'W42°53'N / 92°29'W2.30 Miles150 Yards0025K0Bremer
20.21998-06-27242°59'N / 93°20'W43°04'N / 93°05'W12.50 Miles50 Yards00125K10KCerro Gordo
 Brief Description: Iowa was located in the warm sector of a developing storm system to the west. The warm front had moved to the northern Iowa border during the afternoon of the 27th with dew point temperatures in the mid 70s to around 80 blanketing the state in the warm sector. Initially, the airmass was capped, preventing thunderstorms from forming during the afternoon. Slightly cooler air moved in during the evening hours. In addition to the slightly cooler air moving in aloft, a cold front was poised over eastern Nebraska ready to move east into the state. Thunderstorms erupted rapidly by early evening with hail and high winds reported over northern Iowa. There were numerous reports of hail of an inch or larger in diameter, with a few reports of golf ball size hail. High winds were also a problem with many of the storms producing 60 to 70 MPH wind gusts. Reports of tree and power line damage were widespread. There were a few tornadoes as well. One tracked across open country in Cerro Gordo County before damaging a house south of Clear Lake. Another tornado touched down near Swaledale in Cerro Gordo County and passed southeast of Mason City. Much of the track was over open country, however one house was destroyed near Swaledale by this tornado. The longest track tornado moved across Butler and Bremer Counties. It also passed through open country, causing damage to crops and out buildings. In addition to these, there were a few brief touchdowns reported. Iowa soil remained very saturated with numerous rivers at or near flood stage. Heavy rainfall of near 4 inches in a couple hours time caused flash flooding in Cerro Gordo County. A widespread area of north central into northeast Iowa received heavy rainfall. Many areas picked up two to four inches of rain in a few hour period. This resulted in urban and small stream flooding, and ultimately general river flooding in the days that followed. As the storms moved through Worth County, lightning struck an outbuilding west of Kensett. The building was set on fire and destroyed.
20.61952-05-23242°45'N / 92°58'W000K0Butler
21.21993-08-09243°04'N / 92°27'W43°04'N / 92°20'W5.00 Miles55 Yards02500K50KChickasaw
21.41965-05-05443°17'N / 92°49'W43°23'N / 92°43'W8.20 Miles150 Yards0625K0Floyd
21.91994-07-07242°58'N / 92°29'W43°04'N / 92°16'W9.50 Miles100 Yards00500K5KChickasaw
22.61980-05-29243°11'N / 93°12'W0.50 Mile30 Yards0025K0Cerro Gordo
23.61977-07-16242°48'N / 92°29'W42°48'N / 92°26'W1.90 Miles20 Yards00250K0Bremer
24.11971-07-12443°14'N / 92°27'W43°13'N / 92°23'W2.30 Miles1320 Yards042.5M0Howard
25.11966-06-11243°23'N / 92°54'W1.00 Mile250 Yards0025K0Mitchell
25.32001-09-06242°42'N / 92°34'W42°47'N / 92°25'W10.00 Miles100 Yards00100K10KBremer
 Brief Description: Tornado moved in from Butler County and touched down again, mostly in open field. A car and garage was damaged in Bremer County. A strong upper level low pressure lifted northeast out of the southern Plains during the afternoon of the 6th. During the heating of the afternoon, thunderstorms erupted in the unstable air. The freezing level was around 15,000 feet, so hail was not a great threat. Surface dew point temperatures were in the upper 60s to low 70s with precipitable water values around 1.75 inches. Thunderstorms fired southwest of the Des Moines metropolitan area. A tornado touched down in rural Madison County. The tornado was about 60 feet wide and produced a half mile long path of damage in open country. As the storms moved northeast they continued to intensity. One cell dropped a tornado at the Glen Oaks Golf Course in West Des Moines, causing some minor damage there. The tornado tracked northeast and flipped a semi tractor-trailer truck in Interstate 35 resulting in one injury. It continued northeast and hit an apartment complex causing damage to the building and destroying an 8-car garage. The path was more intermittent as it continued northeast into the city. There were numerous reports of trees and power lines being downed. The tornado lifted as the event transitioned into a high wind event. The storms produced wind damage in Johnston as it moved through the area. High winds of 80 to 85 MPH occurred in northern Polk and southern Story Counties before they weakened. A grain bin was flattened, along with tree and crop damage, as the storm moved through the Elkhart area. Just northwest of that, in Slater, high winds took the roof off of a house in southern Story County. One person in the house was injured. The storms continued to track northeast, eventually dropping another tornado in Butler and Bremer Counties. The tornado had a somewhat intermittent track touching down south of Shell Rock and lifting northeast of Waverly. For the most part the tornado tracked through corn fields there. One farmstead was hit in Butler County. A grain bin was destroyed and blown one quarter of a mile across a field, another was blown off its foundation, a shed was destroyed, and crops were damaged. In Bremer County, one car and a garage were damaged along the tornadoes path. Another farmstead was hit north of Waverly. Part of a machine garage was destroyed and blown about 30 feet off of its foundation.
26.21965-05-05443°23'N / 92°43'W43°23'N / 92°33'W7.90 Miles150 Yards0025K0Floyd
26.41971-07-12343°20'N / 93°02'W43°28'N / 92°47'W15.40 Miles833 Yards002.5M0Worth
26.91967-04-30443°18'N / 93°10'W43°26'N / 92°58'W13.30 Miles400 Yards00250K0Worth
27.31998-06-27242°35'N / 92°56'W42°41'N / 92°32'W20.50 Miles75 Yards0010K2KButler
 Brief Description: Iowa was located in the warm sector of a developing storm system to the west. The warm front had moved to the northern Iowa border during the afternoon of the 27th with dew point temperatures in the mid 70s to around 80 blanketing the state in the warm sector. Initially, the airmass was capped, preventing thunderstorms from forming during the afternoon. Slightly cooler air moved in during the evening hours. In addition to the slightly cooler air moving in aloft, a cold front was poised over eastern Nebraska ready to move east into the state. Thunderstorms erupted rapidly by early evening with hail and high winds reported over northern Iowa. There were numerous reports of hail of an inch or larger in diameter, with a few reports of golf ball size hail. High winds were also a problem with many of the storms producing 60 to 70 MPH wind gusts. Reports of tree and power line damage were widespread. There were a few tornadoes as well. One tracked across open country in Cerro Gordo County before damaging a house south of Clear Lake. Another tornado touched down near Swaledale in Cerro Gordo County and passed southeast of Mason City. Much of the track was over open country, however one house was destroyed near Swaledale by this tornado. The longest track tornado moved across Butler and Bremer Counties. It also passed through open country, causing damage to crops and out buildings. In addition to these, there were a few brief touchdowns reported. Iowa soil remained very saturated with numerous rivers at or near flood stage. Heavy rainfall of near 4 inches in a couple hours time caused flash flooding in Cerro Gordo County. A widespread area of north central into northeast Iowa received heavy rainfall. Many areas picked up two to four inches of rain in a few hour period. This resulted in urban and small stream flooding, and ultimately general river flooding in the days that followed. As the storms moved through Worth County, lightning struck an outbuilding west of Kensett. The building was set on fire and destroyed.
