Power Outage in Marshalltown, IA

Public reported snapped power poles. Time estimated from radar.

Public relayed images of tree and power pole damage. Time estimated from radar.

This tornado developed northwest of Marshalltown west of the little hamlet of Marietta. The tornado traveled southeast on the western side of the Iowa River producing extensive crop and tree damage. The tornado strengthened quickly and took on a wedge appearance as it entered northwest Marshalltown. The tornado tracked more easterly as it entered town producing widespread EF1 and EF2 damage. The tornado went directly through the business district of Marshalltown with EF2 and EF3 damage to many structures including the county courthouse which lost the spire off the clock tower. The tornado continued east through housing areas before encountering the Lennox plant on the east side of town, producing EF3 damage once again. The tornado began to weaken rapidly after this point and dissipated near power plant located on the east side of town. The tornado produced a total of 22 direct injuries. An additional indirect injury resulted during the clean-up of storm debris when a tree fell on a man.

This tornado developed northwest of Marshalltown west of the little hamlet of Marietta. The tornado traveled southeast on the western side of the Iowa River producing extensive crop and tree damage. The tornado strengthened quickly and took on a wedge appearance as it entered northwest Marshalltown. The tornado tracked more easterly as it entered town producing widespread EF1 and EF2 damage. The tornado went directly through the business district of Marshalltown with EF2 and EF3 damage to many structures including the county courthouse which lost the spire off the clock tower. The tornado continued east through housing areas before encountering the Lennox plant on the east side of town, producing EF3 damage once again. The tornado began to weaken rapidly after this point and dissipated near power plant located on the east side of town. The tornado produced a total of 22 direct injuries. An additional indirect injury resulted during the clean-up of storm debris when a tree fell on a man.

Emergency manager reported tree on a large propane tank near Liscomb on Oaks Ave, many trees and power lines down in Marshalltown, traffic lights down in Marshalltown, and a barn down.

A dugout at a school was destroyed by high winds. Power was out through much of the town.

Tree fell and took out a power line near Bangor.

Power poles snapped in half near Highway 30 and the 330 Junction.

Power was knocked out by winds of 65 MPH.

A nearly stationary frontal boundary remained draped east to west across Iowa once again. The atmosphere became very unstable during the afternoon with highs reaching the upper 80s to low 90s and dew points in the mid 70s to the south of the front. The environment at the beginning of the event showed a CAPE of 5000 to 6000 J/kg and lifted indices in the -9 to -12 C. range. The LCL was a little lower than the previous couple days and was around 1000 meters. The environment had a fair amount of shear, in the 35 to 50 kt range. Downdraft CAPE values were quite high with 1200 to 1700 J/kg available. Once again, the freezing level was quite high at around 15,000 feet, so in spite of the hail cape, CAPE in the -10 to -30 C. layer of the atmosphere, being 500 to 800 J/kg the hail size was restricted. Precipitable water values were in the 1.5 to 1.75 inch range. Thunderstorms formed in two areas. An area of thunderstorms formed over north west into north central Iowa. These were ahead of a line of intense thunderstorms that moved in from Nebraska during the early evening. Initially, the storms produced high winds. Winds of 70 to 80 MPH hit Pocahontas County in the Rolfe and Plover areas. Outbuildings and grain bins were blown over in Humboldt County in the Bradgate area, and a downburst occurred in the Worth County at Manley. Downburst winds also hit south of Bode in Humboldt County. High winds snapped off 40 utility poles in the area. There were numerous reports of trees and power lines down in northwest and north central Iowa. Late in the event, a small bow segment dropped southeast across Marshall County and produced a 59 MPH wind gust at the RWIS site there. The main event was the heavy rainfall and flash flooding. Soil conditions were extremely wet with many of the areas across northern Iowa receiving 6 to 12 inches of rain during the past week. The additional rain on the evening of the 21st caused considerable flash flooding. In Humboldt, for example, 5.7 inches of rain fell with the passage of the line. This lead to the evacuation of a care center in Humboldt. There were several reports of 2 to 4 inch rainfalls. The hardest hit counties were Pocahontas and Humboldt with a large area of greater than 4 inches of rain covering these counties. Following the flooding of the past few nights, the Governor Chet Culver gave a flooding disaster proclamation for 5 counties. They were Pocahontas, Palo Alto, Webster, Humboldt, Calhoun and Boone inside of the CWA, and Cherokee just outside of the CWA. School was canceled in many school districts for a good part of the week.

An east to west warm frontal boundary extended from southern Nebraska into extreme southern Iowa. A strong push of warm and unstable air pushed over the top of the boundary. Lifted indices were in the -8 to -11 C range with Cape values of 3000 to 5000 J/kg during the event. Thunderstorms developed over west central and southwest Iowa during the predawn hours. The area spread east and expanded toward sunrise. The initial shot produced a few wind gusts in the central counties to around 60 MPH. Thunderstorms remained below severe limits for a few hours after that. Another area began to become more intense, aided by the cool pool produced by the first round of convection. This area progressed east and south, producing wind gusts of 60 to 65 MPH with the stronger storms. Damage was restricted to tree and power line damage for the most part. Two barns were destroyed in Davis County south of Bloomfield. One cell produced hail toward the end of the event. Hail up to golf ball size fell in the New Virginia area of Warren County. In the area behind the main thunderstorms, development took place in northwest Iowa. The thunderstorms trained over Wayne County for two to three hours. Seven inches of rain fell west of Corydon in that period and caused flash flooding in the area. Ten inches of rain was flowing over the roads following the rain.

A southerly flow of moist and unstable air moved into Iowa during the afternoon of the 9th. A cold front was positioned to the northwest of the state and began moving southeast across South Dakota. As the cold front advanced southeast, thunderstorms erupted over northwest Iowa. As the evening progressed, the storms worked toward the southeast. Most of the severe weather associated with the storms was in the form of hail with only scattered reports of high winds. Hail of three quarter inch to a little over an inch in diameter was common. A few reports of golf ball size hail were received. In Pocahontas County, golf ball size hail pelted the town of Havelock. Later in the evening, golf ball size hail was reported in Tama County in the town of Gladbrook. There were only a couple areas where significant wind damage was reported. In the Atlantic area of Cass County, winds around 70 MPH caused damage with numerous reports of trees down in the area. In Guthrie County, high winds toppled several trees in the Yale area. One of the trees fell into some power lines, knocking out power for a portion of eastern Guthrie County.

The cold front mentioned above continued to move southeast into the state. As the thunderstorms that produced the hail over the northern part of the state during the evening hours weakened and moved east, another round of thunderstorms developed over west central Iowa. The storms produced high winds and hail. They formed into a scattered to broken line with numerous beta bow elements along the line. Initially the storms produced hail of up to an inch in diameter over west central Iowa. The event transformed into a wind event fairly early on. High winds swept into the Marshalltown area of Marshall County. A 195 foot radio tower collapsed in the wind. Considerable damage was reported in the area. Another example of wind damage came from Marion County as 60 to 70 MPH winds toppled trees and power lines in the area. Once again, crop damage was significant due to the condition of the tinder dry crop with reports of lodging received.