Sept. 21 -- Forecasters say they are keeping tabs on a potential new tropical threat that's trailing behind Hurricane Fiona, which has turned into a major storm that's now heading toward Bermuda.
Forecasters say the new development in the Atlantic basin could potentially make landfall in United States.
After the Atlantic basin was virtually dormant throughout August, the month of September has been crackling with tropical activity and there are three candidates that could develop into named systems over the next couple of weeks.
The next three names on the 2022 Atlantic list of tropical storms are Hermine, Ian and Julia. Tropical Storm Gaston formed on Tuesday, but it's not expected to be a threat.
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Meanwhile, a strong tropical wave over the western Atlantic has shown signs of organizing -- and there's another robust tropical wave located over western Africa. As this system reaches the Atlantic, it could form and quickly grow into an organized tropical system.
The system that's of greatest concern for people in the Caribbean and possibly the U.S. is a strong tropical wave, which forecasters are considering a tropical rainstorm. The system is designated as Invest 98L by the National Hurricane Center and is located near the northeastern coast of South America.
"This is the most significant threat for the U.S. mainland we've had this hurricane season," AccuWeather Chief Meteorologist Jonathan Porter said.
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"If the main brunt of the tropical rainstorm is able to avoid drifting over South America, it can evolve into a full-fledged tropical storm anytime through Friday while over the eastern Caribbean," AccuWeather Lead Long-Range Meteorologist Paul Pastelok said.
The system could begin to rapidly intensify as it reaches the central and western Caribbean from this weekend to early next week, Pastelok explained.
As the system moves along, it will encounter ideal conditions for a tropical system -- including bath-warm water, according to AccuWeather Hurricane Expert Dan Kottlowski.
Water temperatures are generally in the 80s throughout the Caribbean, Gulf of Mexico and the Florida Straits. Sea surface temperatures are close to 90 degrees Fahrenheit in some places along the system's projected path. That's warm enough to sustain a developing tropical cyclone -- and it's warm enough for explosive strengthening should other environmental factors align.
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Wind shear, or winds that can sometimes disrupt tropical storm formation or organization, is also expected to remain low along the system's track.
At this early stage, and should the system develop, there is a broad zone over which the system may track. That track may depend not only on steering breezes but also on the intensity of the system. A quick-developing, strong system is more likely to turn to the north sooner rather than a weaker system or one that takes longer to develop into a cyclone.
It may also encounter land as it nears southeastern Mexico or Cuba, depending on which direction it takes -- a factor that could limit the strength or organization of the system.
The same type of mechanism, a southward dip in the jet stream, that will keep Fiona away from the U.S., may not be prominent enough to prevent the same scenario for the southern U.S. this time around.
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As the Caribbean system takes shape, another dip in the jet stream could develop over the U.S., potentially creating southerly steering breezes that could guide the storm into the U.S. along the eastern Gulf coast or the Florida Straits. Depending on exactly how the jet stream dip moves along, it could leave a pathway open for areas farther to the west along the Gulf coast to be impacted.
AccuWeather meteorologists say that there is a wide range of possibilities for future movement on the system, which has yet to bud in the Atlantic due to a variety of possible steering and development factors.
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"At this early stage, U.S. interests from Miami to New Orleans should closely watch the evolution of this system," Pastelok said.
Forecasters expect the system to reach major hurricane intensity and say anyone living between the central and western Caribbean to the U.S. Southeast should pay attention. If the storm reaches the Florida Peninsula, there may be an avenue to move northward along the Atlantic Seaboard.
It does not appear that this system would be a threat to areas in the northeastern Caribbean, including Puerto Rico and the Dominican Republic, which were hit hard by Fiona.
Forecasters say the system could move toward Cuba, which could hinder development and keep the system weaker for a time, or on the other hand, the system could move over Central America, which would also prevent the system from becoming strong quickly.
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Another scenario is that it could bypass land and head straight for the Gulf of Mexico -- a possible outcome that would allow the system to pick up strength quicker.
The 2022 Atlantic hurricane season has been largely inactive so far. There have been seven named tropical systems and the closest approach from a hurricane to the U.S. was several hundred miles away.
Hurricane Earl moved east of Bermuda to within about 800 miles of the East Coast at its closest approach -- and on Tuesday Fiona came within 600 miles of Miami.
