More Tropical Systems May Brew in Atlantic During September Despite El Nino

By Alex Sosnowski, AccuWeather.com Senior Meteorologist

September 1,2015; 9:28PM,EDT

 

 

A rapid shutdown of tropical activity and an end to hurricane season in early September are not likely this year, despite a strong El Niño.
While there are no powerful tropical systems in the Atlantic at present, there will continue to be several areas to watch through the Labor Day weekend and beyond.

The system with the greatest potential to develop in the short term is currently a weak non-tropical storm moving slowly away from the Carolina coast. The storm was responsible for flooding rainfall in Charleston, South Carolina, to start the week.
According to AccuWeather Hurricane Expert Dan Kottlowski, as the system moves toward Bermuda, atmospheric conditions could become more favorable for development this weekend.

"All indications are that if a tropical or subtropical storm were to evolve near Bermuda it would not impact the United States and might even steer clear of Atlantic Canada," Kottlowski said.
As the system, tropical or not moves eastward initially, showers and thunderstorms would affect Bermuda Thursday into Friday night. Either clearing or squalls with increasing wind would follow over the weekend, depending on whether or not the system develops and stalls.
Any impact on Atlantic Canada would not occur until next week.
Another area that bears watching is a disturbance over the western Gulf of Mexico, along the Texas coast.
Steering flow will tend to push this system northward and into the lower Mississippi Valley during the middle days of the week.

However, if the system managed to stay over warm Gulf of Mexico waters longer, it could develop into a tropical depression or storm.
"The area is in a good spot for development, but we do not see much evidence of a circulation center at this time," Kottlowski said.
Regardless as to whether or not the system develops, it will spread locally drenching downpours and locally gusty thunderstorms northward along the Texas coast through Wednesday and then into Louisiana, Arkansas and Mississippi Wednesday into Thursday.
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Bathers and boaters in the region should be on the lookout for rapidly changing weather conditions due to gusty squalls. Enough rain can fall from the system to cause flash flooding.
Meanwhile, the circulation from once Tropical Storm Erika is barely noticeable in the eastern Gulf of Mexico, near Florida. However, the system will continue to focus showers and thunderstorms near its center.

Even after the Gulf systems and the near-shore Atlantic systems depart or dissipate, areas along the Gulf Coast to the southern Atlantic coast of the U.S. will remain unsettled through the Labor Day weekend with occasional showers and thunderstorms.
Thousands of miles to the east in the Atlantic, Fred recently brought hurricane conditions to the Cape Verde Islands.
Based on records since about 1950, Fred was the farthest east a hurricane ever formed in the Atlantic.
Fred will continue to weaken as it moves northwestward over the central Atlantic with no threat to land following the Cape Verde Islands.
Farther east still, tropical disturbances will continue to roll off the Africa coast well into September.
"This is the prime time of the year for Cape Verde systems [westward-moving disturbances in the Equatorial Atlantic]," Kottlowski said. "Large areas of wind shear and dry air are still present, but they are not as ferocious as they were earlier in the season over much of the region."
During strong wind shear, there is a rapid change in the direction and speed of the flow of air at different levels of the atmosphere which tend to prevent tropical storm formation or limit early development.
Despite the influence of El Niño on the Atlantic basin this year, AccuWeather meteorologists do not expect a complete shutdown of tropical activity and an early end to hurricane season during September.
"The main areas to watch for development moving forward through the height of hurricane season and into late September will be from the Africa coast to the Caribbean and the southern Gulf of Mexico," Kottlowski said.
Current loop of the tropical Atlantic basin. (Satellite/NOAA)
While El Niño does not reduce the number of tropical disturbances moving westward from Africa, it does limit the number of tropical storms and hurricanes in the Atlantic basin in general.
The reduction is due to more pronounced areas of wind shear and dry air during El Niño.
However, El Niño does not tend to reduce the number of strong systems so much, such as Category 3 hurricanes or greater. If a system can move into a pocket of favorable conditions with low wind shear and moisture, then it can still progress to a major hurricane.
As of Sept. 1, 2015, there have been four tropical storms, two hurricanes and one major hurricane for the Atlantic season.
While the forecast for the number of systems and landfalls are meant to be used as a rough guide, based on the AccuWeather 2015 Atlantic Hurricane Forecast, there is still room for more hurricanes, tropical storms and another landfall in the U.S. before the official season draws to a close in November.