Thursday, September 10, 2020

Tropical disturbance approaching Carolinas to enhance rainfall

 By Alex Sosnowski, AccuWeather senior meteorologist

Published Sep. 10, 2020 3:05 AM Updated Sep. 10, 2020 12:44 PM





As the Atlantic continues its record pace, an area of disturbed weather embedded in a zone of tropical moisture along the United States coast is running out of time to develop into a tropical depression prior to moving onshore later Thursday.

The clock is ticking on the development window for the system as steering breezes will guide the feature onshore in North Carolina by during Thursday evening. Once the system moves over land and away from the very warm waters of the Gulf Stream, any chance of development will cease.

The feature has been experiencing wind shear, which has inhibited development thus far. Wind shear is the increase in straight-line wind speed at progressively higher levels of the atmosphere or the change in direction of winds over a horizontal area of the atmosphere.

"If this shear drops off, then the system could quickly evolve into an organized tropical feature," according to AccuWeather's top hurricane expert Dan Kottlowski.

This infrared image, captured on Thursday morning, Sept. 10, 2020, shows a swirl of clouds about 100 miles to the southeast of North Carolina. (CIRA at Colorado State/GOES-East)

The wind shear was prevented a closed circulation and grouping of thunderstorms near the center of lowest pressure in the region during Wednesday and Wednesday night.

"Regardless of development, this system will add to areas of moderate to heavy rainfall over mostly eastern North Carolina through Thursday and into parts of Virginia during Thursday and Friday," Kottlowski said.

Enhanced downpours from the feature, fully developed or not, will join up with a zone of moisture already present from Florida to the mid-Atlantic region.

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The downpours can be persistent and heavy enough to lead to isolated incidents of flash urban and small stream flooding. Motorists should expect delays and may need to take alternate routes if flooded roadways are in their path.

A wedge of dry air is forecast to drop in across the Northeast this weekend, while areas farther south remain somewhat unsettled.

Showers and thunderstorms associated with this moisture and the enhanced downpours from the tropical disturbance in question will spread inland Thursday and then northeastward at an accelerated rate during Thursday night and Friday.

As this zone of tropical moisture lingers over the adjacent waters over the Atlantic, it is possible for another disturbance to develop some spin during the weekend prior to moving onshore in Florida or perhaps after the disturbance crosses Florida and reaches the eastern Gulf of Mexico early next week.

Meanwhile, thousands of miles to the southeast, Paulette and Rene could be joined by another named system in the coming days as disturbances continue to move westward off the coast of Africa.

RELATED:

The next two names on the list of tropical storms for the 2020 season are Sally and Teddy. One or perhaps both could be utilized by this weekend. With the Atlantic poised to remain hyperactive, early-formation records for both the "S and T" letters are likely going to fall as these were set on Oct. 2 and 5 in 2005, more than three weeks from now.

Thus far this season, there have been 18 tropical depressions, 17 named storms, of which five became hurricanes and one became a major hurricane. The 2020 Atlantic hurricane season has already set 14 early formation records with Cristobal and storms Edouard through Rene.

Earlier this summer, AccuWeather was one of the first to suggest that the Atlantic may be in for a hyperactive year in terms of named tropical systems and the likely need to use the Greek alphabet in naming systems.

There is the potential that 2020 rivals the record number of named storms set during the 2005 season, which yielded 28 named storms.

Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.

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