A severe thunderstorm watch is in effect for several west and northwest Iowa counties until 2 a.m. Wednesday. These include Adubon, Buena Vista, Calhoun, Carroll, Cherokee, Clay, Crawford, Greene, Guthrie, Harrison, Ida, Lyon, Monona, O'Brien, Osceola, Plymouth, Pocahontas, Sac, Shelby, Sioux, Webster and Woodbury counties.

A powerful line of storms moved through the Upper Midwest Monday night into Tuesday. The Storm Prediction Center will make the final determination if the system