27.61998-06-27242°40'N / 92°34'W42°42'N / 92°29'W5.00 Miles75 Yards003K1KBremer
 Brief Description: Iowa was located in the warm sector of a developing storm system to the west. The warm front had moved to the northern Iowa border during the afternoon of the 27th with dew point temperatures in the mid 70s to around 80 blanketing the state in the warm sector. Initially, the airmass was capped, preventing thunderstorms from forming during the afternoon. Slightly cooler air moved in during the evening hours. In addition to the slightly cooler air moving in aloft, a cold front was poised over eastern Nebraska ready to move east into the state. Thunderstorms erupted rapidly by early evening with hail and high winds reported over northern Iowa. There were numerous reports of hail of an inch or larger in diameter, with a few reports of golf ball size hail. High winds were also a problem with many of the storms producing 60 to 70 MPH wind gusts. Reports of tree and power line damage were widespread. There were a few tornadoes as well. One tracked across open country in Cerro Gordo County before damaging a house south of Clear Lake. Another tornado touched down near Swaledale in Cerro Gordo County and passed southeast of Mason City. Much of the track was over open country, however one house was destroyed near Swaledale by this tornado. The longest track tornado moved across Butler and Bremer Counties. It also passed through open country, causing damage to crops and out buildings. In addition to these, there were a few brief touchdowns reported. Iowa soil remained very saturated with numerous rivers at or near flood stage. Heavy rainfall of near 4 inches in a couple hours time caused flash flooding in Cerro Gordo County. A widespread area of north central into northeast Iowa received heavy rainfall. Many areas picked up two to four inches of rain in a few hour period. This resulted in urban and small stream flooding, and ultimately general river flooding in the days that followed. As the storms moved through Worth County, lightning struck an outbuilding west of Kensett. The building was set on fire and destroyed.
28.51994-07-19243°15'N / 92°26'W43°16'N / 92°15'W8.50 Miles40 Yards0050K5KHoward
28.61956-07-17243°04'N / 92°16'W43°02'N / 92°13'W2.30 Miles200 Yards010K0Chickasaw
28.91967-04-30343°06'N / 93°25'W43°11'N / 93°18'W7.70 Miles250 Yards00250K0Cerro Gordo
29.01974-05-28343°20'N / 93°13'W43°22'N / 93°08'W3.80 Miles150 Yards032.5M0Worth
29.31959-05-10242°45'N / 93°20'W42°49'N / 93°14'W6.50 Miles300 Yards0025K0Franklin
29.71968-05-15543°13'N / 92°29'W43°28'N / 92°20'W18.60 Miles600 Yards0123K0Howard
30.21971-07-12443°13'N / 92°23'W43°05'N / 92°05'W17.50 Miles1320 Yards002.5M0Chickasaw
30.31953-05-20343°12'N / 92°24'W43°26'N / 92°19'W16.50 Miles400 Yards000K0Chickasaw
30.31998-06-27242°59'N / 93°26'W43°04'N / 93°23'W7.50 Miles50 Yards0050K2KCerro Gordo
 Brief Description: Iowa was located in the warm sector of a developing storm system to the west. The warm front had moved to the northern Iowa border during the afternoon of the 27th with dew point temperatures in the mid 70s to around 80 blanketing the state in the warm sector. Initially, the airmass was capped, preventing thunderstorms from forming during the afternoon. Slightly cooler air moved in during the evening hours. In addition to the slightly cooler air moving in aloft, a cold front was poised over eastern Nebraska ready to move east into the state. Thunderstorms erupted rapidly by early evening with hail and high winds reported over northern Iowa. There were numerous reports of hail of an inch or larger in diameter, with a few reports of golf ball size hail. High winds were also a problem with many of the storms producing 60 to 70 MPH wind gusts. Reports of tree and power line damage were widespread. There were a few tornadoes as well. One tracked across open country in Cerro Gordo County before damaging a house south of Clear Lake. Another tornado touched down near Swaledale in Cerro Gordo County and passed southeast of Mason City. Much of the track was over open country, however one house was destroyed near Swaledale by this tornado. The longest track tornado moved across Butler and Bremer Counties. It also passed through open country, causing damage to crops and out buildings. In addition to these, there were a few brief touchdowns reported. Iowa soil remained very saturated with numerous rivers at or near flood stage. Heavy rainfall of near 4 inches in a couple hours time caused flash flooding in Cerro Gordo County. A widespread area of north central into northeast Iowa received heavy rainfall. Many areas picked up two to four inches of rain in a few hour period. This resulted in urban and small stream flooding, and ultimately general river flooding in the days that followed. As the storms moved through Worth County, lightning struck an outbuilding west of Kensett. The building was set on fire and destroyed.
32.31999-07-02242°34'N / 92°53'W42°33'N / 92°47'W4.50 Miles35 Yards0025K1KButler
 Brief Description: A very active weather pattern was in place over the central U.S. A strong west-northwest wind flow was in place over the state. Meanwhile a warm front was lifting north from the southern Plains. The warm front separated the cooler and dry air to the north from very humid air to the south. Dew point temperatures in the air to the south of the front were in the mid 70s to low 80s. Precipitable water values were near 2 inches as well. A meso scale convective system formed over north central Nebraska and south central South Dakota during the previous night. The remains of this system drifted into west central Iowa during the predawn hours. One cell became severe during the morning. This was to be the pattern for much of the rest of the day as the cells that formed became super cellular, with each supercell lasting about 2 hours. By the early afternoon hours, surface based CAPE values were approaching 6000 J/kg just to the south of the thunderstorm genesis region. Once the storms formed they became supercells quickly. Very strong sheer was in place with strong southeast surface winds veering to westerly winds in the mid levels. Even though freezing levels were in excess of 15,000 feet, the storms were prolific hail producers. WSR-88D VIL values with many of the supercells exceeded 90 kg/m/m. There was also some high winds with the storms at times as many of the cells were rotating as was seen with WSR-88D imagery. The first high winds occurred early in the severe event as 64 MPH winds blasted into the Dow City area of Crawford County. Winds of 66 MPH were recorded at the Denison Municipal Airport as the storm moved through. Damage was reported in many areas of the county. During the day there were also other spotty reports of wind damage, however most of the were were in the 40 to 50 MPH range. A few other cells did produce severe criteria winds as they moved into the central and northeast counties of the state with wind damage reported in Hardin, Hamilton, and Boone Counties. These storms developed during the period of time the weather system was changing from a supercell type system into more of a multi-cell system. The main severe weather event of the day was the hail. Hail reports of one inch up to golf ball size were too numerous to mention. Some of the hail was larger than tennis balls. Baseball size hail fell in Guthrie County, into Adair and Dallas Counties as one of the cells advanced east-southeast. The largest hail actually fell east of Casey in Guthrie County. Softball size hail fell there, smashing windshields on numerous cars. Needless to say, crop damage was widespread from west central into central Iowa along the paths of the two to three supercells that moved through the area. Scattered crop damage occurred with the multi-cellular storms over central into northeast Iowa as well. An example of the damage caused by the hail came by way of a report from Crawford County. Reports indicated hail damaged 80,000 to 100,000 acres of crops with widespread damage. Roads and ditches sustained between $150,000 and $200,000 in damage. Tree removal in the county was #30,000, with $100,000 damage to homes and businesses in the county. By the early evening, the weather system had made a transition from severe weather to heavy rain. Intense rainfall occurred over northeast Iowa. Flash flooding was widespread over northern Grundy, southern Butler, southern Bremer, and most of Black Hawk Counties. A large swath of 6 to 8 inch rainfall occurred over the Beaver Creek basin, causing flash flooding in the area and an eventual flood of near record proportions. County officials reported the flooding as very serious with countless roads and highways under water. Cars were stranded and thousands of basements were flooded by the onslaught of heavy rain. One report indicated several head of cattle lost as they were drown by the flood waters in Grundy County. No doubt, this was not the only case of livestock loss due to the flooding. Another report from the Dewar area, east of Waterloo, indicated about a block of railroad was washed out. Damage there was reported to 33 houses, a car repair shop, and a tavern. Rainfall was in excess of three inches per hour in many areas. The heaviest rainfall officially was around 9 inches. Some unofficial reports in the Cedar Falls area included up to 9 inches of rainfall in a 90 minute period. The observer at Parkersburg picked up 6.55 inches of rain in under 3 hours. A bucket survey in the area showed rainfall of 11 to 14 inches at a few locations in Butler County. The heavy rain occurred as a series of storms formed and trained over the same areas. The complex of thunderstorms that developed was a back developing complex. Late in the life of the system, one of the storms became severe. This storm displayed a meso circulation on the WSR-88D in Johnston, IA, though it was not all that well formed. The storm was the last in the series of storms and layed down a path of damage. The swath was about 13 miles long, extending across southern Butler and northern Grundy Counties. The damage path looked to be more downburst in nature, though there were reports of a tornado imbedded in the flow pattern. The situation was not all that different from the meso cyclone/tornado system that moved through Boone, Dallas, and Polk Counties about a year earlier on 29 June 1998. The tornado caused damage to several farmsteads along the road. The worst hit was on farmstead where all of the farm buildings were destroyed and only the superstructure of the farmhouse remained. Debris was wrapped up in trees for many miles along the path. One other tornado did occur earlier in the day. The tornado came from one of the supercells over western Iowa. A relatively small tornado touched down in Audubon County west of Hamlin. There was little damage reported with this tornado.
