Tornado and Damaging Winds in Iowa, August 3, 1994

Thunderstorms were numerous over Iowa throughout the day. Several weather features caused the continual development. There was an upper level disturbance approaching from the west, while a trough of low pressure approached from the northwest. Farther northwest was an approaching arctic cold front. The atmosphere was very moist with deep moisture in place and convective available potential energy between 3000 and 3500 J-Kg-1 over much of the state. Even so, the situation was not overly conducive to severe weather. Thunderstorms moved over the west half of the state during the morning hours. The east half remained under partly sunny skies with thunderstorms erupting during the early afternoon hours, once the weak cap had broken. The storms produced heavy rainfall and some gusty winds. Only a few became severe. A severe thunderstorm moved through Winfield in Henry County, downing several trees. Another storm produced a brief microburst south of Newton in Jasper County. Many large tree limbs, up to 20 inches in diameter, were torn off. Crops were flattened in a narrow strip for about a mile downstream. Another storm produced a brief spin up tornado in Benton County. The tornado was observed by a boater as it touched down on Rogers Park Lake. It sucked up water briefly before breaking apart. One could call it a waterspout since it did occur over water, however meteorologically it had thunderstorm structure of a land event. For that reason it was listed as a tornado instead of a waterspout. During the morning, thunderstorms moved through Clarion. Lightning struck the chimney of the elementary school. Several blocks were knocked out of the top of it and the chimney was cracked all the way down to its junction with the main building.