Storm Lake, IA Natural Disasters and Weather Extremes
Hot Rankings
The chance of earthquake damage in Storm Lake is about the same as Iowa average and is much lower than the national average. The risk of tornado damage in Storm Lake is lower than Iowa average and is higher than the national average.
Earthquake Index, #289
| Storm Lake, 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
| Storm Lake, 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, #960
| Storm Lake, IA | 178.88 |
| Iowa | 236.74 |
| U.S. | 136.45 |
The tornado index value is calculated based on historical tornado events data using USA.com algorithms. It is an indicator of the tornado level in a region. A higher tornado index value means a higher chance of tornado events.
Other Weather Extremes Events
A total of 2,934 other weather extremes events within 50 miles of Storm Lake, IA were recorded from 1950 to 2010. The following is a break down of these events:
| Type | Count | Type | Count | Type | Count | Type | Count | Type | Count |
| Avalanche: | 0 | Blizzard: | 32 | Cold: | 16 | Dense Fog: | 0 | Drought: | 9 |
| Dust Storm: | 0 | Flood: | 288 | Hail: | 1,295 | Heat: | 3 | Heavy Snow: | 36 |
| High Surf: | 0 | Hurricane: | 0 | Ice Storm: | 16 | Landslide: | 0 | Strong Wind: | 60 |
| Thunderstorm Winds: | 995 | Tropical Storm: | 0 | Wildfire: | 0 | Winter Storm: | 37 | Winter Weather: | 26 |
| Other: | 121 | ||||||||
Volcanos Nearby
No volcano is found in or near Storm Lake, IA.
Historical Earthquake Events
No historical earthquake events that had recorded magnitudes of 3.5 or above found in or near Storm Lake, IA.
No historical earthquake events found in or near Storm Lake, IA.
Historical Tornado Events
A total of 74 historical tornado events that had recorded magnitude of 2 or above found in or near Storm Lake, IA.
| Distance (miles) | Date | Magnitude | Start Lat/Log | End Lat/Log | Length | Width | Fatalities | Injuries | Property Damage | Crop Damage | Affected County |
| 1.9 | 1969-08-08 | 2 | 42°37'N / 95°12'W | 2.00 Miles | 70 Yards | 0 | 0 | 250K | 0 | Buena Vista | |
| 2.5 | 1984-06-07 | 2 | 42°39'N / 95°12'W | 42°42'N / 95°09'W | 4.00 Miles | 100 Yards | 0 | 3 | 2.5M | 0 | Buena Vista |
| 9.6 | 1957-06-16 | 2 | 42°30'N / 95°24'W | 43°00'N / 94°45'W | 47.60 Miles | 33 Yards | 0 | 0 | 250K | 0 | Ida |
| 12.3 | 1958-08-05 | 2 | 42°45'N / 95°10'W | 42°30'N / 94°45'W | 27.10 Miles | 60 Yards | 0 | 0 | 3K | 0 | Buena Vista |
| 15.3 | 1963-03-16 | 2 | 42°47'N / 95°26'W | 2.00 Miles | 250 Yards | 0 | 0 | 3K | 0 | Cherokee | |
| 16.4 | 1953-06-07 | 2 | 42°22'N / 95°29'W | 42°29'N / 95°10'W | 17.80 Miles | 833 Yards | 0 | 0 | 0K | 0 | Ida |
| 16.9 | 1984-06-07 | 2 | 42°25'N / 95°35'W | 42°35'N / 95°21'W | 16.00 Miles | 150 Yards | 0 | 1 | 2.5M | 0 | Ida |
| 18.7 | 1984-06-07 | 2 | 42°19'N / 95°23'W | 42°27'N / 95°13'W | 12.00 Miles | 100 Yards | 0 | 1 | 2.5M | 0 | Ida |
| 19.7 | 1965-05-15 | 2 | 42°24'N / 95°00'W | 0.50 Mile | 50 Yards | 0 | 0 | 0K | 0 | Sac | |
| 19.7 | 1984-04-26 | 2 | 42°33'N / 94°50'W | 42°39'N / 94°48'W | 7.00 Miles | 20 Yards | 0 | 0 | 2.5M | 0 | Pocahontas |
| 20.1 | 1984-04-26 | 2 | 42°28'N / 94°52'W | 42°33'N / 94°50'W | 5.00 Miles | 20 Yards | 0 | 0 | 2.5M | 0 | Calhoun |
| 22.9 | 2004-06-11 | 3 | 42°55'N / 95°03'W | 42°59'N / 95°00'W | 6.00 Miles | 400 Yards | 0 | 0 | 50K | 0 | Clay |
| Brief Description: A large cone shaped tornado tore a steel bridge from a road. The tornado raised a large debris cloud as it moved over open country, causing damage to crops and power lines. The tornado moved into Clay County after forming just south of the County Line. | |||||||||||
| 23.4 | 1984-04-26 | 2 | 42°19'N / 94°55'W | 42°28'N / 94°52'W | 10.00 Miles | 200 Yards | 0 | 0 | 2.5M | 0 | Sac |
