The National Weather Service issued a Tropical Storm Warning at 5 p.m. Saturday for parts of the Tampa Bay area, as Subtropical Storm Alberto continues to travel into the Gulf of Mexico.
The National Weather Service Office in Ruskin advisory said the warnings were expanding north on Florida's west coast and now include coastal Charlotte, Hillsborough, Manatee, Sarasota and Pinellas Counties.
Jeff Huffman, meteorologist for the Florida Public Radio Emergency Network, said the coastal hazards associated with Alberto, namely high surf, coastal flooding, and minor surge will begin to affect portions of southwest Florida Saturday night. The bad weather will be moving up the coast to west-central sections of the state on Sunday.
Water spouts and an isolated tornado are also possible in the stronger rain squalls Sunday, as low-level spin increases on Alberto’s eastern side, he said.
All day Saturday, the National Hurricane Center continued to describe Alberto as “not very well organized,” but warned that “more significant strengthening” may occur Saturday night and Sunday. The forecast track continues nudging slightly east, with landfall expected Monday night just west of Pensacola.
Earlier Saturday, a Tropical Storm Watch had been issued and Gov. Rick Scott declared a state of emergency for the entire state just before 11 a.m.
At a briefing at the state emergency operations center in Tallahassee, authorities urged Floridians to take the storm seriously. Wes Maul, the state's emergency management director, said timing of the storm is uncertain, but the entire state will feel the effects. Swelling riverbanks, tornadoes and localized flooding are possible.
As a result, the Tampa Bay area and the southern third of the state continue to see a steady, sometimes moderate rain. A flood watch issued Friday continues for areas along and south of the Interstate 4 corridor.
Jeff Huffman, meteorologist for the Florida Public Radio Emergency Network, said Subtropical Storm Alberto could produce tropical storm force winds, minor storm surge, and inland flooding along portions of the Florida Gulf Coast on Sunday and Monday.
“We're looking for high surf, high winds gusting to 30-35 mph, and high risk of rip currents,” Huffman said.
Locations near Pensacola to Panama City are most likely to experience these conditions, but the potential hazards from this storm also include coastal regions as far south as Naples, he said.
“This one is likely to have a very large circulation, and it has connections deep in the tropics,” Huffman said. “So the heavy rain and potential flood risk is there for really the entire state. And keep in mind, it's forecast to almost stall Monday and Tuesday, so the moisture could keep moving in for days."
The heaviest rain is likely to move into the Tampa Bay area by Sunday morning and continue through Monday afternoon, Huffman said. Strong thunderstorms are also possible every afternoon and evening through Wednesday, he said.
Early rainfall projections through Monday are between 2 and 4 inches, but much higher totals could occur depending on the eventual track of the storm. This could lead to localized urban flooding in low-lying areas. River flooding is also possible in the days following the event.
Breezy conditions and waterspouts are possible along the coast, with a few isolated tornadoes possible across interior sections, Huffman said.
Subtropical Storm Alberto - the first named storm of the 2018 hurricane season - roiled parts of coastal Mexico and Cuba with rip currents and dangerous surf before plodding northward Saturday.
Cuba maintained its tropical storm watch for the province of Pinar del Rio, while Mexico cancelled its watch for the resort-dotted coast of the Yucatan peninsula, where the storm brought heavy rain. There were no immediate reports of emergencies. In Cancun, local newspapers showed scenes of some streets flooded to mid-hubcap level.
In the U.S., a storm surge watch - meaning the possibility of life-threatening inundations from rising coastal waters moving inland - was issued for a stretch of coastline between Horseshoe Beach in the Big Bend Region, and the mouth of the Mississippi River.
"The combination of storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline," the National Hurricane Center in Miami said. Isolated tornadoes could erupt over the Florida Keys or southwestern Florida late Saturday.
Forecasters at the National Weather Service warned residents along coastal Alabama and Mississippi as well as the Florida Panhandle to brace for heavy rain and high winds. Isolated tornadoes were also possible. The NWS said a flash flood watch would be in effect from Saturday evening through Tuesday evening for southeastern Mississippi, much of southern Alabama, and the western Florida Panhandle.
"This system will bring excessive rainfall to the watch area beginning Saturday evening and continuing through Tuesday evening. Rainfall amounts of 5 to 8 inches, and possibly locally up to double these amounts are possible in this area with this event," the NWS said.
At 8 a.m. EDT, the National Hurricane Center in Miami said Alberto was centered about 70 miles (115 kilometers) south of the western tip of Cuba and moving north at 9 mph (15 kph). Its top sustained winds were 40 mph (65 kph). A gradual strengthening was expected as the storm moves north.
A subtropical storm has a less defined and cooler center than a tropical storm, and its strongest winds are found farther from its center. Subtropical storms can develop into tropical storms, which in turn can strengthen into hurricanes. Alberto comes ahead of schedule: the six-month hurricane season doesn't begin until June 1.
Parts of Florida, Georgia, Alabama, Mississippi and Louisiana have already seen heavy rain this week, and further deluges could leave those areas vulnerable to flash flooding and river flooding. Some beachfront and riverfront communities are already handing out sandbags.
The downpours could dampen Memorial Day, the unofficial start of the summer tourist season along Gulf beaches. Along with heavy rains and high winds come rough seas and a threat of rip currents from Florida to Louisiana that can sweep swimmers out to sea.