32.51971-05-31242°33'N / 93°02'W42°36'N / 92°57'W4.50 Miles300 Yards00250K0Hardin
32.72008-05-25542°33'N / 92°51'W42°34'N / 92°33'W16.00 Miles1235 Yards95075.0M75KButler
 Brief Description: EVENT NARRATIVE: First EF5 tornado in Iowa since 13 June 1976. Nine deaths and 50 injuries occurred in Butler County. Tornado moved out of Butler County and continued in Black Hawk County. EPISODE NARRATIVE: A very intense upper low was located over the southwest U.S. and lifted northeast during the weekend of the 24th into the morning of the 26th. The seasons first strong push of deep moisture moved into Iowa on the 25th with surface temperatures warming into the mid 80s and dew points surging into the upper 60s to low 70s. Precipitable water values were near 1.5 inches. The dry slot pushed north across the area the previous night as the warm front lifted north. The primary surface low was located over northern Minnesota. A cold front extended south from the low into northwest Iowa. The airmass became very unstable by the mid afternoon hours. MUCAPE rose to between 4000 and 5000 J/kg. Lifted indices fell to -8 to -11 C. There was a considerable amount of both DCAPE at 1000-1500 J/kg and cape in the -10 to-30 C. layer of the atmoshpere, between 400 and 600 J/kg. The freezing level was around 13,200 feet. The environment was quite sheared with effective shear in the 40 to 50 kt range. LCL values were between 1000 and 1500 meters. The airmass was initially capped. During the late afternoon hours, a small cluster of thunderstorms formed over north central into northeast Iowa. The storms became severe very quickly. Initially, the storms dropped hail up to golf ball in size. One became a strong super cell and produced a major tornado. This cell, in addition to being tornadic, also produced hail of baseball to softball in size and winds in excess of 90 MPH. The tornado track was from approximately 2 miles south of Aplington to Parkersburg, then continued to New Hartford and across northern Black Hawk County. The average path width ranged from 0.6 to 0.7 miles near Parkersburg to just north of New Hartford. The path constricted to near one quarter mile wide east of New Hartford to north of Waterloo. The width then increased to near 1.2 miles wide north of Dunkerton before dissipating near the Black Hawk and Buchanan County line. The tornado was on the ground for approximately 43 miles. In addition to the main tornado, a satellite tornado was observed by storm chasers and one off duty NWS employee. It was located south of the main tornado and was on the ground for a little over a mile in Grundy County. Initial reports indicated 9 fatalities with 7 in Parkersburg (pop 1889) and 2 in New Hartford (pop 637). There were at least 50 injuries, with 4 of those in critical condition. Two of the fatalities occurred a few days after the tornado from injuries sustained in the tornado. The last fatality occurred on 7 Nov. A 61 year old female sustained injuries in the stairwell of her home when a 2 x 4 was thrown through her right side lung. She was hospitalized and died several months later of complications. Significant structural damage occurred across the southern end of Parkersburg and along a path to just north of New Hartford. Numerous structures completely destroyed from Parkersburg to near New Hartford. The tornado continued eastward to just north of the Waterloo and Cedar Falls area. Significant damage also occurred north of Dunkerton where the tornado increased to its greatest path width. This storm also produced substantial straight line wind damage along the southern periphery of the storm just south of the tornado track. News accounts indicated that a receipt from Parkersburg was found around 1915 CST 3 miles north of Prairie du Chien, WI, 109 miles to the northeast. Receipits were also found in Clayton County at Elkader, and full scrapbook pages and photos were found in far northeast Bremer County at Sumner. Preliminary estimates that straight line winds of 90 to 100 MPH occurred with this storm. At 1637 CST, the Waterloo Airport recorded a 93 MPH wind gust. Survey results suggest that straight line wind damage was the cause of the severe damage at the recreational vehicle dealership north of Cedar Falls. At least 627 homes were damaged, including 288 homes destroyed in Parkersburg, 88 in New Hartford, 15 in Hazelton and another 50 in Black Hawk County. In addition, 58 had major damage, 33 had moderate damage, 2 were inaccessible, and 93 damaged but able to be occupied. There were also 21 businesses destroyed. Governor Chet Culver declared both Butler and Black Hawk disaster areas with both given the State Declaration. A Federal Disaster Declaration occurred two days later for both Butler and Black Hawk Counties. The tornado was rated a low end EF5 by a Quick Response Team (QRT) in portions of Parkersburg and north of New Hartford with peak winds estimated at 205 MPH. For historical reference, the last F5 tornado to hit Iowa was on 13 June 1976 in Boone and Story Counties in the town of Jordan, with a 21 mile path length. The last F4 tornado to hit Iowa was in Union, Madison, and Dallas Counties with a 56 mile path length on 8 April 1999. There was one other smaller tornado during the evening. A tornado touched down in Clarke County and was on the ground for a short time southeast of Osceola. After the initial thunderstorm area developed over north central and northeast Iowa, a large complex developed over southeast Nebraska. The two areas of storms filled in to form a squall line by the mid evening hours. The complex over Nebraska then pushed east and northeast along the squall line. A considerable amount of severe weather was generated during the evening as this occurred. Along the squall line, high winds and hail were common with the dominant mode of severe weather being hail of up to golf ball in size. As the MCS out of Nebraska advanced east, a tail extending south from the centroid took on a bow echo configuration and raced east across Iowa at 65 MPH. Very high winds occurred with this feature with numerous locations reporting winds of 65 to 85 MPH. Some of the higher winds included an 85 MPH wind gust in the Winterset area and numerous reports of 75 to 85 MPH winds from Madison, Dallas, Warren and Polk Counties. Lightning struck a house in Ankeny. The house was set on fire by the strike.
