1. Tropical storm conditions are expected in portions of the Leeward Islands by tonight or early Sunday, and the U.S. Virgin Islands and Puerto Rico on Sunday. Tropical storm conditions are also possible over the British Virgin Islands on Sunday. The risk of strong winds will then spread westward to the Dominican Republic Sunday night and Monday.

2. Heavy rainfall could lead to flash and urban flooding over the Leeward and Virgin Islands. Across Puerto Rico, heavy rainfall may lead to flash, urban and small stream flooding, along with the potential for mudslides.

3. There is a risk of wind and rainfall impacts across Haiti, the Turks and Caicos Islands, the southeastern Bahamas, Cuba, and Florida next week, and interests in those areas should monitor the progress of this system.

CHANGES WITH THIS ADVISORY:

The government of Antigua and Barbuda has issued a Tropical Storm Warning for the British Virgin Islands.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
- Antigua and Barbuda, Anguilla, St. Kitts and Nevis, and Montserrat
- Saba and Sint Eustatius
- Sint Maarten
- St. Martin and St. Barthelemy
- British Virgin Islands
- U.S. Virgin Islands
- Puerto Rico, including Vieques and Culebra

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.

Interests in the Dominican Republic and Haiti should monitor the progress of this system. Additional watches and warnings will likely be required for this area later today.

For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service.

Key messages for Tropical Storm Grace can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT2 and WMO header WTNT42 KNHC and on the web at www.hurricanes.gov/graphics_at2.shtml?key_messages.

WIND: Tropical storm conditions are expected within the warning area over the Leeward Islands by tonight or early Sunday, and the Virgin Islands and Puerto Rico beginning on Sunday.

RAINFALL: The system is expected to produce the following rainfall amounts later today into Monday:

Over the northern Leeward Islands and Virgin Islands...3 to 6 inches. This rainfall may produce scattered areas of flash and urban flooding.

Over Puerto Rico...3 to 6 inches. Heavy rainfall could lead to flash, urban, and small stream flooding as well as potential mudslides.

Heavy rainfall from this system could impact Florida late next week.

At 800 AM AST (1200 UTC), the center of Tropical Storm Grace was located near latitude 15.9 North, longitude 56.6 West. Grace is moving toward the west near 22 mph (35 km/h). A motion toward the west with a gradual decrease in forward speed is expected during the next few days. On the forecast track, the center of the storm is forecast to move over the Leeward Islands tonight, over the Virgin Islands and Puerto Rico on Sunday, and then over the Dominican Republic on Monday.

Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Some strengthening is forecast during the next couple of days. Weakening is expected early next week as the system interacts with the Greater Antilles.

Grace is a small tropical storm. Tropicalstormforce winds extend outward up to 25 miles (35 km) from the center.

The estimated minimum central pressure is 1007 mb (29.74 inches).

The cyclone has become a little better organized overnight, with an area of concentrated convection persisting over the center for the past several hours. The system remains compact, with the convective canopy about 100 n mi in diameter, while earlier ASCAT data revealed winds greater than 25 kt extended only about 30 n mi from its center, with peak winds of 27 kt. Despite the weaker maximum winds sampled earlier this evening, the increase in organization of such a small system has likely produced a notable increase in the surface winds near the center. In addition the latest Dvorak intensity estimates from TAFB, SAB, and the UW-CIMSS ADT and SATCON suggest that the intensity is now somewhere between 30 and 45 kt. Based on a conservative blend of these values, it is estimated that the Tropical Depression Seven has strengthened into 35-kt Tropical Storm Grace.

Grace continues to move quickly westward, with an initial motion of 280/19 kt. A strong mid-level ridge to the north of the storm should continue to steer it westward for the next few days. Beyond that time, the forecast models begin to diverge in their track solutions, as they vary in the strength of the ridge. Overall, the models have trended toward a stronger, more persistent ridge to the north of the cyclone for the latter half of the forecast period, and as such the model solutions are generally showing a track that lies a bit south of the previous runs for those time periods. The official NHC forecast track is little changed through 72 h and lies near the middle of the tightly clustered track guidance. Beyond 72 h, the forecast track has been shifted slightly to the south, but still lies to north of the consensus model tracks.

The earlier bout of wind shear that had entrained surrounding dry air into Grace appears to have abated, at least in the short term. And, global models indicate that the shear will remain low for about the next 24-36 h while the cyclone moves over increasing SSTs. Therefore, it is reasonable to assume that strengthening should occur over the next day or so. Thereafter, the intensity forecast becomes somewhat complicated as the system is forecast to interact with an upper-level trough while possibly crossing the Greater Antilles at the same time. Slight weakening is indicated in the NHC intensity forecast as the system crosses the northern portion of the Dominican Republic early next week. Thereafter, moderate to strong northerly shear is forecast to impact Grace as the system moves into the flow on the western side of an upper-level trough over the western Atlantic. This shear should prevent any further strengthening through the end of the forecast period. The intensity forecast is a little lower than a blend of the NOAA HCCA and IVCN consensus, as there is likely a high bias from the HWRF in these solutions. The latter portion of the NHC intensity forecast is of lower-than-normal confidence due to the potential for a longer amount of time over the rugged terrain of the Greater Antilles than indicated, and also due to the fragile nature of the small cyclone and the possible effects of the stronger shear later in the forecast period.