Hail and Damaging Winds in Iowa, June 4, 1999

A strong southerly flow of air developed over Iowa during the predawn hours setting the stage for the development of a mesoscale convective complex. A warm front was positioned to the southwest of Iowa. To the south of the front, surface dew point temperatures were in the low to mid 70s. To the north they remained around 60 degrees F. A low level jet stream formed with wind speeds in excess of 50 kts. Initially, thunderstorms fired over central Nebraska. After midnight, convection began to fire in a band from northwest into central Iowa. This convection remained below severe levels however. Meanwhile. the convection over Nebraska formed into a full blown mesoscale convective complex and moved into eastern South Dakota and northwest Iowa. After sunrise, the system did not die out as is usually the case. Instead it turned southeast and headed into Iowa. By mid morning, a beta bow element started to slide southeast across the state. The main weather features associated with the bow echo was winds and hail. As the system continued southeast across the state, it took on more characteristics of a derecho, and indeed turned southward and was over southern Alabama by the following morning. Reports of winds of 60 MPH or higher were numerous with the passage of the bow echo. Fortunately, most of the damage was limited to tree and power line damage. At least one home was damaged by high winds in Warren County, west of St. Marys. Reports of hail were also numerous with many reports of one inch up to golf ball size diameter hail. Lucas County was hard hit with hail of one and one half to two inches in diameter. In the town of Chariton, two inch diameter hail nearly covered the ground. The area of storms continued southeast and produced 58 MPH winds in Ottumwa, and 60 MPH winds in northern Davis County. The town of Stiles in Davis County received three quarter inch diameter hail as well. As the storms moved through central Iowa, lightning caused at least two fires. Lightning struck an apartment complex containing six units in Ames, setting it on fire. No injuries were reported, however extensive damage occurred to the complex. In Johnston, lightning struck a home and caused a fire in the attic. Damage there was limited to about $10,000.