| 23.7 | 1984-06-07 | 2 | 42°39'N / 95°44'W | 42°46'N / 95°35'W | 10.00 Miles | 77 Yards | 0 | 0 | 2.5M | 0 | Cherokee |
| 25.2 | 1954-04-26 | 2 | 43°03'N / 95°18'W | 42°58'N / 95°10'W | 8.40 Miles | 33 Yards | 0 | 0 | 0K | 0 | Clay |
| 25.3 | 1952-06-23 | 4 | 42°45'N / 95°51'W | 42°54'N / 95°25'W | 24.10 Miles | 400 Yards | 0 | 4 | 2.5M | 0 | Cherokee |
| 25.8 | 1958-04-01 | 2 | 42°44'N / 95°42'W | 42°51'N / 95°38'W | 8.30 Miles | 200 Yards | 0 | 0 | 25K | 0 | Cherokee |
| 26.1 | 1984-06-07 | 2 | 42°51'N / 94°51'W | 42°55'N / 94°45'W | 10.00 Miles | 100 Yards | 0 | 1 | 2.5M | 0 | Pocahontas |
| 27.0 | 1975-06-04 | 2 | 43°02'N / 95°09'W | 0 | 0 | 3K | 0 | Clay | |||
| 27.3 | 1991-04-26 | 3 | 42°13'N / 95°12'W | 42°17'N / 95°06'W | 6.00 Miles | 150 Yards | 0 | 0 | 2.5M | 0 | Sac |
| 27.8 | 1995-05-27 | 4 | 42°04'N / 94°54'W | 42°35'N / 94°50'W | 37.00 Miles | 400 Yards | 0 | 0 | 3.0M | 43K | Carroll, Sac, Calhoun And Pocahontas |
| Brief Description: Multiple vortex at times. | |||||||||||
| 28.6 | 1986-07-28 | 2 | 42°33'N / 94°41'W | 42°33'N / 94°37'W | 4.00 Miles | 150 Yards | 0 | 0 | 250K | 0 | Calhoun |
| 29.8 | 2008-06-11 | 2 | 43°00'N / 95°16'W | 43°09'N / 95°06'W | 13.00 Miles | 100 Yards | 0 | 0 | 300K | 0K | Clay |
| Brief Description: EVENT NARRATIVE: A tornado destroyed or heavily damaged numerous outbuildings on at least 8 affected farmsteads, with damaged buildings including several large sheds. The tornado damaged numerous grain bins, most of which were carried off their foundations, with some being carried as much as a half mile. The ornado also overturned a camper, blew the top off a silo, destroyed a garage, broke windows on a house, and caused considerable damage to trees, power poles, and power lines. EPISODE NARRATIVE: Thunderstorms produced several tornadoes, along with large hail, damaging winds, and flash flooding in northwest Iowa during the late afternoon and early evening of June 11th. | |||||||||||
| 29.9 | 2008-06-11 | 2 | 42°58'N / 95°32'W | 43°03'N / 95°30'W | 6.00 Miles | 300 Yards | 0 | 0 | 200K | 0K | O'brien |
| Brief Description: EVENT NARRATIVE: A tornado destroyed several outbuildings, moved a 1.5 ton wagon, heavily damaged a machine shed containing farm equipment and also damaged a nearby house on the same farm. Also destroyed another machine shed at a different location, destroyed a pole barn, damaged a grain bin, broke or blew down several power poles and power lines, and caused tree damage. EPISODE NARRATIVE: Thunderstorms produced several tornadoes, along with large hail, damaging winds, and flash flooding in northwest Iowa during the late afternoon and early evening of June 11th. | |||||||||||
| 31.0 | 1979-06-28 | 4 | 42°38'N / 94°36'W | 42°34'N / 94°35'W | 4.10 Miles | 33 Yards | 0 | 0 | 3K | 0 | Pocahontas |
| 32.0 | 1991-08-07 | 2 | 42°49'N / 95°49'W | 42°45'N / 95°47'W | 5.00 Miles | 80 Yards | 0 | 0 | 25K | 0 | Cherokee |
| 32.5 | 1971-10-01 | 3 | 43°02'N / 95°29'W | 43°09'N / 95°19'W | 11.20 Miles | 33 Yards | 0 | 0 | 250K | 0 | O'brien |
| 32.7 | 1984-06-07 | 2 | 42°50'N / 94°42'W | 42°56'N / 94°35'W | 8.00 Miles | 100 Yards | 0 | 0 | 2.5M | 0 | Pocahontas |
| 33.9 | 1980-07-19 | 2 | 43°01'N / 95°37'W | 43°04'N / 95°34'W | 3.30 Miles | 160 Yards | 0 | 0 | 2.5M | 0 | O'brien |
| 33.9 | 1990-06-19 | 2 | 42°48'N / 94°32'W | 42°34'N / 94°32'W | 14.00 Miles | 77 Yards | 0 | 0 | 2.5M | 0 | Pocahontas |
| 34.5 | 1990-06-19 | 2 | 42°34'N / 94°32'W | 42°32'N / 94°32'W | 2.00 Miles | 77 Yards | 0 | 0 | 2.5M | 0 | Calhoun |
| 34.7 | 1965-05-15 | 2 | 42°23'N / 94°37'W | 0.50 Mile | 50 Yards | 0 | 0 | 0K | 0 | Calhoun | |
| 35.0 | 1980-07-19 | 2 | 42°50'N / 94°50'W | 43°01'N / 94°25'W | 24.40 Miles | 80 Yards | 0 | 0 | 2.5M | 0 | Palo Alto |