32.92008-05-25242°33'N / 92°52'W42°33'N / 92°51'W1.00 Mile75 Yards00300K2KGrundy
 Brief Description: EVENT NARRATIVE: This was the initial tornado touchdown point. The tornado continued on into Butler County. EPISODE NARRATIVE: A very intense upper low was located over the southwest U.S. and lifted northeast during the weekend of the 24th into the morning of the 26th. The seasons first strong push of deep moisture moved into Iowa on the 25th with surface temperatures warming into the mid 80s and dew points surging into the upper 60s to low 70s. Precipitable water values were near 1.5 inches. The dry slot pushed north across the area the previous night as the warm front lifted north. The primary surface low was located over northern Minnesota. A cold front extended south from the low into northwest Iowa. The airmass became very unstable by the mid afternoon hours. MUCAPE rose to between 4000 and 5000 J/kg. Lifted indices fell to -8 to -11 C. There was a considerable amount of both DCAPE at 1000-1500 J/kg and cape in the -10 to-30 C. layer of the atmoshpere, between 400 and 600 J/kg. The freezing level was around 13,200 feet. The environment was quite sheared with effective shear in the 40 to 50 kt range. LCL values were between 1000 and 1500 meters. The airmass was initially capped. During the late afternoon hours, a small cluster of thunderstorms formed over north central into northeast Iowa. The storms became severe very quickly. Initially, the storms dropped hail up to golf ball in size. One became a strong super cell and produced a major tornado. This cell, in addition to being tornadic, also produced hail of baseball to softball in size and winds in excess of 90 MPH. The tornado track was from approximately 2 miles south of Aplington to Parkersburg, then continued to New Hartford and across northern Black Hawk County. The average path width ranged from 0.6 to 0.7 miles near Parkersburg to just north of New Hartford. The path constricted to near one quarter mile wide east of New Hartford to north of Waterloo. The width then increased to near 1.2 miles wide north of Dunkerton before dissipating near the Black Hawk and Buchanan County line. The tornado was on the ground for approximately 43 miles. In addition to the main tornado, a satellite tornado was observed by storm chasers and one off duty NWS employee. It was located south of the main tornado and was on the ground for a little over a mile in Grundy County. Initial reports indicated 9 fatalities with 7 in Parkersburg (pop 1889) and 2 in New Hartford (pop 637). There were at least 50 injuries, with 4 of those in critical condition. Two of the fatalities occurred a few days after the tornado from injuries sustained in the tornado. The last fatality occurred on 7 Nov. A 61 year old female sustained injuries in the stairwell of her home when a 2 x 4 was thrown through her right side lung. She was hospitalized and died several months later of complications. Significant structural damage occurred across the southern end of Parkersburg and along a path to just north of New Hartford. Numerous structures completely destroyed from Parkersburg to near New Hartford. The tornado continued eastward to just north of the Waterloo and Cedar Falls area. Significant damage also occurred north of Dunkerton where the tornado increased to its greatest path width. This storm also produced substantial straight line wind damage along the southern periphery of the storm just south of the tornado track. News accounts indicated that a receipt from Parkersburg was found around 1915 CST 3 miles north of Prairie du Chien, WI, 109 miles to the northeast. Receipits were also found in Clayton County at Elkader, and full scrapbook pages and photos were found in far northeast Bremer County at Sumner. Preliminary estimates that straight line winds of 90 to 100 MPH occurred with this storm. At 1637 CST, the Waterloo Airport recorded a 93 MPH wind gust. Survey results suggest that straight line wind damage was the cause of the severe damage at the recreational vehicle dealership north of Cedar Falls. At least 627 homes were damaged, including 288 homes destroyed in Parkersburg, 88 in New Hartford, 15 in Hazelton and another 50 in Black Hawk County. In addition, 58 had major damage, 33 had moderate damage, 2 were inaccessible, and 93 damaged but able to be occupied. There were also 21 businesses destroyed. Governor Chet Culver declared both Butler and Black Hawk disaster areas with both given the State Declaration. A Federal Disaster Declaration occurred two days later for both Butler and Black Hawk Counties. The tornado was rated a low end EF5 by a Quick Response Team (QRT) in portions of Parkersburg and north of New Hartford with peak winds estimated at 205 MPH. For historical reference, the last F5 tornado to hit Iowa was on 13 June 1976 in Boone and Story Counties in the town of Jordan, with a 21 mile path length. The last F4 tornado to hit Iowa was in Union, Madison, and Dallas Counties with a 56 mile path length on 8 April 1999. There was one other smaller tornado during the evening. A tornado touched down in Clarke County and was on the ground for a short time southeast of Osceola. After the initial thunderstorm area developed over north central and northeast Iowa, a large complex developed over southeast Nebraska. The two areas of storms filled in to form a squall line by the mid evening hours. The complex over Nebraska then pushed east and northeast along the squall line. A considerable amount of severe weather was generated during the evening as this occurred. Along the squall line, high winds and hail were common with the dominant mode of severe weather being hail of up to golf ball in size. As the MCS out of Nebraska advanced east, a tail extending south from the centroid took on a bow echo configuration and raced east across Iowa at 65 MPH. Very high winds occurred with this feature with numerous locations reporting winds of 65 to 85 MPH. Some of the higher winds included an 85 MPH wind gust in the Winterset area and numerous reports of 75 to 85 MPH winds from Madison, Dallas, Warren and Polk Counties. Lightning struck a house in Ankeny. The house was set on fire by the strike.
33.01999-07-02242°34'N / 92°49'W42°32'N / 92°39'W8.50 Miles50 Yards0075K3KGrundy
 Brief Description: A very active weather pattern was in place over the central U.S. A strong west-northwest wind flow was in place over the state. Meanwhile a warm front was lifting north from the southern Plains. The warm front separated the cooler and dry air to the north from very humid air to the south. Dew point temperatures in the air to the south of the front were in the mid 70s to low 80s. Precipitable water values were near 2 inches as well. A meso scale convective system formed over north central Nebraska and south central South Dakota during the previous night. The remains of this system drifted into west central Iowa during the predawn hours. One cell became severe during the morning. This was to be the pattern for much of the rest of the day as the cells that formed became super cellular, with each supercell lasting about 2 hours. By the early afternoon hours, surface based CAPE values were approaching 6000 J/kg just to the south of the thunderstorm genesis region. Once the storms formed they became supercells quickly. Very strong sheer was in place with strong southeast surface winds veering to westerly winds in the mid levels. Even though freezing levels were in excess of 15,000 feet, the storms were prolific hail producers. WSR-88D VIL values with many of the supercells exceeded 90 kg/m/m. There was also some high winds with the storms at times as many of the cells were rotating as was seen with WSR-88D imagery. The first high winds occurred early in the severe event as 64 MPH winds blasted into the Dow City area of Crawford County. Winds of 66 MPH were recorded at the Denison Municipal Airport as the storm moved through. Damage was reported in many areas of the county. During the day there were also other spotty reports of wind damage, however most of the were were in the 40 to 50 MPH range. A few other cells did produce severe criteria winds as they moved into the central and northeast counties of the state with wind damage reported in Hardin, Hamilton, and Boone Counties. These storms developed during the period of time the weather system was changing from a supercell type system into more of a multi-cell system. The main severe weather event of the day was the hail. Hail reports of one inch up to golf ball size were too numerous to mention. Some of the hail was larger than tennis balls. Baseball size hail fell in Guthrie County, into Adair and Dallas Counties as one of the cells advanced east-southeast. The largest hail actually fell east of Casey in Guthrie County. Softball size hail fell there, smashing windshields on numerous cars. Needless to say, crop damage was widespread from west central into central Iowa along the paths of the two to three supercells that moved through the area. Scattered crop damage occurred with the multi-cellular storms over central into northeast Iowa as well. An example of the damage caused by the hail came by way of a report from Crawford County. Reports indicated hail damaged 80,000 to 100,000 acres of crops with widespread damage. Roads and ditches sustained between $150,000 and $200,000 in damage. Tree removal in the county was #30,000, with $100,000 damage to homes and businesses in the county. By the early evening, the weather system had made a transition from severe weather to heavy rain. Intense rainfall occurred over northeast Iowa. Flash flooding was widespread over northern Grundy, southern Butler, southern Bremer, and most of Black Hawk Counties. A large swath of 6 to 8 inch rainfall occurred over the Beaver Creek basin, causing flash flooding in the area and an eventual flood of near record proportions. County officials reported the flooding as very serious with countless roads and highways under water. Cars were stranded and thousands of basements were flooded by the onslaught of heavy rain. One report indicated several head of cattle lost as they were drown by the flood waters in Grundy County. No doubt, this was not the only case of livestock loss due to the flooding. Another report from the Dewar area, east of Waterloo, indicated about a block of railroad was washed out. Damage there was reported to 33 houses, a car repair shop, and a tavern. Rainfall was in excess of three inches per hour in many areas. The heaviest rainfall officially was around 9 inches. Some unofficial reports in the Cedar Falls area included up to 9 inches of rainfall in a 90 minute period. The observer at Parkersburg picked up 6.55 inches of rain in under 3 hours. A bucket survey in the area showed rainfall of 11 to 14 inches at a few locations in Butler County. The heavy rain occurred as a series of storms formed and trained over the same areas. The complex of thunderstorms that developed was a back developing complex. Late in the life of the system, one of the storms became severe. This storm displayed a meso circulation on the WSR-88D in Johnston, IA, though it was not all that well formed. The storm was the last in the series of storms and layed down a path of damage. The swath was about 13 miles long, extending across southern Butler and northern Grundy Counties. The damage path looked to be more downburst in nature, though there were reports of a tornado imbedded in the flow pattern. The situation was not all that different from the meso cyclone/tornado system that moved through Boone, Dallas, and Polk Counties about a year earlier on 29 June 1998. The tornado caused damage to several farmsteads along the road. The worst hit was on farmstead where all of the farm buildings were destroyed and only the superstructure of the farmhouse remained. Debris was wrapped up in trees for many miles along the path. One other tornado did occur earlier in the day. The tornado came from one of the supercells over western Iowa. A relatively small tornado touched down in Audubon County west of Hamlin. There was little damage reported with this tornado.
