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Atlantic likely to churn out tropical systems into 2nd half of September

Alex Sosnowski

Since the peak of Atlantic hurricane season, which occurred on Sept. 10, there has been no shortage of Atlantic tropical threats during the last full week of summer. The most menacing of those systems was Imelda, a storm that brewed quickly in the western Gulf of Mexico on Tuesday before moving inland over Texas and unleashing deadly flooding.

Meteorologists were also monitoring Humberto, which strengthened into a major hurricane in the western Atlantic and delivered fierce winds in Bermuda on Wednesday night. The powerful hurricane stayed well east of the United States, but threatened dangerous surf along the coastline.

Not far behind Humberto, Jerry brewed over the open waters of the Atlantic and rapidly strengthened into a hurricane by Thursday before skirting northeast of the Leeward Islands on Friday.

Three additional areas over the Atlantic Basin are being closely monitored for potential tropical development in the coming days, while the western Gulf may be an area to watch late in September or early October.

This image, taken early Saturday morning, Sept. 21, 2019, shows part of the tropical Atlantic Basin. Jerry was near the center of the image with one tropical disturbance east of the Lesser Antilles and another coming off the coast of Africa. (GOES-East/NOAA)

One tropical disturbance was hovering over the central Caribbean, located to the south of Haiti, early Saturday morning.

"While this central Caribbean feature was producing a broad area of showers and thunderstorms, significant wind shear has and is likely to continue to keep this system in check this weekend," Dan Kottlowski, AccuWeather's top hurricane expert, said.

Farther to the east, an area of showers and thunderstorms, located several hundred miles east of the Windward Islands and a couple of hundred miles northeast of the coast of South America, may drift into a zone with conditions more conducive for development into early next week.

Steering winds are likely to push this feature close to the coast of South America initially. However, a northwestward or northward turn over the eastern Caribbean is possible, where waters are quite warm and able to sustain tropical development.

However, rapid and strong development of this feature is unlikely due to wind shear once again. However, some organization and low-end development are possible.

"There is a small chance this system might attempt to wrap up and become a tropical depression from late Sunday to Tuesday," Kottlowski said.

At the very least, an uptick in downpours and locally gusty winds is likely in the Windward and Leeward islands later this weekend and then perhaps across Puerto Rico and Hispaniola from Monday to Wednesday.

Meanwhile, a potent tropical disturbance with a batch of heavy showers and thunderstorms is forecast to move off the coast of Africa this weekend.

Indications are that this feature may have the greatest chance of becoming the Atlantic's next tropical depression and perhaps the 11th named storm of the 2019 hurricane season into next week.

"Because this feature is so far on the edge of the basin, movement and impact, if any on the Lesser Antilles and the Caribbean in general from one to two weeks away is highly uncertain," Kottlowski said.

There is a chance this feature is steered northward over the middle of the Atlantic perhaps before approaching the Lesser Antilles.

While the overall weather pattern will be conducive to spawning long-track Cabo Verde systems, which form off of the coast of Africa, and turning them away from the Atlantic coast of the United States, there is some risk of additional systems forming over the Gulf of Mexico into early October.

Anytime there is a general area of high pressure that lingers from the western Atlantic to the south-central United States, the clockwise flow around this system can generate a broad area of counterclockwise flow, what meteorologists refer to as a gyre, near Central America.

"This gyre can help spin up an organized tropical system from any tropical disturbance that comes along and passes through the wind field," Kottlowski said.

Weak to moderate tropical systems can form in the western Caribbean or the southern and western Gulf of Mexico. These systems could brew with close proximity to land, similar to how Imelda formed near Texas, and thus could form with little lead time before striking.

As we saw with Imelda, a powerful hurricane is not needed to cause great risk to lives and considerable property damage and disruptions due to flooding.

This time of the year, residents, travelers, shipping and cruise interests should closely monitor the tropics as conditions can change significantly from one day to the next.

Hurricane season peak

The Atlantic hurricane season continues through the end of November.