| 35.0 | 1980-09-20 | 3 | 43°09'N / 95°09'W | 1.50 Miles | 300 Yards | 0 | 0 | 25K | 0 | Clay | |
| 35.0 | 1984-06-07 | 2 | 43°09'N / 95°09'W | 2.00 Miles | 77 Yards | 0 | 0 | 250K | 0 | Clay | |
| 35.5 | 1991-08-07 | 2 | 42°49'N / 95°54'W | 42°49'N / 95°49'W | 3.00 Miles | 80 Yards | 0 | 0 | 25K | 0 | Plymouth |
| 35.5 | 1969-07-26 | 3 | 42°20'N / 95°36'W | 42°02'N / 95°25'W | 22.50 Miles | 200 Yards | 0 | 0 | 250K | 0 | Ida |
| 35.6 | 1954-06-09 | 4 | 42°17'N / 94°43'W | 42°23'N / 94°34'W | 9.90 Miles | 440 Yards | 1 | 0 | 250K | 0 | Calhoun |
| 35.8 | 1972-06-07 | 2 | 42°09'N / 94°59'W | 2.00 Miles | 200 Yards | 0 | 0 | 3K | 0 | Carroll | |
| 36.0 | 1964-09-07 | 2 | 42°47'N / 95°58'W | 42°47'N / 95°48'W | 7.90 Miles | 200 Yards | 0 | 0 | 250K | 0 | Plymouth |
| 36.3 | 1984-06-07 | 2 | 42°55'N / 94°45'W | 43°02'N / 94°32'W | 15.00 Miles | 100 Yards | 0 | 1 | 2.5M | 0 | Palo Alto |
| 36.3 | 1979-06-28 | 4 | 42°34'N / 94°35'W | 42°27'N / 94°26'W | 10.80 Miles | 333 Yards | 3 | 26 | 25.0M | 0 | Calhoun |
| 36.4 | 1953-06-07 | 2 | 42°50'N / 94°42'W | 43°00'N / 94°28'W | 16.20 Miles | 833 Yards | 0 | 0 | 0K | 0 | Pocahontas |
| 36.6 | 1991-04-26 | 3 | 42°01'N / 95°21'W | 42°13'N / 95°12'W | 1.70 Miles | 150 Yards | 0 | 0 | 2.5M | 0 | Crawford |
| 36.8 | 2004-06-11 | 2 | 43°08'N / 95°23'W | 43°12'N / 95°18'W | 5.50 Miles | 200 Yards | 0 | 0 | 500K | 0 | Clay |
| Brief Description: A tornado destroyed a hog barn, killing ten hogs, destroyed a greenhouse, destroyed a barn, outbuildings, a machine shed and a garage, and damaged several other farm structures including a horse barn. Several horses were injured. At least two houses were damaged, with windows blown out. Several vehicles were also damaged. Numerous power lines and trees were blown down. The tornado also damaged crops. | |||||||||||
| 37.0 | 1953-06-07 | 3 | 42°33'N / 94°42'W | 42°51'N / 94°15'W | 30.70 Miles | 200 Yards | 0 | 0 | 0K | 0 | Calhoun |
| 37.6 | 1969-07-26 | 2 | 42°07'N / 95°19'W | 42°05'N / 95°06'W | 11.10 Miles | 33 Yards | 0 | 0 | 250K | 0 | Crawford |
| 38.6 | 1964-05-05 | 3 | 42°34'N / 96°21'W | 43°11'N / 95°26'W | 62.90 Miles | 300 Yards | 0 | 0 | 2.5M | 0 | Plymouth |
| 39.0 | 1999-05-16 | 2 | 42°08'N / 95°41'W | 42°07'N / 95°19'W | 16.00 Miles | 80 Yards | 0 | 0 | 500K | 0 | Crawford |
| Brief Description: As was mentioned above, the weather pattern was very active over the central U.S. A cold front had become stationary to the west of Iowa during the afternoon of the 16th. This set the stage for a serious weather situation. During the afternoon, 70 degree F. surface dew point temperatures were widespread for the first time of the season. The airmass became very unstable as the upper levels were still relatively cool. CAPE values during the few hours just prior to the development of the thunderstorms were in excess of 5000 J/kg. The situation became explosive as thunderstorms formed along and just ahead of the cold front over western Iowa. A little later in the afternoon, thunderstorms formed over northeast Iowa along the nose of the low level jet and just north of the surface warm front. These two features combined to produce a variety of severe weather across much of Iowa. The first of the severe weather broke out over west central Iowa. This was on the form of tornadoes. The strongest tornado in the Des Moines CWA touched down in Crawford County near Ricketts. The tornado was F2 strength and caused damage to 10 farmsteads along the way. One farmstead reported the house as being destroyed. The tornado had a duel structure with the two tornadoes about 2.5 miles apart north and west of Ricketts. This tornado was on the ground from near the western county line to a point north of Deloit. This