33.12004-06-11343°24'N / 92°33'W43°32'N / 92°33'W8.00 Miles150 Yards00190K30KHoward
 Brief Description: A small but intense supercell thunderstorm produced three tornadoes in northeast Iowa. The first tornado touched down about 4 miles southeast of New Haven (Mitchell County), south of 320th Street and between Walnut and Windfall Avenue. It tracked north, primarily in open fields, and lifted between 350th and 360th Street east of New Haven, or just west of Windfall Avenue. The tornado was rated an F1. The second tornado touched down just east of the Mitchell-Howard County line, about 4 miles south of Riceville (Howard County), and also moved straight north. It downed a few trees, but primarily crossed open fields until it reached the southeast side of Riceville. It damaged a few sheds and buildings in Riceville, with mainly tin roofing material and siding blown off. The tornado lifted in Riceville and was rated an F0. The third and most significant tornado formed about 2 miles north of Riceville, again just east of the Mitchell-Howard County line. The tornado tracked north, just east of the county line or Addison Avenue. It grew in strength and at one point was approximately 150 yards wide, hitting several homes and farms (F2 damage). One home lost the roof and all buildings. The tornado was so close to the county line that debris was thrown across Addison Avenue into Mitchell County at times. The dirt and young crops were scoured by the tornado. The tornado crossed into Minnesota just southwest of Le Roy (Mower County), hitting a home directly on the state line. The home, which was built in1900, and several buildings on the lot, were completely demolished (F3 damage).
33.61967-04-30343°20'N / 93°12'W43°34'N / 93°04'W17.20 Miles800 Yards002.5M0Worth
33.61990-06-28342°38'N / 93°10'W42°33'N / 93°03'W7.00 Miles90 Yards002.5M0Franklin
33.81965-05-05443°23'N / 92°33'W43°23'N / 92°09'W19.90 Miles200 Yards0525K0Howard
34.31973-09-26242°58'N / 93°29'W2.00 Miles100 Yards0025K0Cerro Gordo
35.31967-04-30443°27'N / 93°10'W43°30'N / 93°07'W3.00 Miles500 Yards012.5M0Worth
35.31990-06-28342°33'N / 93°03'W42°32'N / 93°01'W2.00 Miles90 Yards002.5M0Hardin
35.91953-05-10443°04'N / 93°31'W43°10'N / 93°30'W6.40 Miles33 Yards03250K0Hancock
36.31966-04-19242°51'N / 92°07'W42°55'N / 92°07'W4.60 Miles250 Yards0025K0Bremer
36.72004-06-11343°30'N / 92°33'W43°33'N / 92°34'W4.00 Miles150 Yards003.0M20KMower
 Brief Description: A tornado crossed the Minnesota-Iowa state line just southwest of Le Roy (Mower County) causing considerable damage. One home right on the state line was completely destroyed, but there were no injuries or deaths. The tornado was approximately 150 yards wide at times and apparently reached F3 damage intensity right on the state line around 6:05 p.m. The tornado then started to weaken, but did heavy damage to a grain company (Koch Industries)(F2 damage) about 2 miles west of Le Roy and continued north, crossing Highway 56 just before 6:10 p.m. The tornado lifted approximately 4 miles northwest of Le Roy in open fields. There were also brief tornado touch downs (all rated F0) near Dexter (Mower County) and Le Roy, as well as areas along the Mower-Fillmore County line west of Spring Valley (Fillmore County).
36.81964-08-29243°18'N / 93°26'W2.00 Miles100 Yards0025K0Worth
37.41953-05-10443°10'N / 93°30'W43°27'N / 93°23'W20.20 Miles33 Yards00250K0Cerro Gordo
37.51953-05-10443°27'N / 92°24'W43°30'N / 92°23'W1.90 Miles33 Yards020K0Howard
38.21981-04-10242°50'N / 92°06'W0.80 Mile100 Yards002.5M0Bremer
38.31971-07-12443°03'N / 92°03'W43°04'N / 92°03'W1.10 Miles1320 Yards042.5M0Fayette
38.31967-04-30443°30'N / 93°07'W43°34'N / 93°07'W4.60 Miles33 Yards0025.0M0Freeborn
38.81968-05-15243°20'N / 92°11'W43°17'N / 92°06'W4.70 Miles250 Yards0025K0Howard
38.91995-07-27243°34'N / 92°44'W43°36'N / 92°41'W3.50 Miles40 Yards0005.0MMower
 Brief Description: A tornado touched down in Adams and moved northeast touching down several times. Several buildings were damaged or destroyed. Many trees uprooted. A church in Adams lost its steeple and bell tower.
39.11973-09-26243°01'N / 93°35'W1.00 Mile50 Yards0025K0Hancock
39.22008-05-25242°34'N / 92°33'W42°37'N / 92°04'W24.00 Miles2100 Yards02025.0M155KBlack Hawk
 Brief Description: EVENT NARRATIVE: Tornado moved in from Butler County and became very broad as it headed toward Fairbank. Tornado lifted on the Buchanan County border. EPISODE NARRATIVE: A very intense upper low was located over the southwest U.S. and lifted northeast during the weekend of the 24th into the morning of the 26th. The seasons first strong push of deep moisture moved into Iowa on the 25th with surface temperatures warming into the mid 80s and dew points surging into the upper 60s to low 70s. Precipitable water values were near 1.5 inches. The dry slot pushed north across the area the previous night as the warm front lifted north. The primary surface low was located over northern Minnesota. A cold front extended south from the low into northwest Iowa. The airmass became very unstable by the mid afternoon hours. MUCAPE rose to between 4000 and 5000 J/kg. Lifted indices fell to -8 to -11 C. There was a considerable amount of both DCAPE at 1000-1500 J/kg and cape in the -10 to-30 C. layer of the atmoshpere, between 400 and 600 J/kg. The freezing level was around 13,200 feet. The environment was quite sheared with effective shear in the 40 to 50 kt range. LCL values were between 1000 and 1500 meters. The airmass was initially capped. During the late afternoon hours, a small cluster of thunderstorms formed over north central into northeast Iowa. The storms became severe very quickly. Initially, the storms dropped hail up to golf ball in size. One became a strong super cell and produced a major tornado. This cell, in addition to being tornadic, also produced hail of baseball to softball in size and winds in excess of 90 MPH. The tornado track was from approximately 2 miles south of Aplington to Parkersburg, then continued to New Hartford and across northern Black Hawk County. The average path width ranged from 0.6 to 0.7 miles near Parkersburg to just north of New Hartford. The path constricted to near one quarter mile wide east of New Hartford to north of Waterloo. The width then increased to near 1.2 miles wide north of Dunkerton before dissipating near the Black Hawk and Buchanan County line. The tornado was on the ground for approximately 43 miles. In addition to the main tornado, a satellite tornado was observed by storm chasers and one off duty NWS employee. It was located south of the main tornado and was on the ground for a little over a mile in Grundy County. Initial reports indicated 9 fatalities with 7 in Parkersburg (pop 1889) and 2 in New Hartford (pop 637). There were at least 50 injuries, with 4 of those in critical condition. Two of the fatalities occurred a few days after the tornado from injuries sustained in the tornado. The last fatality occurred on 7 Nov. A 61 year old female sustained injuries in the stairwell of her home when a 2 x 4 was thrown through her right side lung. She was hospitalized and died several months later of complications. Significant structural damage occurred across the southern end of Parkersburg and along a path to just north of New Hartford. Numerous structures completely destroyed from Parkersburg to near New Hartford. The tornado continued eastward to just north of the Waterloo and Cedar Falls area. Significant damage also occurred north of Dunkerton where the tornado increased to its greatest path width. This storm also produced substantial straight line wind damage along the southern periphery of the storm just south of