Upcoming tropical storm has Florida, southeast US on alert

What is likely to become Tropical Storm Debby will strengthen over the eastern Gulf of Mexico this weekend with significant impacts coming to Florida in the short term, followed by dangers along the Carolina coast next week.

A tropical rainstorm is forecast to strengthen while moving northward along the Florida Peninsula's Gulf coast this weekend, spreading rain, gusty winds and severe thunderstorms slowly northward. AccuWeather meteorologists warn that not only may the feature become a hurricane but it may also later stall along the southeastern United States coast next week.

AccuWeather dubbed the wave of low pressure a tropical rainstorm on Monday to raise public awareness as it approached the Leeward Islands with drenching showers and thunderstorms. During the rest of the week, the tropical rainstorm pushed slowly but steadily westward across Puerto Rico, Hispaniola and Cuba.

The feature's next encounter will be with Florida--likely as a strengthening tropical storm this weekend.

A state of emergency was declared in Florida on Thursday evening, a move that will open up additional resources to the state to prepare for the approaching storm. On Friday, the National Hurricane Center classified it as Potential Tropical Cyclone Four.

"As the tropical rainstorm pulls away from Cuba and then moves over the eastern Gulf of Mexico on Saturday, we expect it to gain strength and become a tropical depression and tropical storm," AccuWeather Lead Hurricane Expert Alex DaSilva said.

Water temperatures over the eastern Gulf of Mexico are in the mid- to upper 80s F, which is well above the minimum threshold of 78 F for tropical development. Wind shear, or disruptive steady or shifting breezes, is light in the area where the tropical rainstorm is headed. Moisture is also plentiful around the eastern Gulf. Factoring in these conditions, strengthening is likely.

If it becomes a tropical storm, it will be called Debby.

How much strengthening occurs will depend on how much time the rainstorm spends over the warm water.

"It is possible if the feature bumps along the Florida Peninsula's west coast and interacts with the land, strengthening may be limited," Da Silva said. "A quick landfall over the southwest part of the Florida Peninsula would tend to really limit the time spent over the Gulf and limit the strengthening process. However, if the feature stays more offshore until Sunday evening or night and moves in along the upper Gulf coast of Florida, it may have time to quickly ramp up and become a strong tropical storm or hurricane before pushing inland over northern Florida."

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The AccuWeather RealImpact™ Scale for Hurricanes with the feature is a 1 for the U.S. This scale is not based on wind intensity alone, such as the Saffir-Simpson Hurricane Wind Scale, but rather takes into consideration all weather factors ranging from wind to rain, storm surge and severe thunderstorms, as well as impacts to population and economy.

As the tropical rainstorm turns northward on Saturday and continues on Sunday, rounds of rain, gusty thunderstorms and surf will spread northward over the Florida Peninsula. There is the likelihood of waterspouts in coastal areas and tornadoes over land.

Swimmers will need to exercise extreme caution and obey local restrictions as rip currents will increase in strength and number throughout much of the Florida coastline this weekend.

Enough rain will fall on Florida this weekend to trigger slow travel with areas of urban and low-lying area flooding. Rainfall rates of a few inches per hour can occur in extreme cases, with the AccuWeather Local StormMax™ rainfall for Florida to be 15 inches.

The intensity and track of the feature will determine the storm surge along the Florida Gulf coast initially with up to 3-6 feet of water rise possible along some of the bays where water becomes trapped. This magnitude of storm surge is most likely near and just south of where the center of the storm moves inland.

Later this weekend to early next week, heavy rain, windy conditions and locally severe thunderstorms will spread into part of the mainland of the southeastern U.S.

Tropical rainstorm to re-emerge in Atlantic, possibly strengthen 2nd time

Regardless of where the feature makes landfall in Florida this weekend, it will likely emerge over the Atlantic somewhere along the northern Florida or Georgia coast early next week.

"Steering breezes, which will guide the system steadily along through the weekend, are forecast to weaken early next week, and that could create a problem along the southern Atlantic coast," AccuWeather Chief On-Air Meteorologist Bernie Rayno said, "Should the feature stall along the Carolina coast early next week, there is the potential for excess rainfall that can lead to major flooding."

The AccuWeather Local StormMax™ rainfall for the Carolina and Georgia coast is 25 inches.

Regardless, winds, rain and surf conditions will increase along the Carolinas to southeastern Virginia with dangerous rip currents, storm surge flooding and beach erosion.

Should steering breezes remain steady, due to a dip in the jet stream in the Northeast, the system may be pushed enough to be drawn northward along the mid-Atlantic and New England coasts or possibly farther offshore over the Atlantic.

"Either way, there is the potential for the system to regain strength over the Atlantic early next week after its land interaction with Florida," DaSilva said. "That could mean it may become a hurricane for the first time or regain hurricane status if it strengthens before reaching Florida in the first place."

From Tuesday to Thursday, tropical moisture may interact with a non-tropical storm in the Northeast. That interaction may result in excessive rainfall and flooding well north and west, away from or removed from the tropical feature itself.

Even if the tropical feature stays to the south, seas and surf will build along the mid-Atlantic and southern New England coasts next week.

Super-charged hurricane season anticipated

AccuWeather has not wavered from its prediction of a super-charged hurricane season for 2024 since this past winter.

Record-setting Category 5 Hurricane Beryl demonstrated the concern AccuWeather's team of experts had about the potential energy available to the extremely warm Atlantic waters.

As dry air diminishes and the effects of La Niña unfold late this summer and fall, great numbers of tropical storms and hurricanes are forecast, along with the likelihood of additional storms that intensify rapidly as Beryl did.

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