NEW : Severe weather outlook improves for Southeast , mid-Atlantic . Three deaths have been reported in Tennessee . The storms first hit before dawn , with an EF4 killer tornado packing 170 mph winds as it smashed Harrisburg , Illinois , killing six . The National Weather Service has issued a severe thunderstorm watch from the southern tip of Florida to central Georgia and northern Alabama through Saturday morning. Harrisburg , Illinois , is among the hardest hit , with at least six deaths .
NEW : Severe weather outlook improves for Southeast , mid-Atlantic . Three deaths have been reported in Tennessee . The National Weather Service has issued a severe thunderstorm watch from the southern tip of Florida to central Georgia and northern Alabama through Saturday morning. Harrisburg , Illinois , is among the hardest hit , with at least six deaths .