1. Tropical storm conditions are possible across portions of thenorthern Leeward Islands, the Virgin Islands, and Puerto Rico Friday night and Saturday, and Tropical Storm Watches have been issued for some of these islands. Heavy rainfall is likely across this area beginning late Friday and could cause mudslides and flash and urban flooding through Sunday.

2. 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 ofHispaniola, Cuba, the Bahamas, and Florida this weekend and earlynext week. Interests there should monitor this system's progressand 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...
- Puerto Rico, Vieques and Culebra
- U.S. Virgin Islands
- British Virgin Islands
- Saba and St. Eustatius
- St. Maarten
- St. Martin and St. Barthelemy
- 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 late Friday and Saturday.

At 800 PM AST (0000 UTC), the center of poorly organized Tropical Depression Thirteen was located near latitude 17.0 North, longitude 55.5 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, near or north of the Virgin Islands and Puerto Rico on Saturday, and near or north of Hispaniola Saturday night.

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

The estimated minimum central pressure based on NOAA Hurricane Hunter data is 1009 mb (29.80 inches).

Recent late afternoon visible satellite imagery has shown evidence of a low-level swirl that is racing away from the persistent area of deep convection. It is unclear if that is the only center of circulation or a swirl rotating around the broader circulation. The initial position for this advisory is a compromise between the earlier estimated center location and the swirl seen in satellite imagery. The initial intensity has been held at 30 kt, based on the earlier ASCAT data.

The initial motion estimate is a somewhat uncertain 290/18 kt. The cyclone is located south of a subtropical ridge that is forecast to build westward over the western Atlantic through early next week. This ridge should steer the system west-northwestward over the next several days, and the suite of dynamical track models continue to be agreement on this overall scenario. The lastest NHC track foreast is similar to the previous advisory and again lies between the HFIP corrected consensus and the TVCA multi-model consensus. It should be noted that since the system is still lacking in organization, there could be some center reformations that result in some shifts in the track forecast.

Although the depression has changed little in strength since itformed yesterday, the overall environment ahead of the systemfavors gradual strengthening. The cyclone is forecast to remainover warm water and in an area of light to moderate vertical windshear. Most of the guidance suggests a little more favorableupper-level wind pattern once the system is north of the GreaterAntilles, but a track farther south would result in more landinteraction, which increases the intensity forecast uncertainty.The updated NHC intensity forecast shows a slightly slower rate of strengthening over the next couple of days, but is unchanged at the latter periods. The overall confidence in both the track and intensity forecasts remain lower than normal.