NEW : CNN 's Dave Hennen , Dave Alsup and Todd Borek contributed to this report . Multiple possible tornadoes are reported across several states . NEW : Iowa 's governor declares a disaster in one county . NEW : Forecasters warn that heavy rains could cause flash flooding . Baseball - sized hail pelts much of Nebraska as a storm moves in .
NEW : Multiple possible tornadoes are reported across several states . NEW : Iowa 's governor declares a disaster in one county . NEW : Forecasters warn that heavy rains could cause flash flooding . Baseball - sized hail pelts much of Nebraska as a storm moves in .