Tropical Storm Fred forms in Caribbean as South Florida remains on edge of forecast path

Tropical Storm Fred finally formed Tuesday night and held to a course that could take it to Florida this weekend.

The first new tropical cyclone in more than a month achieved a top wind speed of 40 mph, just above the threshold for a tropical storm, the National Hurricane Center said in its 11 p.m. update. It is forecast to weaken as it passes over the mountainous islands of the northern Caribbean Sea and then strengthen again as it approaches Florida or the Gulf of Mexico at the end of the week.

The map of possible paths for the storm’s center moved South Florida from the center to the right edge of the cone of uncertainty. The cone now shows a greater chance the storm will head into the Gulf of Mexico. But forecasters said there’s considerable uncertainty about its long-term course.

If the storm does approach South Florida, wind and rain should pick up late Friday evening and into Saturday, according to the National Weather Service. South Florida has a 6% to 10% chance of experiencing tropical storm-force winds, which means winds of at least 39 mph.

Forecasters said projections of the storm’s path are unusually uncertain because it lacked a well-defined center, making its course harder to predict as it heads across the islands of the northern Caribbean Sea.

Meanwhile, a new cluster of thunderstorms was noted Tuesday afternoon off the African coast. Following roughly the same path of the current storm, it has a 30% chance of organizing itself into a tropical cyclone, the catch-all term for closed-circulation storms that range in strength from depression to hurricane.

Fred is expected to move near or over the U.S. Virgin Islands and Puerto Rico before nearing or passing over Haiti and the Dominican Republic on Wednesday, the National Hurricane Center said.

The exact track and strength of the system is less certain midweek due to changing wind shear and steering breezes, AccuWeather forecasters said. Tropical-storm-force winds extend outward up to 45 miles from the center.

The storm is expected to temporarily weaken as it passes over the mountainous terrain of Haiti and the Dominican Republic. But once it clears the islands of the Caribbean, it will have the potential to regain strength.

South Florida could be affected by heavy rain and flooding later this week and into the weekend, according to the National Weather Service.

There’s always a good chance of rain in South Florida during the summer, but that chance increases to about 70% in areas south of Lake Okeechobee and north of the Florida Keys likely by Friday afternoon, said National Weather Service meteorologist Paxton Fell.

Tropical storm warnings and watches were in effect Tuesday for Puerto Rico, the U.S. Virgin Islands, the Dominican Republic, Haiti, southeast Barbados and surroundings areas.

Eastern and southeastern portions of Puerto Rico have the highest chance for potential flooding, according to the National Hurricane Center.

Forecasters say swells could cause life-threatening surf and rip current conditions across the U.S. Virgin Islands and Puerto Rico through morning and then Haiti and the Dominican Republic later in the day.

Robert Frye, senior meteorologist for the National Weather Service, said there are mitigating factors that could hinder the system’s development on its approach toward Florida.

Warm water temperatures and low wind shear over the next day or so will create conditions favorable for storm development. However, dry air is expected after that, which would be a hindrance.

“At this point it’s way too early to know the specifics in terms of telling how strong the system will be,” Frye said.

“Right now the forecast is generally west-northwest toward our area by some time late into the week, and the weekend, especially,” he said.

Tropical Storm Fred is the first tropical cyclone to form in the Atlantic in more than a month, since the July 1 appearance of the storm system that would become Hurricane Elsa.

The number of storms is likely to increase in frequency over the next few weeks as the season ramps up toward its September peak. The next storm name after Fred is Grace.

Sun Sentinel staff writers Eileen Kelley and Angie DiMichele contributed to this report.