1. Tropical storm conditions are expected over portions of the Leewards Islands this morning and the Virgin Islands and Puerto Rico today. Tropical storm conditions are expected over eastern parts of the Dominican Republic tonight and Monday. Tropical storm conditions are possible over western portions of the Dominican Republic and Haiti Monday and Monday night.

2. Heavy rainfall could lead to flash and urban flooding over the Leeward and Virgin Islands, Haiti and the Dominican Republic. 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 the rest of the Dominican Republic, Haiti, the Turks and Caicos Islands, the Bahamas, Cuba, and Florida, but forecast uncertainty remains higher than usual. Interests in those areas should monitor the progress of Grace and updates to the forecast.

CHANGES WITH THIS ADVISORY: The government of the Dominican Republic has issued a Tropical Storm Warning from Cabo Caucedo to the southern Haitian Border. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for...
- Saba and Sint Eustatius
- Sint Maarten
- St. Martin and St. Barthelemy
- U.S. Virgin Islands
- Puerto Rico, including Vieques and Culebra
- Dominican Republic from the southern Haitian border to Samana A Tropical Storm Watch is in effect for...
- North coast of the Dominican Republic from the Haitian border to Samana
- Entire coast of Haiti A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. Interests elsewhere in the Dominican Republic, Haiti, the Turks and Caicos Islands, the southeastern Bahamas, and Cuba should monitor the progress of Grace. Additional watches and warnings could be required for some of these areas 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 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 in the Leeward Islands this morning, in the Virgin Islands and Puerto Rico today, and in the Dominican Republic tonight and Monday. Tropical storm conditions are possible within the watch area in the Dominican Republic Monday, and in Haiti on Monday night.

RAINFALL: Grace is expected to produce the following rainfall amounts Sunday into Tuesday: 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 with isolated maximum totals of 8 inches. Heavy rainfall could lead to flash, urban and small stream flooding and possible mudslides. Over Haiti and the Dominican Republic ...4 to 7 inches with isolated maximum totals of 10 inches. Heavy rainfall could lead to flash and urban flooding and possible mudslides from Monday into Tuesday. By mid to late week, heavy rainfall from this system could impact portions of Cuba, the Bahamas and Florida.

At 500 AM AST (0900 UTC), the center of Tropical Storm Grace was located near latitude 16.9 North, longitude 64.4 West. Grace is moving toward the west northwest near 16 mph (26 km/h). A continued west northwestward motion at a slower forward speed is expected over the next few days. Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Some strengthening is expected before Grace reaches Hispaniola on Monday. Weakening is forecast as the system crosses Hispaniola Monday and Monday night. Little change in strength is expected on Tuesday. Tropical storm force winds extend outward up to 35 miles (55 km) from the center. The estimated minimum central pressure is 1010 mb (29.83 inches).

Radar data from the Leeward Islands and Puerto Rico, as well as satellite images, indicate that Grace is still not a well-organized tropical cyclone, although over the past few hours banding features have become more evident and the outflow has improved. An earlier ASCAT-C overpass showed peak winds of 30 kt associated with Grace, and the latest Dvorak intensity estimate from TAFB was 35 kt. Assuming some undersampling from the ASCAT instrument, the initial intensity estimate remains 35 kt for this advisory.

Grace continues to move fairly quickly to the west-northwest, or 285/18 kt to the south of a strong mid-level ridge. Aside from the HWRF, which is a northern outlier and has not performed particularly well for Fred or Grace, and also the Canadian model, which is a southern outlier, the track guidance has come into better agreement on the future path of Grace. The cyclone is expected to slow its forward speed today, and maintain a west-northwestward motion to the south of the ridge for the next several days. The NHC track forecast is little changed from the previous one through 72 h, and then was adjusted a little to the south of the previous one thereafter. On this path, Grace would pass just south of Puerto Rico later today, cross Hispaniola tonight through Monday night, then move along the northern coast of Cuba Tuesday and Wednesday.

Grace is in an environment favorable for intensification, and the NHC intensity forecast calls for modest strengthening to 45 kt before it reaches the Dominican Republic Monday morning. This portion of the forecast is in good agreement with the various consensus models. The intensity forecast becomes highly uncertain thereafter, and is dependent on how much of the Greater Antilles the cyclone interacts with. Based on the current track forecast, Grace would cross a large portion of the rugged terrain of Hispaniola, then interact with the landmass of Cuba for a couple of days. There is a decent chance that the low-level center of Grace could dissipate over Hispaniola as the system opens back into a tropical wave. However, due to the possibility of the center remaining intact after crossing that landmass, the NHC forecast calls for weakening followed by little change in strength thereafter as it moves along the Cuban coastline. The latest NHC intensity forecast beyond 24 h is little changed from the previous one, and is close to the FSU Superensemble.