The Storm Prediction Center has issued a Severe Thunderstorm Watch in effect until 4am Saturday morning for the following counties, Benton, Buchanan, Cedar, Clinton, Delaware, Dubuque, Iowa, Jackson, Johnson, Jones, Keokuk, Linn, Washington, Adair, Black Hawk, Boone, Cass, Dallas, Greene, Grundy, Guthrie, Hardin, Jasper, Madison, Mahaska, Marion, Marshall, Polk, Poweshiek, Story, Tama and Warren. Thunderstorms have been firing along the western counties of the state. The storms will be capable of producing large hail and damaging winds. The storms will be moving out of the state by later in the morning.