was by far the strongest tornado in the CWA. There were several brief touchdowns and one that was on the ground for a couple miles, west of Denison. During the late afternoon and early evening hours, there were several reports of brief touchdowns from west central into central Iowa. One tornado touched down briefly in Audubon County, another southeast of Bedford in Taylor County destroyed a trailer there and tore a roof off of a shed. Another tornado touched down briefly in rural areas west of Perry in Dallas County. The tornado did little damage however. The same storm knocked down power lines and trees south of Perry as winds were recorded at around 70 MPH a short time later. The final touchdown was brief near Ames, in Story County. There were a few reports of high winds as the line in western Iowa transformed into more of a bow echo structure. A 67 MPH wind gust was recorded at the Creston Airport in Union County. As the storms moved across Dallas County, winds of around 65 MPH blew trees down on a commercial chicken house, killing 5000 laying hens. Winds gusted to 61 MPH at both the NWS office in Johnston and at nearby Ankeny, both in Polk County. As the bow echo continued to move north and east, winds around 65 MPH swept through the Marshalltown area. Damage was reported at a trailer court there as the skirting on some of the trailers was torn off and one of the trailer houses was nearly blown off its supports. The line of storms and high winds made its way northeast into the Wellsburg area of Grundy County, causing extensive damage on a farmstead just southeast of the town. Hail was widespread with all of the thunderstorms as they moved across the state. Many areas reported hail nearly dime size. Reports of hail of up to an inch were quite common as well. Some of the larger hail reports included golf ball size hail in Cass County at Atlantic and baseball size hail reported at both Boone in Boone County and south of Plainfield in Bremer County. Once the severe weather started to wind down, flash flooding was a fairly widespread problem, especially near the warm front over that was over northeast Iowa. The storms associated with the cold front produced flash flooding in Cass County at both Atlantic and Griswold. For the most part, the storms with the cold front were moving too quickly to cause much in the way of flooding, though urban flooding was reported in some areas. The big flooding was over the northeast part of the state. Those areas were hit twice with heavy rain and severe weather, once in the morning and once with this event. Widespread flash flooding took place in Black Hawk, Bremer, Butler, and Hardin Counties. Rains of 4 to 6 inches for the day were common in these areas, as well as areas to the northeast of that. Governor Vilsack declared 12 Iowa counties disaster areas. Butler, Bremer and Black Hawk Counties in the Des Moines CWA were declared disaster areas. All of these same counties were later declared Presidential Disaster Areas. Some of the more serious damage in the Central Iowa CWA was in Black Hawk and Bremer Counties. In Black Hawk County, U.S. Highway 218 was closed for a time by flooded water. The Cedar River caused considerable flooding in the area. The town of Dunkerton was approximately 50% evacuated as waters rose. The Sewage plant there was inundated by the high water. There was damage caused to many public roadways around the county. Some of the bridges over smaller creeks were declared unsafe. The County Engineer stated damages in Black Hawk County were at least $1,200,000, including $560,000 in damage to ditches, roads, culverts, and bridges. Damage in the town of Dunkerton were placed at $500,000 to public infrastructure. The county