Tammy Forms, To Impact the Northern Lesser Antilles by Friday

Hurricane hunters find Tammy stronger this morning, with winds topping 60 mph

Thursday morning satellite of Tropical Storm Tammy east of the Lesser Antilles. Credit: NOAA

Invest 94L – the disturbance that first rolled off Africa 8 days ago – was upgraded to Tropical Storm Tammy on Wednesday afternoon, becoming the 20^th named storm of the 2023 Atlantic hurricane season. Only three other hurricane seasons – 2021, 2020, and 2005 – have had at least 20 named storms by this point in the hurricane season.

Tropical Storm Watches are currently in place for parts of the Lesser Antilles – from Barbados and Martinique in the south to Antigua and Barbuda in the north – for the possibility of tropical storm conditions by as early as tomorrow. The watches will likely be upgraded to warnings later today and hurricane watches could be required for some of the islands in Tammy’s path.

Hurricane hunters investigating Tammy early Thursday found the storm stronger than initially thought, prompting the National Hurricane Center to issue a special mid-morning advisory. The updated forecast calls for Tammy to become a hurricane as it begins to pull away from the islands on Saturday.

Forecast models continue to come into better agreement with Tammy brushing the northeastern islands of the Caribbean as a strong tropical storm or hurricane starting on Friday and continuing through Saturday. Models have slowed some with Tammy’s forward speed since yesterday, but the system should be accelerating northward and away from the northern Leeward Islands by late Saturday.

Global model forecasts for Tammy, with shaded colors indicating the odds of Tammy’s center passing within 100 miles of a given location. Both the European and American models (red and green lines in the graphic) are in good agreement with Tammy passing near or over the northeastern islands of the Caribbean on Friday into Saturday. Credit: Tomer Burg/University of Oklahoma

Although Tammy may briefly strengthen as it accelerates northeastward ahead of an approaching mid-Atlantic cold front early next week, it will pass well east of Bermuda and remain over the open Atlantic.

The primary impacts from Tammy – including its heaviest rains and strongest winds – should stay east of Puerto Rico and the Virgin Islands. Moderate wind shear from the southwest may shunt much of Tammy’s weather to its eastern side, so assuming the storm stays east as forecast, these areas will remain on its drier and less windy side. Puerto Rico and the Virgin Islands, however, should continue to monitor the forecasts in the days ahead.

Tammy poses no threat to Florida or the mainland U.S.

Behind Tammy, the Atlantic will stay quiet into next week.