Scattered thunderstorms are expected to develop by 4:00 pm CDT along a cold front near the Minnesota and South Dakota border. More storms will gradually develop southward toward the Sioux City area early this evening. Initially these storms will bring a threat of very large hail...up to the size of baseballs...and tornadoes. The storms are then expected to evolve into a line during the evening as they approach Windom, Spencer, and Cherokee. As they form into a line, the tornado threat will lessen. However, the risk of damaging winds will increase. Wind gusts in excess of 70 mph will be possible. In addition, a few storms may produce hail up to the size of ping pong balls. The storms are expected to move east of Spencer and Storm Lake by 10 pm.