Iowa Environment & Hazard Risk

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.

Widespread straight-line winds that produced extensive damage were reported throughout Linn County, associated with a derecho. These winds lasted around an hour in total at any one location, even though the initial line of storms moved out quickly. Damaging straight-line winds continued and were associated with the rear inflow jet. Maximum wind speeds were estimated to be 80 to 100 MPH for much of the county, with areas in central Linn County that had wind speed estimates that were 120 MPH or higher. The highest estimated wind speed were in the Cedar Rapids area where extensive damage to an apartment complex occurred with damage indicating winds about 140 MPH. A radio transmission tower also collapsed with wind speed estimated at 130 MPH. These estimates were determined based off damage reports and photos submitted through social media as well as a damage survey. The peak thunderstorm wind gust measured at the Cedar Rapids airport ASOS before it lost power was 68 MPH. The duration of strong winds caused extensive damaged most if not all trees, crops, and structures in their path. Due to the widespread damage, long duration power outages occurred. One fatality occurred here when...

This is the first segment of this devastating tornado which passed through four counties including Madison, Warren, Polk and Jasper. The tornado began northwest of Macksburg in western Madision county. The tornado remained in mostly rural cropland and wooded areas of western Madison county. The tornado passed through Pammel State Park southwest of Winterset producing extensive tree damage as the tornado continued to widen into a wedge tornado. Upon exiting the park, the tornado travelled along Carver Road. Several residential homes were extensively damaged or destroyed along Carver Road and six deaths occurred along this stretch of road. The tornado was at peak intensity at this time with EF4 damage occurring west of the intersection of Carver Road and Highway 169 with a house completely destoyed and removed from the foundation. After departing the Carver Road corridor, the tornado progressed just southeast of Winterset and eventually passed east of town and crossing State Highway 92. Damage in these areas was primarily to trees and outbuildings although a few homes were also impacted with mostly EF1 to EF2 damage. From Highway 92 to where the tornado exited the...

Tornado developed about 3 miles north of Pella and moved southeast for its entire length. The tornado initially remained in rural areas just north and northeast of the town producing crop, tree and minor structural damage to houses. The tornado began to intensify just northeast of town and shifted a house off of its foundation. The tornado then encountered the Vermeer facility on the east side of town producing EF3 damage to one of the large buildings along with tossing numerous cars about the facility. 13 injuries occurred at the Vermeer facility with 6 requiring transport to the hospital. The tornado then turned slightly eastward before passing into Mahaska county.

This large and violent tornado entered into south central Adair County from Adams County. The tornado remained a multi-vortex circulation as it moved into the county producing high end damage for much of its remaining path. The tornado encountered several houses in the vicinity of Fontanelle Road and 320th Street. Many of the structures received at least EF2 damage with one house north of the intersection receiving up to EF4 damage with a sufficiently anchored structure destroyed and slumped into a debris field nearby. Additional EF4 damage was noted at a farmstead on Jordan Avenue south of 280th Street with the house destroyed and trees chewed down to only the largest trucks and portions of the bark removed. The path then passed through another wind mill area with additional turbines collapsing west of Kent Avenue. The tornado then passed over Nodaway Park Ponds and entered the southwest side of Greenfield along SW 3rd Street. Several structures over the next several blocks had up to EF4 damage from SW 3rd Street over the SE 3rd Street and South of Linn Street and north of Oak and Noble Streets. Most of these saw complete destruction of the house with much of the...

Flooding continued on the Missouri River due to snow melt in the Dakotas and over the Northern Rockies, a few episodes of rain, and increased discharges from dams on the Missouri River over the Dakotas. In addition flooding continued due to levee breaks on the river. Towns that continued to have flooding included Bartlett, McPaul, Thurman, Percival and Hamburg. Interstate 29 remained closed with water over the road through much of the county. Iowa Highway 2 was also under water and suffered extreme damage. Businesses just west of Interstate 29 on Highway 2 were also under water.