the tornado track. News accounts indicated that a receipt from Parkersburg was found around 1915 CST 3 miles north of Prairie du Chien, WI, 109 miles to the northeast. Receipits were also found in Clayton County at Elkader, and full scrapbook pages and photos were found in far northeast Bremer County at Sumner. Preliminary estimates that straight line winds of 90 to 100 MPH occurred with this storm. At 1637 CST, the Waterloo Airport recorded a 93 MPH wind gust. Survey results suggest that straight line wind damage was the cause of the severe damage at the recreational vehicle dealership north of Cedar Falls. At least 627 homes were damaged, including 288 homes destroyed in Parkersburg, 88 in New Hartford, 15 in Hazelton and another 50 in Black Hawk County. In addition, 58 had major damage, 33 had moderate damage, 2 were inaccessible, and 93 damaged but able to be occupied. There were also 21 businesses destroyed. Governor Chet Culver declared both Butler and Black Hawk disaster areas with both given the State Declaration. A Federal Disaster Declaration occurred two days later for both Butler and Black Hawk Counties. The tornado was rated a low end EF5 by a Quick Response Team (QRT) in portions of Parkersburg and north of New Hartford with peak winds estimated at 205 MPH. For historical reference, the last F5 tornado to hit Iowa was on 13 June 1976 in Boone and Story Counties in the town of Jordan, with a 21 mile path length. The last F4 tornado to hit Iowa was in Union, Madison, and Dallas Counties with a 56 mile path length on 8 April 1999. There was one other smaller tornado during the evening. A tornado touched down in Clarke County and was on the ground for a short time southeast of Osceola. After the initial thunderstorm area developed over north central and northeast Iowa, a large complex developed over southeast Nebraska. The two areas of storms filled in to form a squall line by the mid evening hours. The complex over Nebraska then pushed east and northeast along the squall line. A considerable amount of severe weather was generated during the evening as this occurred. Along the squall line, high winds and hail were common with the dominant mode of severe weather being hail of up to golf ball in size. As the MCS out of Nebraska advanced east, a tail extending south from the centroid took on a bow echo configuration and raced east across Iowa at 65 MPH. Very high winds occurred with this feature with numerous locations reporting winds of 65 to 85 MPH. Some of the higher winds included an 85 MPH wind gust in the Winterset area and numerous reports of 75 to 85 MPH winds from Madison, Dallas, Warren and Polk Counties. Lightning struck a house in Ankeny. The house was set on fire by the strike.
39.41988-03-24243°04'N / 92°02'W43°07'N / 92°02'W2.00 Miles100 Yards002.5M0Fayette
39.41971-07-12242°50'N / 92°06'W42°50'N / 92°03'W00250K0Bremer
39.41964-08-29243°22'N / 93°27'W43°29'N / 93°17'W11.20 Miles150 Yards0025K0Worth
39.41967-03-30243°11'N / 92°06'W43°14'N / 92°02'W4.10 Miles100 Yards0025K0Howard
40.31966-04-19242°27'N / 92°36'W42°29'N / 92°33'W2.30 Miles200 Yards0025K0Grundy
41.21966-10-14542°48'N / 93°39'W42°55'N / 93°32'W9.70 Miles1000 Yards617225.0M0Wright
41.82000-05-11342°31'N / 92°27'W42°36'N / 92°07'W18.50 Miles400 Yards1251.8M10KBlack Hawk
 Brief Description: Multi-vortex, regerative tornado F72PH The seasons first tornado outbreak took place during the late afternoon and early evening hours of the 11th. During the day, very strong warm air advection took place. Temperatures warmed rapidly during the day with highs reaching the mid to upper 90s over about the southwest half of the state. Dew point temperatures were in the upper 60s to low 70s. This combination produced CAPE values in excess of 8000 J/kg. During the afternoon, a strong cap was in place with 700 mb temperatures around +16 C. This prevented convection from firing during the afternoon. Toward evening, thunderstorms broke through the cap over northeast Iowa. The storms went from initial echo to tornadic storms in less than 50 minutes. A supercell formed west of the Waterloo area. This cell became a splitting cell and produced a brief tornado in Grundy County as the right moving cell split off, and golf ball size hail in Bremer County from the left moving cell. The cell moved off quickly, however additional supercells back developed over the same area. the strongest tornado developed in the Cedar Falls area and tracked across the northern portions of Waterloo. This cell produced a strong tornado which was actually a multi-vortex tornado based on reports from storm chasers in the area. At one point, west of Dunkerton, three tornadoes each one quarter mile wide were on the ground with this storm. The tornado damaged several houses and a few farmsteads along the way. Reports indicated between 5 and 10 houses in Black Hawk County were totally destroyed, and another 15 to 20 sustained significant damage. A total of at least 41 structures sustained at least some damage. In addition to the tornado, damage also occurred south of the track as RFD winds estimated as high as 100 MPH were observed. Dunkerton was hard hit as the tornado moved through. Heavy damage was reported at a coop elevator in Dunkerton, with 10 of 16 grain elevators damaged. A roof was removed from a church as well, resulting in about $500,000 damage. The City Hall building was destroyed in Dunkerton. The City Hall was housed in a series of double wide trailers since ironically the former City Hall building was destroyed just last year in the floods of '99. As the tornado moved through the fairly densely populated area, numerous injuries were reported. Some of the injuries were severe with limbs being cut off by flying debris. One woman lost both one arm and one hand, and had her back broken. She passed away 17 days after her injuries occurred. Six of the injuries occurred at a nursing home that was hit by the tornado. They occurred as the 139 residents were being evacuated. Reports indicated the width of the tornado was up to three-quarters of a mile at its widest. The damage path from the storm was around one and one half miles wide. The tornado continued moving east and crossed into Buchanan County, about 4 miles northeast of Dunkerton. A short time later, another cell developed in the Dunkerton area and dropped a tornado. That tornado struck a farm northwest of town, destroying the farm house and seven outbuildings. In addition to the damage that occurred to the structures, the family dog and one of the five horses on the farm were killed. Reports indicate a letter from one of the farm houses destroyed was found 60 miles away from Dunkerton in the town of Monona in Clayton County. Polly Mill's rural Dunkerton farmhouse was shredded by the tornado. She lost some of her late husband's military medals, pages out of the family Bible, and part of her collection of letters and first-issue stamps. Sixty miles away, on a farm east of Monona, the letter was found in an envelope carrying a first-day issue, 5-cent stamp commemorating the Battle of New Orleans. There was yet a third round of tornadic storms in the Dunkerton area. The last tornado touched down near Dunkerton and developed southward. Two houses in the town of Dunkerton were destroyed by this tornado. In addition to the tornadoes, very heavy rain fell in a narrow area of Black Hawk County. Reports of 3 inches or more of rain was received from the area. Soil conditions were very dry at the time. The dry soil conditions helped preclude any significant flooding. By the afternoon of the 12th, Iowa Governor Vilsack had declared Black Hawk County a state disaster area.
