Obama on Tuesday ordered "federal aid to supplement state and local response efforts in the area struck by severe storms and flooding," a White House statement said.

The emergency declaration authorizes the Department of Homeland Security and the Federal Emergency Management Agency (FEMA), to coordinate all disaster relief efforts in the state.

"Runoff from the very heavy rainfall of the past two days will continue to flow into area rivers," the National Weather Service said in a flood warning.

"Widespread and potentially severe dangerous flooding... will be occurring through much of the morning," the service said.