Disasters and Emergencies
Severe thunderstorms visit Iowa frequently each year. On average, Iowa sees close to 50 tornadoes, tens of flash flood events, hundreds of severe thunderstorms and thousands of non-severe thunderstorms.
By definition, a severe thunderstorm must contain hail that is one inch in diameter or larger, straight line winds 58 mph or stronger and/or a tornado. The National Weather Service issues severe thunderstorm and tornado watches and warnings for severe thunderstorms.
Storms possessing this structure have been observed to generate the vast majority of long-lived strong and violent (EF2 to EF5) tornadoes, as well as downburst damage and large hail. Supercells are thunderstorms consisting of one quasi-steady to rotating updraft which may exist for several hours.
Know what to do before, during, and after a severe thunderstorm.
Iowa disaster history
2020 August Derecho
A derecho swept across the states of South Dakota, Nebraska, Iowa, Wisconsin, Illinois, Indiana, Michigan, and Ohio on Monday, August 10, 2020, leaving behind widespread and shockingly devastating damage in its wake, hitting central and eastern Iowa the hardest. Millions across the Midwest were affected by wide-scale utility disruptions, residential and commercial property damage, and severe damage to corn and soybean crops. Cedar Rapids was the most severely damaged, suffering a near-complete blackout that lasted for weeks in some areas, widespread and severe property damage, and an estimated loss of at least half of the city’s tree canopy. The derecho caused an estimated $11 billion in damages and spawned a years-long cleanup effort. As of October 2020, it is the most costly thunderstorm in US history.
Video credit: Nick Stewart, Meteorologist and storm chaser for CBS2/Fox 28 news in Cedar Rapids