42.51988-03-24243°07'N / 92°02'W43°11'N / 91°56'W7.00 Miles33 Yards002.5M0Winneshiek
42.61971-07-12242°53'N / 92°03'W42°49'N / 91°57'W6.40 Miles100 Yards00250K0Fayette
43.11984-06-07243°38'N / 92°59'W43°39'N / 92°54'W5.00 Miles100 Yards072.5M0Mower
43.21966-10-14242°23'N / 92°56'W42°26'N / 92°58'W2.70 Miles100 Yards003K0Grundy
43.31967-04-30243°38'N / 92°56'W43°40'N / 92°51'W3.80 Miles33 Yards0025.0M0Mower
43.41965-05-05443°23'N / 92°09'W43°25'N / 92°05'W3.30 Miles200 Yards0025K0Howard
43.42000-05-11242°34'N / 92°14'W42°36'N / 92°10'W3.60 Miles120 Yards00350K5KBlack Hawk
 Brief Description: Farm and several outbuildings destroyed The seasons first tornado outbreak took place during the late afternoon and early evening hours of the 11th. During the day, very strong warm air advection took place. Temperatures warmed rapidly during the day with highs reaching the mid to upper 90s over about the southwest half of the state. Dew point temperatures were in the upper 60s to low 70s. This combination produced CAPE values in excess of 8000 J/kg. During the afternoon, a strong cap was in place with 700 mb temperatures around +16 C. This prevented convection from firing during the afternoon. Toward evening, thunderstorms broke through the cap over northeast Iowa. The storms went from initial echo to tornadic storms in less than 50 minutes. A supercell formed west of the Waterloo area. This cell became a splitting cell and produced a brief tornado in Grundy County as the right moving cell split off, and golf ball size hail in Bremer County from the left moving cell. The cell moved off quickly, however additional supercells back developed over the same area. the strongest tornado developed in the Cedar Falls area and tracked across the northern portions of Waterloo. This cell produced a strong tornado which was actually a multi-vortex tornado based on reports from storm chasers in the area. At one point, west of Dunkerton, three tornadoes each one quarter mile wide were on the ground with this storm. The tornado damaged several houses and a few farmsteads along the way. Reports indicated between 5 and 10 houses in Black Hawk County were totally destroyed, and another 15 to 20 sustained significant damage. A total of at least 41 structures sustained at least some damage. In addition to the tornado, damage also occurred south of the track as RFD winds estimated as high as 100 MPH were observed. Dunkerton was hard hit as the tornado moved through. Heavy damage was reported at a coop elevator in Dunkerton, with 10 of 16 grain elevators damaged. A roof was removed from a church as well, resulting in about $500,000 damage. The City Hall building was destroyed in Dunkerton. The City Hall was housed in a series of double wide trailers since ironically the former City Hall building was destroyed just last year in the floods of '99. As the tornado moved through the fairly densely populated area, numerous injuries were reported. Some of the injuries were severe with limbs being cut off by flying debris. One woman lost both one arm and one hand, and had her back broken. She passed away 17 days after her injuries occurred. Six of the injuries occurred at a nursing home that was hit by the tornado. They occurred as the 139 residents were being evacuated. Reports indicated the width of the tornado was up to three-quarters of a mile at its widest. The damage path from the storm was around one and one half miles wide. The tornado continued moving east and crossed into Buchanan County, about 4 miles northeast of Dunkerton. A short time later, another cell developed in the Dunkerton area and dropped a tornado. That tornado struck a farm northwest of town, destroying the farm house and seven outbuildings. In addition to the damage that occurred to the structures, the family dog and one of the five horses on the farm were killed. Reports indicate a letter from one of the farm houses destroyed was found 60 miles away from Dunkerton in the town of Monona in Clayton County. Polly Mill's rural Dunkerton farmhouse was shredded by the tornado. She lost some of her late husband's military medals, pages out of the family Bible, and part of her collection of letters and first-issue stamps. Sixty miles away, on a farm east of Monona, the letter was found in an envelope carrying a first-day issue, 5-cent stamp commemorating the Battle of New Orleans. There was yet a third round of tornadic storms in the Dunkerton area. The last tornado touched down near Dunkerton and developed southward. Two houses in the town of Dunkerton were destroyed by this tornado. In addition to the tornadoes, very heavy rain fell in a narrow area of Black Hawk County. Reports of 3 inches or more of rain was received from the area. Soil conditions were very dry at the time. The dry soil conditions helped preclude any significant flooding. By the afternoon of the 12th, Iowa Governor Vilsack had declared Black Hawk County a state disaster area.
43.61961-09-02242°39'N / 92°07'W1.00 Mile40 Yards0025K0Howard
43.71976-06-12242°32'N / 92°13'W42°38'N / 92°10'W6.90 Miles100 Yards0225K0Black Hawk
44.01999-08-09243°24'N / 93°31'W43°24'N / 93°31'W3.50 Miles40 Yards0050K5KWorth
 Brief Description: An unstable airmass was in place over Iowa during the afternoon and evening hours of the 9th. Satellite and sounding data suggested the atmosphere was capped at about 775 mb by a warm layer of air with temperatures as high as 18 C. or more. Thunderstorms had a hard time firing off. A cold front moved southeast into the state as rich low level air with dew point temperatures in the mid 70s preceded the front. While the front moved southeast, a speed max near 100 kts in strength moved into the north central U.S. This combined with an upper level short wave helped a few of the storms break the cap. The wind profile was favourable with a strong shearing environment. Thunderstorms moved into north central Iowa and became tornadic quickly. There was basically one cell that produced at least two tornadoes as it slipped southeast into Iowa. The first tornado touched down in Winnebago County near Scarville. The tornado moved southeast across the county and advanced into Worth County by a few miles. The tornado caused crop damage and some building damage along its path. The corner of a bank building was torn off in the town of Joice in Worth County for example. The same cell produced another brief tornado touchdown near Burchinal in Cerro Gordo County near the intersection of I-35 and County Highway B-43. No significant damage was reported with this tornado. As the large cell that produced the tornado moved on, the rear flank downdraft produced high winds once again in the Scarville area. Power lines were downed and a few buildings were damaged by the high winds in the town of Scarville. High winds also struck the airport in Mason City with a wind gust of 58 MPH.
44.42001-05-01243°34'N / 93°17'W43°37'N / 93°10'W7.00 Miles440 Yards0020.0M0Freeborn
 Brief Description: Tornado first touched down on the western fringe of Glenville, and produced major damage, especially on the northwest side of Glenville. There were 25 homes that sustained major damage, and 70 with minor damage. Damage survey indicated F2 damage on northwest side of Glenville, with F1 damage along rest of path.
44.51980-09-20243°26'N / 93°30'W43°27'N / 93°28'W002.5M0Worth
44.81965-09-09243°23'N / 92°04'W1.00 Mile50 Yards0025K0Howard
44.81961-08-04243°40'N / 92°57'W2.00 Miles600 Yards02250K0Mower
45.11991-03-22242°16'N / 92°59'W42°29'N / 92°47'W19.00 Miles50 Yards00250K0Grundy
45.21980-09-20243°19'N / 93°38'W43°26'N / 93°30'W10.20 Miles60 Yards002.5M0Winnebago
45.41953-05-20342°18'N / 93°18'W42°33'N / 93°03'W21.30 Miles400 Yards000K0Hardin
45.52009-06-17243°43'N / 93°01'W43°38'N / 92°54'W10.00 Miles120 Yards002.0M30KMower
 Brief Description: EVENT NARRATIVE: A tornado caused damage on the north and northeast side of the city of Austin. Specific reports included minor tree damage, as well as debris blown into fences and bent poles on the northwest side of Austin. Several power poles were snapped off or bent along Highway 218 on the north side of the city. Several metal work buildings were heavily damaged along 243rd St, along with numerous trees and some minor roof damage to nearby homes. Large debris, such as metal dumpsters, were tossed large distances. There was straight-line wind damage noted south of the tornado path, or along Highway 218 and 4th St NW. Several homes had minor damage, with numerous trees blown over or sheared off along 236th and 237th Street directly north of downtown Austin. There was considerable damage done in Todd Park, including athletic equipment, small buildings and hundreds of trees toppled and uprooted. The north side of the park, including the northern softball fields had the most damage. There was also considerable tree damage along 21st St NE or 555th Ave, which continued into the Austin Country Club. Minor damage was noted about a half mile east of the Austin airport and about 2 miles southeast of the airport. One minor injury was reported when a man sustained scrapes and bruises when he took shelter in a shed that rolled over twice. EPISODE NARRATIVE: Severe thunderstorms were triggered along a warm front during the evening of June 17. One of the storms produced two known tornadoes, one that initially touched down near the Dodge and Mower County line, northwest of the city of Austin. The tornado then moved through far north sections of Austin to areas about 3 miles east of Austin. The worst tornado damage was considered EF2 about 3 miles north of downtown near the intersection of 243rd and 4th street northwest. The bulk of the remaining damage was considered EF0 and EF1. The tornado was on the ground from approximately 8:00 p.m. until 8:23 p.m. Path length was about 10 miles long and had a maximum width of 120 yards. Another small tornado touched down southeast of this track in open country in rural Mower County.
