The Storm Prediction Center has issued a Severe Thunderstorm Watch effective until 10am this morning for the following counties, Adair, Audubon, Black Hawk, Boone, Calhoun, Carroll, Cass, Crawford, Dallas, Greene, Grundy, Guthrie, Hamilton, Hardin, Harrison, Jasper, Madison, Mahaska, Marion, Marshall, Mills, Monona, Montgomery, Polk, Pottawattamie, Poweshiek, Sac, Shelby, Story, Tama, Warren and Webster. Thunderstorms currently over eastern Nebraska and western Iowa will continue to maintain their strength through the morning hours as they move to the east. Large hail and some isolated strong winds will be the main threats with these storms as they traverse the state. Some heavy rainfall is possible as well which may lead to some localized flooding in some locations.