also reported $183,000 in damages to parks. In Bremer County, numerous homes in the town of Tripoli reported sewer backups into the basements. In the town of Denver, 25 homes reported at least 6 feet of water in the basement. Of those 25 homes, five of them had basement wall damage. Fifteen business in the town had anywhere from 2 inches to 8 feet of water in the basement. Bremer County reported damages to 19 culvert sites, 55 road sites, 2 bridge abutments, and 8 driveway washouts. Damage from these items alone were at least $200,000. In Butler County the county Engineer reported 20 to 30 sites affected with estimated damage of $150,000. One Bridge sustained at least $60,000 damage. Needless to say, numerous county and state roads were under water and closed as well throughout the area. The flooding in these areas was described as worse than the flooding in 1993. In many areas it was worse than the record floods of 1968. Farther to the southwest flash flooding also occurred in Cass County. Damage was not as serious there as the amount of rainfall was not as great. One basement was completely flooded in the town of Griswold. Flooding was serious enough in Atlantic to not only flood several homes but also buckle the pavement on one of the streets in town. | |||||||||||
| 39.0 | 2004-05-21 | 2 | 42°49'N / 94°31'W | 42°49'N / 94°25'W | 5.00 Miles | 500 Yards | 0 | 0 | 25K | 5K | Pocahontas |
| Brief Description: Tornado touched down in open areas east of Rolfe. It did some damage but didn't do significant damage before crossing into Humboldt County. A very unstable airmass was over Iowa and helped kick off the seasons first severe weather outbreak. At the surface a warm frontal boundary extended nearly east to west across the state and provided the focus for thunderstorm development. By the late afternoon, lifted indices were approaching -10 C. with CAPE values around 5000 J/kg over western Iowa. Surface temperatures warmed into the upper 80s with dew points in the low to mid 70s. A southwest surface wind of 15 to 25 kts pushed over the front. Northeast of the frontal boundary winds were easterly around 10 to 15 kts. Actually, the surface boundary was further enhanced by outflow from convective complexes during the day, further sharpening the contrast. Thunderstorms continued to fire along and north of the boundary through the afternoon and into the evening. This resulted in widespread flash flooding as very heavy rains fell on areas that had had significant rainfall the previous night. There were reports in north central into northeast Iowa of 2 to 4 inches of rainfall in a little more than an hours time. Major flooding took place in the Mason City area where evacuations were taking place. The thunderstorms became most intense during the afternoon into the early evening. There were several tornadoes across northeast into north central Iowa. Most were relatively brief touchdowns and were in open areas. Reports of multi-vortex tornadoes were received from Grundy County. The days most significant tornado touched down in Pocahontas County east of Rolfe and tracked into Humboldt County through the Bradgate area. The tornado damaged or destroyed over 75% of the town of Bradgate (pop 120). Tornado damage in Bradgate was very extensive impacting most of the town. Hardly a building was not impacted. Outbuildings, light structures and garages were heavily damaged or destroyed. Two homes were destroyed. Several homes were damaged ranging from minor to extensive. The Survey Team found that the majority of the damage was F1, with a few cases of F2 damage. The F2 damage was to the snapping of very large trees just west of town and the structural damage to two buildings. Nearly all of the 