2 named storms possible in fledgling hurricane season
Atlantic waters could soon come alive with tropical activity in a few key areas of the basin. He breaks down where to watch and what factors may come into play.
AccuWeather meteorologists are closely monitoring the Atlantic basin for the potential that two named storms could develop in the coming weeks. The Atlantic hurricane season is barely more than a week old at this point, but conditions are coming together in a way that could enable the formation of two storms, each in very different areas of the basin.
Forecasters have pegged an area over the Gulf of Mexico as well as another area near Central America over the western Caribbean Sea along with a stretch over the waters off the East Coast of the United States, near the Carolinas, as the potential trouble spots. There's even at least a 50% chance that a disturbance could form and strengthen over the eastern Pacific Ocean and influence how things unfold in the weeks ahead.
Any disturbance that may develop off the East Coast is likely to head out to sea regardless of whether it strengthens into a tropical system or not. However, if a tropical system forms near Belize or southern Mexico, there's a chance it could wander northward toward the U.S. Gulf Coast, a part of the country that has been left vulnerable to flooding due to excessive rainfall in recent weeks.
A weather factor known as a gyre, or a broad area of circulation that causes the atmospheric pressure to drop lower than its surrounding environment, is expected to form and create the conditions under which thunderstorms could erupt. Anytime complexes of thunderstorms form and linger over warm waters, there is the potential for a tropical system to organize gradually.
The graphic above shows where forecasters expect the gyre to take shape over a wide swath of the western Caribbean Sea, Central America and extending into the Pacific basin.
Another factor that will add to the potential for tropical development will be a decrease in wind shear. AccuWeather Senior Meteorologist Dan Pydynowksi said a trifecta of conditions could be the catalyst for development. "Lowering wind shear, warm water and a moistening atmosphere may be enough," for something strong enough to be named to form, he said.
Wind shear is the change in direction and speed of winds at different levels of the atmosphere, and not only can it inhibit the development of tropical systems, it can also influence the track a system takes. While tropical systems can form when high wind shear is present, most form when wind shear is low.
This image, captured on Thursday afternoon, June 10, 2021, shows thunderstorms erupting over the western Caribbean, the southwestern Gulf of Mexico and over the eastern Pacific. Saharan dust was visible in the image, which can inhibit development over the southwestern part of the Caribbean and the southeastern part of the Pacific. (CIRA at Colorado State/GOES-East)
The next two names on the list of tropical storms for the 2021 season are Bill and Claudette. Ana, the first name on the list for this year, developed on May 22 and dissipated over the central Atlantic on May 24.
Should a tropical system take shape near Central America or southern Mexico on the Atlantic side, there are multiple possibilities after formation that forecasters are considering.
One scenario that could play out is that the system could simply move inland over Central America or southern Mexico and then diminish.
In a second scenario, the system may move northwestward over land then regain strength while emerging over the southwestern Gulf of Mexico. A third, and increasingly greater possibility, is the system forms over the southwestern Gulf of Mexico rather than over the Caribbean Sea. On Thursday afternoon, AccuWeather meteorologists had raised this chance of development to about 50%.
One other possibility that AccuWeather meteorologists have pointed out out is that tropical development could occur near the coast over the Eastern Pacific, and that system could then move inland and spin off a system on the Atlantic side, just as Amanda did with Cristobal last year around this time. The phenomenon is sometimes referred to as a crossover storm, given that it crosses over from one basin to another. The chances of this scenario occurring seem to be diminishing as of Thursday.
"Regardless of tropical development or not on either or both the Atlantic or Pacific side, flooding downpours and locally strong winds will impact portions of Central America into southern Mexico this weekend into the upcoming week," Pydynowski said.
Steering winds are expected to be rather light in the region, and a forecast for any definitive track would have to wait until a tropical system has actually formed.
Waters over the western and central Gulf of Mexico and the northwestern Caribbean Sea are approaching 85 degrees, which is sufficiently warm to support a tropical system and allow for anything that might develop to gain in strength.
AccuWeather forecasters advise anyone along the Gulf Coast to monitor the situation in the days ahead. Areas of coastal Texas and Louisiana may be especially vulnerable to flooding should an onslaught of heavy rain produced by a tropical system during the third week of June materialize.
Portions of Texas and Louisiana have received between 1 and 2 feet of rain since the middle of May. The ground is unusually wet for early June, and many rivers and bayous are running high in response to as much as four months' worth of rainfall in less than 30 days.
As for the area off the East Coast of the U.S., a front forecast to push southward from New England at the end of the week is expected to stall over an area covering parts of the Southeastern states and offshore waters in the west-central Atlantic. It is along this frontal zone over the Atlantic where development could take place.
"It is possible a tropical or even sub-tropical (hybrid) system develops just off the Carolina coast this weekend to early next week, especially if the system were to try to form over the warm waters of the Gulf Stream," Pydynowski said.
There is a chance that not only one system tries to form, but perhaps a second system that behaves in a similar manner.
Regardless of tropical, subtropical or non-tropical formation, steering breezes are likely to direct the feature to the northeast and out to sea.
In terms of impacts to the U.S., rough surf and choppy seas are likely along the mid-Atlantic and southern Atlantic coasts to some extent, but those rough waters will also be caused, in part, by an easterly breeze due to high pressure off the New England coast. In fact, that easterly breeze could be more of a factor in rough surf than any tropical or sub-tropical system that may develop.
AccuWeather's team of expert meteorologists anticipates a very active year in terms of the number of named systems. AccuWeather forecasters have also warned of the potential for several direct impacts on the U.S. The team is calling for anywhere from 16 to 20 named storms with seven to 10 hurricanes and three to five direct impacts on the U.S.
The 2020 Atlantic hurricane season set a record with 30 named systems, 14 of which strengthened into hurricanes. There were a record 12 landfalls in the U.S. last year. For comparison, an average hurricane season yields around 14 named storms, with about seven that go on to strengthen into hurricanes, based on data over the 30-year period from 1991 to 2020.
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