AccuWeather meteorologists are tracking a feature over the Atlantic Ocean that has a chance of evolving into a tropical storm before approaching the United States later this week or early next. The feature has some hurdles along the way, but conditions may become more favorable for development later on, especially as it approaches the U.S.
During the summer and autumn, a series of low pressure areas, known as tropical waves, moves from the Indian Ocean across Africa then the Atlantic. Of these, a small number go on to evolve into tropical depressions, tropical storms and hurricanes. August marks a time when the number of tropical waves that organize tends to increase substantially.
Tracking a troublesome tropical wave
One particular tropical wave that caught AccuWeather meteorologists’ attention last week is a few hundred miles to the east of the easternmost islands of the Caribbean. The wave has a medium chance of developing. “The tropical wave is currently battling a harsh environment in a sea of dry air as it moves west across the Atlantic,” AccuWeather Lead Hurricane Expert Alex DaSilva said. “The dry air is working to keep the wave from gaining any organization.”
Wind shear, which is the effect of stiff, steady breezes in one direction or shifting directions, can inhibit tropical development or, in some cases, cause an established tropical storm to weaken. “Toward the end of this week, the wave will move into an area with fairly low shear and ample moisture, and that could allow some organization and strengthening,” DaSilva added.
This feature will interact with another ripple in the atmosphere early this week, causing the two to consolidate into one low-pressure area. Exactly how these two interact and where they re-form as a single tropical rainstorm may determine the future path near the Caribbean this week and perhaps the U.S. beyond.
Proximity to large Caribbean islands may be a deterrent
“A major caveat is where the tropical rainstorm tracks,” DaSilva said, “If it tracks north [or south] of the Greater Antilles, then it will have a better chance to develop as it will be removed from the towering mountains of Puerto Rico, Hispaniola and Cuba.” Large, high mountains disrupt the wind flow of a tropical feature and can inhibit its wind intensity.
A tropical rainstorm that bounces westward, along the high mountains of the Greater Antilles, would likely struggle to organize. However, if the center stays away from the islands and their mountains, the waters are sufficiently warm to allow organization and strengthening.
Should the storm track north of the big islands in the northern Caribbean later this week, it would more likely be a concern for the East Coast of the U.S. later on. On the other hand, should the storm track just south of the big islands, it may be more concerning for the U.S Gulf Coast later on.
Contingent impacts on the Caribbean
If the storm passes close to or over the islands, a period of heavy rain, gusty thunderstorms and rough seas will progress westward over part of the northern Caribbean. Because of this concern, AccuWeather meteorologists are referring to the wave as a tropical rainstorm. How intense conditions become will depend on the strength and track of the tropical rainstorm.
Heavy rain that triggers flash flooding and mudslides could be a concern as well as high winds that might lead to damage and power outages. Building seas would create dangerous coastal conditions for boating and beach interests and possibly storm surge coastal flooding.
High pressure over central Atlantic to push tropical rainstorm along
Another player will be a large area of high pressure over the central Atlantic, pushing the storm to the west, but only for so long. Later this weekend to next week, steering winds should turn the storm to the northwest or north near the U.S.
Because of these conditions, everyone from the northern Caribbean to the Bahamas and from the U.S. Gulf Coast to the Carolinas will have to watch this tropical feature closely. By later this weekend to early next week, the storm could be turning northward along the U.S. Atlantic coast or could be churning waters over the Gulf of Mexico, prior to moving onshore.
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