Tropical Storm Ernesto could form soon in the Caribbean. Here's what the forecast says

MIAMI — Puerto Rico, the Virgin islands and a dozen other Caribbean islands are now under a tropical storm warning as forecasters monitor a system that is expected to strengthen into Tropical Storm Ernesto.

The future Ernesto is forecast to bring heavy rain, flash flooding and other stormy conditions to Puerto Rico, the Virgin islands and a dozen other islands in the Caribbean this week, forecasters say. Ernesto would be the fifth named storm of the 2024 Atlantic hurricane season.

Forecasters expect the system will turn into a tropical depression Monday as it moves rapidly west across the Atlantic, toward the Caribbean. It’s forecast to turn into a tropical storm by the time it nears islands in the eastern Caribbean Sea late Monday before approaching the U.S. and British Virgin Islands and Puerto Rico, according to the National Hurricane Center.

In a Monday briefing, National Hurricane Center Director Michael Brennan said the system is expected to strengthen into a “powerful hurricane” later this week once it moves away from Puerto Rico and turns north into the western Atlantic’s open waters, toward Bermuda.

Based on Monday’s forecast track the system is not a threat to Florida. Brennan said dangerous surf and rip current conditions will be possible along the U.S. eastern coast this weekend.

Here’s what else to know:

Where is the system now and where is it going?

The system, which is moving quickly west across the Atlantic, was about 375 miles east-southeast of Antigua and about 630 miles east-southeast of San Juan, Puerto Rico, according to the hurricane center.

NOAA’s hurricane hunters found that the disturbance has become better organized with maximum sustained winds near 35 mph with higher gusts although it still lacks a well-defined center, according to the hurricane center.

Forecasters expect it will strengthen into a tropical storm by the time it reaches the northeastern Caribbean Sea islands, with its center to forecast to move over portions of the islands late Monday or early Tuesday.

The forecast shows it remaining at tropical storm strength as it nears or goes over the Virgin islands and Puerto Rico Tuesday evening and into Wednesday.

Brennan is urging people who are in the tropical storm warning areas to start preparing and not pay attention to the track of the system’s center because it could shift. Islands under a tropical storm warning could start feeling tropical storm conditions within 36 hours.

The system is then forecast to move away from Puerto Rico and make a northward turn into the Atlantic’s open waters, where it’s expected to strengthen into a hurricane. The forecast shows it reaching Category 2 level strength by the time it nears Bermuda early Saturday.

NOAA hurricane hunters are expected to investigate the system again Monday afternoon.

What type of weather will the storm bring?

The hurricane center expects tropical storm conditions, including gusty winds and heavy rain, will be felt across portions of the group of islands in the eastern Caribbean Sea late Monday.

“Heavy rainfall may result in locally considerable flash flooding and mudslides in areas of the Leeward Islands and Virgin Islands by later today into Wednesday, and over Puerto Rico late Tuesday into Thursday,” according to the hurricane center’s forecast.

The system, which is being referred to as Potential Tropical Cyclone Five, is forecast to bring 4 to 6 inches of rain over portions of the Leeward and Virgin islands. For Puerto Rico, 3 to 6 inches of rain will be possible, with some areas seeing up to 10 inches of rain, according to the hurricane center. Eastern Hispaniola, the island shared by Haiti and the Dominican Republic, could see 2 to 4 inches of rain.

Storm surge, which is one of the most dangerous part of a system, is forecast to “raise water levels by as much as 1 to 3 feet above ground level for the eastern coast of Puerto Rico from San Juan to Guayama, including the islands of Culebra and Vieques and in the U.S. Virgin Islands, including St. Thomas, St. John, and St. Croix,” according to the hurricane center. “A storm surge will raise water levels by as much as 1 to 3 feet above normal tide levels in the British Virgin Islands. Near the coast, the surge will be accompanied by large and destructive waves.”

Watches and warnings

Tropical storm warning: Puerto Rico, including Vieques and Culebra, U.S. and British Virgin islands, St. Kitts, Nevis, Montserrat, Antigua, Barbuda, Anguilla, Guadeloupe, St. Martin and St. Barthelemy, Sint Maarten.