Washington, May 28 (IANS): The US states of Alabama, Florida and Mississippi have declared an emergency ahead of subtropical storm Alberto expected to make landfall on Monday, authorities said.

The storm continued churning north through the Gulf of Mexico on Sunday and is scheduled to make landfall on the Florida Panhandle early Monday morning, reports CNN.

Florida Governor Rick Scott issued the declaration for all 67 counties in his state.

Mississippi Governor Phil Bryant authorised the use of the National Guard, his office said in a statement.

Alabama Governor Kay Ivey issued a state of emergency for 40 counties.

Ivey activated the state's emergency operations centre while the Alabama National Guard activated its high water evacuation teams.

Alberto is expected to produce heavy rainfall and flooding over western Cuba, South Florida and the Florida Keys, the National Hurricane Centre said on Sunday.

"Heavy rains and gusty winds continue to spread northward over Florida," it tweeted.

"Hazardous storm surge is possible along portions of the central and eastern Gulf Coast beginning Sunday."

The first named storm of this season, Alberto is expected to strengthen as it moves up the Gulf this weekend, CNN quoted the Centre as saying, bringing heavy rains and possible floods to Florida and much of the Southeast in the coming days.