A significant storm system is set to impact millions of people across five U.S. states, prompting the National Weather Service (NWS) to issue flood watches due to anticipated heavy rainfall. The system, which has already brought severe thunderstorms and tornadoes to Oklahoma, is expected to move eastward, affecting the U.S. South and the Great Lakes region. Southeastern Louisiana, Mississippi, northern Alabama, central Tennessee, and parts of Wisconsin are currently under flood watches.