53 homes there reported damage with several totally destroyed. Significant widespread property damage was reported in the tornadoes path. There were several injuries in the town, the most significant being a broken leg. A police officer was reportedly hit by debris from the tornado and suffered a broken leg. According to law officials, the damage path of the tornado was 2 miles wide and about 8 miles long. Storm chasers on the scene reported the tornado itself to be one half mile wide at one point. Reports of hail were numerous through the afternoon and evening. Most of the hail was in the three quarter inch to one inch diameter range. There were a few reports of golf ball size hail from the stronger storms. Winds were not a major problem with the activity. There were spotty reports of winds to around 60 MPH, but most reports were in the 40 to 50 MPH range. One of the stronger wind reports was a 64 MPH wind gust in Tripoli in Bremer County. This gust was measured by a mesonet station there. During the mid evening hours, thunderstorms rumbled across Grundy County. Lightning struck the Sheriff's office there and destroyed a significant amount of office equipment. Damage was reported around $100,000. | |||||||||||
| 39.1 | 1968-04-03 | 2 | 42°59'N / 95°49'W | 0.50 Mile | 100 Yards | 0 | 0 | 25K | 0 | O'brien | |
| 39.5 | 1959-05-28 | 2 | 43°12'N / 95°01'W | 1.00 Mile | 150 Yards | 0 | 0 | 3K | 0 | Clay | |
| 40.7 | 1959-05-28 | 2 | 43°10'N / 94°54'W | 43°12'N / 94°51'W | 2.30 Miles | 100 Yards | 0 | 0 | 25K | 0 | Palo Alto |
| 40.8 | 1970-07-14 | 2 | 42°36'N / 96°00'W | 1.00 Mile | 100 Yards | 0 | 0 | 25K | 0 | Plymouth | |
| 42.2 | 1965-09-07 | 2 | 42°02'N / 95°10'W | 1.00 Mile | 100 Yards | 0 | 0 | 25K | 0 | Crawford | |
| 42.4 | 1976-06-14 | 2 | 43°09'N / 94°54'W | 43°15'N / 94°47'W | 8.60 Miles | 33 Yards | 0 | 0 | 3K | 0 | Palo Alto |
| 42.8 | 1969-06-28 | 2 | 42°00'N / 95°12'W | 42°03'N / 95°08'W | 4.30 Miles | 200 Yards | 0 | 0 | 250K | 0 | Crawford |
| 43.0 | 1991-04-26 | 2 | 43°16'N / 95°14'W | 18.00 Miles | 60 Yards | 0 | 0 | 250K | 0 | Dickinson | |
| 43.2 | 2004-05-21 | 2 | 42°48'N / 94°26'W | 42°48'N / 94°19'W | 7.50 Miles | 880 Yards | 0 | 15 | 2.5M | 10K | Humboldt |
| Brief Description: Tornado intensified as it approached Bradgate. Seventy five percent of the town was damaged or destroyed by the tornado which was one half mile wide as it moved through. A very unstable airmass was over Iowa and helped kick off the seasons first severe weather outbreak. At the surface a warm frontal boundary extended nearly east to west across the state and provided the focus for thunderstorm development. By the late afternoon, lifted indices were approaching -10 C. with CAPE values around 5000 J/kg over western Iowa. Surface temperatures warmed into the upper 80s with dew points in the low to mid 70s. A southwest surface wind of 15 to 25 kts pushed over the front. Northeast of the frontal boundary winds were easterly around 10 to 15 kts. Actually, the surface boundary was further enhanced by outflow from convective complexes during the day, further sharpening the contrast. Thunderstorms continued to fire along and north of the boundary through the afternoon and into the evening. This resulted in widespread flash flooding as very heavy rains fell on areas that had had significant rainfall the previous night. There were reports in north central into northeast Iowa of 2 to 4 inches of rainfall in a little more than an hours time. Major flooding took place in the Mason City area where evacuations were taking place. The thunderstorms became most intense during the afternoon into the early evening. There were several tornadoes across northeast into north central Iowa. Most were relatively