The Storm Prediction Center has issued a Severe Thunderstorm Watch effective until 6am Saturday morning for the following counties, Harrison, Mills, Monona, Montgomery, Pottawattamie, Shelby, Adair, Adams, Audubon, Boone, Carroll, Cass, Clarke, Crawford, Dallas, Greene, Guthrie, Madison, Polk, Story, Union and Warren. Thunderstorms have begun to develop along a cold front that is currently moving through Iowa into eastern Nebraska late this evening. The main threats from any of these storms will be from large hail and damaging straightline winds.