Florida Governor Rick Scott issued the statement for all 67 counties in his state. Mississippi Governor Phil Bryant approved the deployment of the National Guard, his bureau said in a statement.
Alabama Governor Kay Ivey issued a state of emergency for 40 districts, which will come into effect on Sunday at 6 am, according to a statement from her office. Ivey activates the state emergency operations center in Clanton, the statement said. The Alabama National Guard has also activated their High Water Evacuation Teams.
The first storm this season, Alberto, is likely to intensify as he moves up the Gulf over the weekend, the National Hurricane Center said, bringing heavy rains and potential floods to Florida and much of the Southeast over the next few days. 1
"Swelling from Alberto will generate dangerous surf and rip currents along the Gulf Coast," said the National Weather Service.
The center of the storm is expected to hit near the western tip of Cuba on Saturday afternoon and then track down the eastern Gulf of Mexico during the night until Monday.
The city of New Orleans urged residents and businesses to "prepare and stay abreast of the storm". The main danger is heavy rainfall, which could lead to floods, the city said, but also strong winds and storm surges could cause problems.
"I encourage everyone to be safe and stay informed," Mayor LaToya Cantrell said in a statement.
The hurricane season officially starts on June 1st, but Alberto seems to have missed the memo. The tropical system became a subtropical storm on Friday, the hurricane center said. As it travels along the warm waters of the Gulf, it could become a full tropical storm.
Starting at 11 pm ET Saturday, parts of Cuba and the Florida Keys were under a tropical storm warning, and a tropical storm clock is in effect for parts of Florida, Georgia and Louisiana, meaning conditions for a full storm are likely in the next 48 hours.
CNN's Brandon Miller, Amir Vera and Anne Claire Stapleton contributed to this report.