Hail and Damaging Winds in Iowa, October 22, 2001

The cold front that had become stationary just south of Iowa on the 21st began to lift north as a warm front during the day on the 22nd. A strong push of moist air too place by the early afternoon hours. Dew point temperatures over the south one to two tiers of counties reached into the low 60s. Thunderstorms developed in the warm air advection just north of the front. As the afternoon progressed, upper level wind speeds increased to between 60 and 70 kts. Thunderstorms formed over southeast Nebraska and moved east into southwest Iowa. Though there was a fairly large area of thunderstorms, the strongest storms formed close to the warm front on the cold side of it. As the thunderstorms evolved, it was clearly evident on the WSR-88D that a mesoscale convective vorticity maximum had developed with the stronger storms. The system continually evolved as the main cluster of thunderstorms moved east-southeast, parallel to the warm front. At several points during the event, the echos took on a bow echo formation. Winds were generally not a major factor with this event as the storms themselves were elevated. High were not able to mix down to the ground except at a few locations. Many locations reported wind gusts of 30 to 40 MPH, but the only area were severe winds were reported were in Clarke County and in the area from Monroe into Wapello Counties. Seventy MPH winds blew down a barn near Osceola in Clarke County. Sixty MPH winds buffeted the area from Chariton into the Ottumwa area. The storms were significant hail producers. Most of the non-severe thunderstorms produced pea to marble size hail. The severe cluster produced copious amounts of three quarter to one and one three quarter inch diameter hail. Many locations reported hail accumulations of one to two inches. The hail fell at a bad time for the soy bean crop. Much of the crop was mature and there were several reports of pod breakage due to the hail. Two and one half inch diameter hail pelted areas north of Russell in Lucas County. Many windows were broken out by the hail, which was the largest of the afternoon. Golf ball size hail caused considerable damage in Adair County southwest of Orient. Reports indicate the hail broke numerous windows out of houses in the area. As the storms moved through the Osceola area of Clarke County, golf ball size hail broke out numerous double pane windows in houses east of town. Farther east, hail broke windshields in several cars in Monroe County at Albia. Once the cluster of severe thunderstorms moved east of the Des Moines CWA, additional thunderstorms continued but there were no additional reports of severe weather.