45.91964-05-07242°31'N / 92°20'W42°28'N / 92°12'W7.10 Miles200 Yards02725.0M0Black Hawk
46.02001-05-01243°39'N / 93°08'W43°40'N / 93°03'W5.00 Miles250 Yards002.0M0Freeborn
 Brief Description: Shortly after the Glenville tornado dissipated, another tornado formed 4 miles southwest of Oakland and dissipated about 1/2 mile before it would have crossed Interstate 90, which law enforcement had barricaded. Major damage to 3 farmsteads, minor damage to 8 others per damage survey.
46.11965-05-05243°30'N / 92°36'W43°48'N / 92°22'W23.60 Miles33 Yards0025K0Mower
46.81999-08-09243°28'N / 93°37'W43°23'N / 93°30'W8.00 Miles40 Yards00100K10KWinnebago
 Brief Description: An unstable airmass was in place over Iowa during the afternoon and evening hours of the 9th. Satellite and sounding data suggested the atmosphere was capped at about 775 mb by a warm layer of air with temperatures as high as 18 C. or more. Thunderstorms had a hard time firing off. A cold front moved southeast into the state as rich low level air with dew point temperatures in the mid 70s preceded the front. While the front moved southeast, a speed max near 100 kts in strength moved into the north central U.S. This combined with an upper level short wave helped a few of the storms break the cap. The wind profile was favourable with a strong shearing environment. Thunderstorms moved into north central Iowa and became tornadic quickly. There was basically one cell that produced at least two tornadoes as it slipped southeast into Iowa. The first tornado touched down in Winnebago County near Scarville. The tornado moved southeast across the county and advanced into Worth County by a few miles. The tornado caused crop damage and some building damage along its path. The corner of a bank building was torn off in the town of Joice in Worth County for example. The same cell produced another brief tornado touchdown near Burchinal in Cerro Gordo County near the intersection of I-35 and County Highway B-43. No significant damage was reported with this tornado. As the large cell that produced the tornado moved on, the rear flank downdraft produced high winds once again in the Scarville area. Power lines were downed and a few buildings were damaged by the high winds in the town of Scarville. High winds also struck the airport in Mason City with a wind gust of 58 MPH.
46.81971-05-31242°24'N / 92°27'W1.00 Mile200 Yards0025K0Black Hawk
47.11982-05-17343°35'N / 93°17'W43°42'N / 93°08'W10.00 Miles100 Yards00250K0Freeborn
47.11965-05-05443°25'N / 92°05'W43°27'N / 92°02'W2.30 Miles200 Yards0025K0Winneshiek
47.21976-06-13242°25'N / 92°16'W42°36'N / 92°08'W14.00 Miles100 Yards0025K0Black Hawk
47.62000-05-11242°34'N / 92°10'W42°30'N / 92°08'W5.00 Miles150 Yards00300K2KBlack Hawk
 Brief Description: Two houses destroyed The seasons first tornado outbreak took place during the late afternoon and early evening hours of the 11th. During the day, very strong warm air advection took place. Temperatures warmed rapidly during the day with highs reaching the mid to upper 90s over about the southwest half of the state. Dew point temperatures were in the upper 60s to low 70s. This combination produced CAPE values in excess of 8000 J/kg. During the afternoon, a strong cap was in place with 700 mb temperatures around +16 C. This prevented convection from firing during the afternoon. Toward evening, thunderstorms broke through the cap over northeast Iowa. The storms went from initial echo to tornadic storms in less than 50 minutes. A supercell formed west of the Waterloo area. This cell became a splitting cell and produced a brief tornado in Grundy County as the right moving cell split off, and golf ball size hail in Bremer County from the left moving cell. The cell moved off quickly, however additional supercells back developed over the same area. the strongest tornado developed in the Cedar Falls area and tracked across the northern portions of Waterloo. This cell produced a strong tornado which was actually a multi-vortex tornado based on reports from storm chasers in the area. At one point, west of Dunkerton, three tornadoes each one quarter mile wide were on the ground with this storm. The tornado damaged several houses and a few farmsteads along the way. Reports indicated between 5 and 10 houses in Black Hawk County were totally destroyed, and another 15 to 20 sustained significant damage. A total of at least 41 structures sustained at least some damage. In addition to the tornado, damage also occurred south of the track as RFD winds estimated as high as 100 MPH were observed. Dunkerton was hard hit as the tornado moved through. Heavy damage was reported at a coop elevator in Dunkerton, with 10 of 16 grain elevators damaged. A roof was removed from a church as well, resulting in about $500,000 damage. The City Hall building was destroyed in Dunkerton. The City Hall was housed in a series of double wide trailers since ironically the former City Hall building was destroyed just last year in the floods of '99. As the tornado moved through the fairly densely populated area, numerous injuries were reported. Some of the injuries were severe with limbs being cut off by flying debris. One woman lost both one arm and one hand, and had her back broken. She passed away 17 days after her injuries occurred. Six of the injuries occurred at a nursing home that was hit by the tornado. They occurred as the 139 residents were being evacuated. Reports indicated the width of the tornado was up to three-quarters of a mile at its widest. The damage path from the storm was around one and one half miles wide. The tornado continued moving east and crossed into Buchanan County, about 4 miles northeast of Dunkerton. A short time later, another cell developed in the Dunkerton area and dropped a tornado. That tornado struck a farm northwest of town, destroying the farm house and seven outbuildings. In addition to the damage that occurred to the structures, the family dog and one of the five horses on the farm were killed. Reports indicate a letter from one of the farm houses destroyed was found 60 miles away from Dunkerton in the town of Monona in Clayton County. Polly Mill's rural Dunkerton farmhouse was shredded by the tornado. She lost some of her late husband's military medals, pages out of the family Bible, and part of her collection of letters and first-issue stamps. Sixty miles away, on a farm east of Monona, the letter was found in an envelope carrying a first-day issue, 5-cent stamp commemorating the Battle of New Orleans. There was yet a third round of tornadic storms in the Dunkerton area. The last tornado touched down near Dunkerton and developed southward. Two houses in the town of Dunkerton were destroyed by this tornado. In addition to the tornadoes, very heavy rain fell in a narrow area of Black Hawk County. Reports of 3 inches or more of rain was received from the area. Soil conditions were very dry at the time. The dry soil conditions helped preclude any significant flooding. By the afternoon of the 12th, Iowa Governor Vilsack had declared Black Hawk County a state disaster area.
48.31960-04-16342°20'N / 92°35'W42°22'N / 92°32'W2.30 Miles800 Yards00250K0Grundy
49.01975-11-09342°12'N / 92°28'W42°41'N / 92°03'W39.40 Miles33 Yards002.5M0Tama
49.11960-04-16342°22'N / 92°32'W42°28'N / 92°05'W23.70 Miles800 Yards15250K0Black Hawk
49.91968-05-15542°40'N / 91°56'W42°51'N / 91°51'W13.10 Miles500 Yards515625.0M0Fayette


* 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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