Tropical Depression Seven forms; does not pose immediate threat to U.S.
Tropical Depression Seven formed late Wednesday morning and is forecast to bring heavy rain and wind to the Leeward Islands and Puerto Rico through late week.
The National Hurricane Center in Miami has been closely monitoring a tropical wave called Invest 96L in the Atlantic for potential development for several days. Convection associated with Invest 96L was persistent overnight Tuesday, despite being confined to the eastern portion of the circulation. By late Wednesday morning, Invest 96L possessed a better defined circulation and was classified as Tropical Depression Seven. Moderate westerly wind shear, which is the change of wind speed or direction with height, coupled with dry mid-levels are expected to keep Tropical Depression Seven from significant intensification through Friday.
Tropical Depression Seven could become Tropical Storm Fiona as early as Wednesday evening according to the latest advisory from the National Hurricane Center. If this occurs, it would be the sixth named tropical cyclone of the Atlantic hurricane season, arriving nearly two weeks later than average.
Official forecasts for soon-to-be Tropical Storm Fiona indicate a continued westerly track, likely reaching the Leeward Islands by late Friday with heavy rainfall and gusty winds. Fiona is expected to reach the Virgin Islands and Puerto Rico by Saturday before reaching the Dominican Republic Sunday afternoon. Heavy rains in the mountainous terrain of Puerto Rico and the Dominican Republic could result in mudslides over the weekend, with localized flash and urban flooding possible outside of higher elevations.
Tropical storm watches are expected for the Leeward Islands by Wednesday night according to the 5 p.m. advisory issued by the National Hurricane Center. Watches are likely to expand to include Puerto Rico and the Virgin Islands by Thursday. The island of Hispaniola, containing both the Dominican Republic and Haiti, are forecast to be impacted by Fiona later this weekend with potential watches not likely until Friday.
Here are the 5 PM AST Wednesday Key Messages for Tropical Depression #Seven. A Tropical Storm Watch will likely be required for portions of the Leeward Islands this evening or overnight. Follow the latest at https://t.co/tW4KeGe9uJ pic.twitter.com/0dtRZvWVHo— National Hurricane Center (@NHC_Atlantic) September 14, 2022
Where Fiona tracks after exiting Hispaniola is uncertain. A large ridge of high pressure is forecast to linger over the Atlantic. The exact strength and location of this ridge, called a Bermuda high, can impact where tropical cyclones go. Long-range forecast models Wednesday evening keep Fiona away from Florida, but do provide an increase in tropical moisture across the state by early next week. This will likely result in continued daily downpours and the risk of localized flash flooding. Residents are encouraged to monitor the forecast in the days to come, as changes to the forecast could have implications for South Carolina's weather by the second half of next week.