A tropical storm warning remained in effect from the mouth of the Suwannee River north of Cedar Key to the Alabama-Mississippi border.
Mandatory evacuations were issued for Franklin County's barrier islands and anybody living on the coastline in mobile homes and recreational vehicle parks.
Though the storm has passed Central Florida without making landfall, rain is expected in the area on Memorial Day, according to the National Weather Service.
It is forecast to drop as much as 30cm (12in) of rain across MS to western Georgia and to bring storm swells of about 60-120cm (2-4ft) to low-lying areas.
In Gulfport, Mississippi, people lined up Sunday to fill 10- and 20-pound bags full of sand to use to block flooding from the storm.
"I'm doing this because every time we have a hard rain, it floods at my house", Whitlock said.
Subtropical Storm Alberto is a little better organized this morning and winds are at 45 miles per hour.
The flow of moisture out of the South is expected to continue, bringing a chance of daytime showers and thunderstorms to the Triangle through the week and into the weekend, Carroll said.
Hawaii street swallowed by 'lava tide' as many more homes burn
Hawaii County Civil Defense said earlier Sunday that lava had reached the Puna Geothermal Venture Plant, covering a well. Hawaiian residents fear an explosive emission of deadly hydrogen sulphide and other gases should wells be ruptured.
Satellite photos (above) show the center of the storm just offshore of the Florida Panhandle, and the very obvious moisture feed from tropics - the tail - extending in a comma shape just offshore of the peninsula and continuing south. "We're talking eight to 12 inches of rain this weekend, and storm surges on the Gulf Coast".
Florida, Alabama and MS launched emergency preparations on Saturday.
Little change in strength is forecast before Alberto reaches the northern Gulf Coast.
Alberto is expected to move northward, reaching the Florida panhandle by Monday afternoon, Zouzias said.
A tropical storm warning expired for Cuba's western Pinar del Rio province, where heavy rains could trigger flash floods and mudslides, the National Hurricane Centre said.
Tracey Gasper and her 6-year-old son, Chase, travelled to Biloxi Beach from Donaldsonville, La., for a day of fun in the sun with a group of friends from Baton Rouge, La.
The latter will have the better chance of seeing water rise as at that time we will have a more on shore wind component.
Rain falls on Clearwater Beach by Pier 60 early Sunday morning May 27, 2018, as northbound Subtropical Storm Alberto looms in the gulf to the southwest.as northbound Subtropical Storm Alberto looms in the gulf to the southwest.
Trivia: Although subtropical storms have always been a part of the historical record, they were not officially given names until 2002.