Tropical Storm Watch issued for Dominica

Tropical Storm Watch has been issued for Dominica amidst the passage of TS Tammy. The situation of Heavy Rainfall, Flooding, Gusty Winds in Parts of Lesser Antilles Friday to Weekend are possible

Tropical Storm Watch issued for Dominica
Tropical Storm Watch issued for Dominica

Weather: Tropical Storm Watch has been issued for Dominica amidst the passage of TS Tammy. The situation of Heavy Rainfall, Flooding, Gusty Winds in Parts of Lesser Antilles Friday to Weekend are possible.

NHC has raised confidence in 94L becoming a tropical depression or storm 80% during the next day or so. Track path shifted more south into the islands.

In the 1st images of visible satellite so far, the circulation looks more robust… although it’s masked by mid-upper clouds. It is stretched a bit to the NW by a surge in the trade winds which has an area of convergence. This will push quickly into the Lesser Antilles Thursday bringing showers and isolated thunderstorms with a few gusty winds.

Edited: 94L looks like it is moving more west and faster [but average at 2am was WNW near 16mph] its 8am position was near 12.5N 48.5W. Winds 35mph. 1008mb.

Main models have forecast tracks more south and west into the North Windwards to Leewards with a few just east and GFS farthest east. The Euro is weakening as it brings core near Dominica/Guadeloupe.

The average of ensemble model tracks has come closer to the Leewards including GFS, Canadian, UKMET, Euro.

The GFS which was farthest east came a bit closer. The average track of 4 reliable model ensembles has continued to trend closer or over the Leewards (black line is latest forecast from 8pm Tues).

Using 4 reliable model ensemble track average, the % chance of tracks over the Leewards is medium but peak is over those islands(green/yellow).

Some forecast ideas: 94L has high moisture near its core but dry air to its north is pushing into the outer regions. The wind shear from an upper low to the west is backing off but there is some to the northeast from an upper trough which is also causing sinking dry air.

The shear is forecast to reduce later today to Friday. 94L has started to move over very warm 29-30C water and will move over deeper warm water from tonight. Models disagree on how strong it can get but given that the structure is still not well formed and the large size, it may take time and reach weak to moderate storm status by late Friday as it nears the islands.

The stronger forecasts mostly take it further north or east of the islands. There is a SHIPS forecast from last night showing a decent chance of rapid strengthening next 24-48 hours but that is probably less likely.