1. Tropical storm conditions are possible across portions of thenorthern Leeward Islands by Friday night, and Tropical Storm Watcheshave been issued for some of these islands. Heavy rainfall islikely across this area beginning late Friday.

2. There is a risk of tropical storm conditions in the VirginIslands and Puerto Rico Friday night and Saturday and TropicalStorm Watches could be required for these islands later today.Interests there should closely monitor the progress of this system.

3. The details of the long-range track and intensity forecasts aremore uncertain than usual since the system could move over portionsof the Greater Antilles this weekend. However, this system couldbring some storm surge, rainfall and wind impacts to portions of Hispaniola, Cuba, the Bahamas, and Florida this weekend and early next week. Interests there should monitor this system's progress and updates to the forecast over the next few days.

CHANGES WITH THIS ADVISORY:

None

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
- Saba and St. Eustatius
- St. Maarten
- Antigua, Barbuda, St. Kitts, Nevis, and Anguilla

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.

Interests elsewhere in the northern Leeward Islands, the Virgin Islands, and Puerto Rico should monitor the progress of this system, as additional tropical storm watches or warnings will be required for portions of those areas later today.

For storm information specific to your area, please monitor products issued by your national meteorological service.

RAINFALL: The depression is expected to produce 1 to 3 inches of rain with isolated maximum totals of 5 inches over the northern Leeward Islands, and maximum totals of 3 to 6 inches over Puerto Rico and the Virgin Islands through Sunday.

WIND: Tropical storm conditions are possible within the watch area by late Friday.

At 200 PM AST (1800 UTC), the center of Tropical Depression Thirteen was located near latitude 16.0 North, longitude 52.8 West. The depression is moving toward the westnorthwest near 21 mph (33 km/h) and this motion is expected to continue for the next few days. On the forecast track, the depression is expected to move near or north of the northern Leeward Islands by late Friday and near or north of the Virgin Islands and Puerto Rico on Saturday.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Gradual strengthening is forecast, and the depression is expected to become a tropical storm later today or tonight.

The estimated minimum central pressure is 1008 mb (29.77 inches).

The organization of the depression has not changed much overnightor this morning. An area of convection has persisted near theestimated center, with some banding noted over the northwesternportion of the circulation. An earlier SSMIS overpass was veryhelpful in locating the center of what appears to be a small circulation. A very recent ASCAT overpass has also revealed a small circulation that is weak on the southeastern side, but with winds near tropical storm strength to the north of the center. The ASCAT data along with subjective Dvorak classification from TAFB and SAB support maintaining the 30-kt initial intensity. The depression continues to move briskly west-northwestward or290/18 kt. The track forecast philosophy has not changed frombefore. A subtropical ridge over the central Atlantic is forecastto build westward and strengthen over the next several days. This pattern is expected to keep the cyclone on a west-northwestward heading throughout the forecast period. The dynamical models continue to agree on this overall scenario, but there some differences in both forward speed and how close it gets to the Greater Antilles. In general, the models that indicate a stronger cyclone favor a more northern track, while those which depicted a weaker system are along the southern and faster side of the envelope. The latest consensus aids are little north of the previous track, and the new NHC forecast lies between the HFIP corrected consensus and the TVCA multi-model consensus. This is slightly north of the previous advisory, and not far from the GFS ensemble mean.

The environment consisting of light to moderate vertical wind shearis expected to allow for gradual strengthening over the next fewdays, and the NHC forecast calls for the system to become a tropicalstorm later today or tonight. The upper-level wind pattern isexpected to remain favorable in the latter portion of the forecastperiod, and if there is minimal land interaction, a faster rate ofstrengthening is possible at that time. The NHC intensity foreastnow shows the system becoming a hurricane by 96 hours, but it is alittle lower than the consensus aids at days 4 and 5 due touncertainty in how much the system will interact with the Greater Antilles.