brief touchdowns and were in open areas. Reports of multi-vortex tornadoes were received from Grundy County. The days most significant tornado touched down in Pocahontas County east of Rolfe and tracked into Humboldt County through the Bradgate area. The tornado damaged or destroyed over 75% of the town of Bradgate (pop 120). Tornado damage in Bradgate was very extensive impacting most of the town. Hardly a building was not impacted. Outbuildings, light structures and garages were heavily damaged or destroyed. Two homes were destroyed. Several homes were damaged ranging from minor to extensive. The Survey Team found that the majority of the damage was F1, with a few cases of F2 damage. The F2 damage was to the snapping of very large trees just west of town and the structural damage to two buildings. Nearly all of the 53 homes there reported damage with several totally destroyed. Significant widespread property damage was reported in the tornadoes path. There were several injuries in the town, the most significant being a broken leg. A police officer was reportedly hit by debris from the tornado and suffered a broken leg. According to law officials, the damage path of the tornado was 2 miles wide and about 8 miles long. Storm chasers on the scene reported the tornado itself to be one half mile wide at one point. Reports of hail were numerous through the afternoon and evening. Most of the hail was in the three quarter inch to one inch diameter range. There were a few reports of golf ball size hail from the stronger storms. Winds were not a major problem with the activity. There were spotty reports of winds to around 60 MPH, but most reports were in the 40 to 50 MPH range. One of the stronger wind reports was a 64 MPH wind gust in Tripoli in Bremer County. This gust was measured by a mesonet station there. During the mid evening hours, thunderstorms rumbled across Grundy County. Lightning struck the Sheriff's office there and destroyed a significant amount of office equipment. Damage was reported around $100,000. | |||||||||||
| 43.3 | 1972-06-07 | 2 | 42°04'N / 94°52'W | 1.00 Mile | 200 Yards | 0 | 0 | 25K | 0 | Carroll | |
| 45.0 | 1973-06-18 | 2 | 42°28'N / 96°03'W | 1.00 Mile | 300 Yards | 0 | 5 | 250K | 0 | Woodbury | |
| 45.3 | 1979-08-08 | 2 | 43°04'N / 95°53'W | 0.40 Mile | 100 Yards | 0 | 0 | 2.5M | 0 | Sioux | |
| 45.5 | 1954-05-27 | 2 | 42°49'N / 96°05'W | 42°51'N / 96°02'W | 2.30 Miles | 200 Yards | 0 | 0 | 25K | 0 | Plymouth |
| 45.5 | 1973-06-18 | 2 | 42°29'N / 96°04'W | 2.00 Miles | 400 Yards | 2 | 10 | 250K | 0 | Woodbury | |
| 45.7 | 1964-05-08 | 3 | 42°47'N / 96°10'W | 42°49'N / 95°59'W | 9.30 Miles | 200 Yards | 0 | 0 | 25K | 0 | Plymouth |
| 46.4 | 1976-08-11 | 2 | 42°04'N / 94°44'W | 2.00 Miles | 100 Yards | 0 | 0 | 25K | 0 | Carroll | |
| 47.1 | 1965-05-05 | 4 | 42°18'N / 94°28'W | 42°22'N / 94°17'W | 9.90 Miles | 200 Yards | 0 | 0 | 25K | 0 | Calhoun |
| 47.7 | 1983-09-05 | 2 | 42°23'N / 96°04'W | 2.50 Miles | 127 Yards | 0 | 0 | 250K | 0 | Woodbury | |
| 48.3 | 1980-07-19 | 2 | 43°01'N / 94°25'W | 43°02'N / 94°23'W | 0 | 0 | 2.5M | 0 | Kossuth | ||
| 49.3 | 1965-05-05 | 2 | 43°10'N / 95°29'W | 43°24'N / 95°47'W | 21.80 Miles | 33 Yards | 0 | 0 | 3K | 0 | O'brien |
| 49.3 | 1995-05-27 | 2 | 41°52'N / 94°49'W | 42°09'N / 94°42'W | 22.50 Miles | 100 Yards | 0 | 0 | 300K | 6K | Carroll |
| 49.3 | 1967-04-30 | 2 | 43°07'N / 94°40'W | 43°18'N / 94°32'W | 14.00 Miles | 300 Yards | 0 | 0 | 250K | 0 | Palo Alto |
| 49.7 | 1965-09-09 | 2 | 42°03'N / 95°54'W | 42°07'N / 95°43'W | 10.20 Miles | 100 Yards | 0 | 0 | 250K | 0 | Monona |
| 50.0 | 1981-06-13 | 2 | 43°10'N / 95°53'W | 0 | 0 | 3K | 0 | Sioux | |||
* 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.