Hail in Iowa, May 7, 1997

A strong weather system moved into the state bringing with it the seasons first push of deep gulf moisture. A warm front pushed into southwest Iowa during the afternoon bring with it surface dew point temperatures in the low to mid 60s. Meanwhile, a cold front was approaching from the west. Convection fired during the morning and rolled southeast across the state. During the early afternoon, dry air moved into southwest Iowa, destabilizing the atmosphere. By early afternoon, CAPE values were near 3000 J/kg, with Lifted Indices near -8 degrees C. The first thunderstorms erupted over west central Iowa. Within 20 minutes the storms became severe. WSR-88D reports showed VIL values in the storm topped 73 Kg/m/m. This storm produced golf ball size hail in the town of Denison. The storms continued to develop into a line during the late afternoon and early evening hours. Most of the hail along the line was smaller, with reports of three quarters to one inch diameter hail received as the storms advanced east. A cluster of thunderstorms develped over central Iowa during the late afternoon. The line from the west merged with this cluster, producing copious amounts of rain over Polk, Warren, and Marion Counties. Reports indicate that 2 to 4 inches was common over much of the area. Far southeast Polk County had about 2 1/2 inches, over 3 inches fell in Indianola of Warren County, with 4 to spotty 5 inch amounts reported over Marion County. Flooding occurred as a result of the heavy rainfall. Much of the flooding was limited to urban flooding, however larger streams flooded ovenight in Warren and Marion Counties as the North and Middle Rivers crested several feet above flood stage. Damage was not very serious however as the flooding that did occur was in areas were it is quite common and there was not much to flood. During the early evening, a lone thunderstorms developed and moved into Madison County. This storm was not long lived, however it did produce golf ball size hail as it passed west of Peru. During the early evening hours, a thunderstorm rolled through Taylor County. As it passed over the city of Lenox, lightning struck the television station there. Damage to the equipment took the station, as well as the city's cable system, off the air for several weeks.