The National Hurricane Center upgraded a Gulf of Mexico depression to Tropical Storm Lee , the season's 12th named storm of the season.
The slow-moving storm winding its way toward the United States is expected to pack a punch, threatening to drench Gulf coast states with more than a foot of rain over the weekend, hurricane experts said.
Forecasters warned rainfall from 10 to 15 inches over Gulf coast states and a storm surge that could raise water by as much as two to four feet above ground level in some coastal areas.
NHC forecasters issued tropical storm warnings for states from Mississippi to Texas. The center of the storm is likely to approach south Louisiana during the weekend.
Local meteorologists predicted the storm in the Gulf could also lead to a soggy Labor Day weekend for Tampa Bay if it wobbles to the east.
Rains traveling across the peninsula from the east coast seem poised to hit the Tampa Bay area over the holiday weekend, but if the track of the tropical depression changes, so might the area's rain chances.
"Any change in the depression, or what's expected to become a tropical storm, could lead to more rain in the area," said Juli Marquez, Bay News 9 meteorologist. "We're going to be watching for the next couple of days to see what happens."
Meteorologists predict a 40 percent chance of rain Friday. Chances of showers were likely to increase to 50 percent on Saturday and then to 60 percent on Sunday and Monday in the Tampa Bay area.
In the open Atlantic, Hurricane Katia continued to move toward the United States, but poses no immediate threat to any coastal regions, according to the NHC.
Katia, which weakened to tropical storm status from a category 1 hurricane Thursday, picked up speed and became a hurricane again as it moved across warm waters with little wind shear.
Early Friday, Katia was about 750 miles east of the northernmost Leeward Islands and was expected to continue moving west-northwest at about 15 miles per hour.
Its sustained wind speeds Friday topped at about 70 miles per hour.
In what could become the third storm to watch this weekend, a low pressure system about 450 miles south of Halifax Nova Scotia appeared more organized Friday morning, and forecasters predicted a 60 percent chance of it becoming a tropical cyclone by the end of the day.