1. Isaias will produce heavy rains and potentially life-threatening flash flooding and mudslides across the Virgin Islands, Puerto Rico, the Dominican Republic, northern Haiti, and over the southeastern Bahamas.

2. Tropical storm conditions are likely across portions of the the Virgin Islands, and Puerto Rico through tonight and will spread westward to portions of the Dominican Republic, Haiti, and the southeastern Bahamas and Turks and Caicos and the Central Bahamas on Thursday and Friday. Tropical Storm Warnings are in effect for these areas. Do not focus on the details of the track forecast, as rainfall and wind hazards will extend far from the center of the system. 3. While this system could bring some rainfall and wind impacts to portions of Cuba, the northwestern Bahamas, and Florida later this week and this weekend, it is too soon to determine the location or magnitude of those impacts. Interests there should monitor the progress of this system 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 Warning is in effect for...
- Puerto Rico, Vieques, Culebra
- U.S. Virgin Islands
- British Virgin Islands
- St. Martin and St. Barthelemy
- Saba and St. Eustatius
- St. Maarten
- Dominican Republic entire southern and northern coastlines
- North coast of Haiti from Le Mole St Nicholas eastward to the northern border with the Dominican Republic
- Turks and Caicos Islands
- Southeastern Bahamas including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, and the Ragged Islands
- Central Bahamas, including Cat Island, the Exumas, Long Island, Rum Cay, and San Salvador

A Tropical Storm Watch is in effect for...
- Northwestern Bahamas including Andros Island, New Providence, Eleuthera, Abacos Islands, Berry Islands, Grand Bahamas Island, and Bimini

Interests in Cuba and the Florida peninsula should monitor the progress of this system.

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

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

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 Isaias can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC, and on the web at www.hurricanes.gov/text/MIATCDAT4.shtml.

WIND: Tropical storm conditions will continue across portions of the Leeward Islands, the U.S. and British Virgin Islands and Puerto Rico overnight. These conditions are forecast to reach portions of the Dominican Republic and Haiti within the warning area by this morning, and the southeastern Bahamas and Turks and Caicos this afternoon. Tropical storm conditions are expected in the Central Bahamas beginning Friday morning and are possible in the northwestern Bahamas beginning late Friday.

RAINFALL: Isaias is expected to produce the following rain accumulations:

Across the Bahamas: 4 to 8 inches.

Across the British and U.S. Virgin Islands and Turks and Caicos: 3 to 6 inches.

Across Puerto Rico, the Dominican Republic, northern Haiti, and eastern Cuba: 3 to 6 inches, with isolated maximum totals of 8 inches.

These rainfall amounts may lead to lifethreatening flash flooding and mudslides, as well as potential riverine flooding beginning today. Urban and small stream flooding is expected for the U.S. Virgin Islands, eastern Puerto Rico, and Hispaniola.

SURF: Swells generated by Isaias will be affecting portions of the Leeward Islands, the Virgin Islands, and Puerto Rico through today. These swells are forecast to reach the north coast of the Dominican Republic, the Turks and Caicos Islands and the southeastern Bahamas this morning. These swells are likely to cause lifethreatening surf and rip current conditions. Please consult products from your local weather office.

At 200 AM AST (0600 UTC), the center of Tropical Storm Isaias was located near latitude 16.7 North, longitude 67.2 West. Isaias is moving toward the northwest near 18 mph (30 km/h), and a westnorthwestward to northwestward motion with some decrease in forward speed is expected over the next couple of days. On the forecast track, the center of Isaias will move over Hispaniola late today and near the Southeastern Bahamas by early Friday.

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. Some weakening is likely when the center moves over Hispaniola with some restrengthening expected by Friday.

Tropicalstormforce winds extend outward up to 345 miles (555 km) mainly to the northeast of the center. A Weatherflow station on Culebra recently reported sustained winds of 45 mph (72 km/h) with gusts to 53 mph (85 km/h).

The estimated minimum central pressure is 1004 mb (29.65 inches).

vations from recent scatterometer passes over the system show that it now has a sufficiently well-defined center to be designated as a tropical cyclone. The current intensity is estimated to be 45 kt, but these winds are currently occurring over the Atlantic waters well to the north and northeast of the center. Since the cyclone is expected to move over Hispaniola on Thursday some weakening is likely within the next 24 hours. However since Isaias has such a broad wind field, the weakening will probably not be as significant as in a typical tropical cyclone with a small radius of maximum winds. Also, a re-formation of the center to the north of Hispaniola may occur. Later in the forecast period some strengthening is likely, although this may be offset by southwesterly wind shear on the order of 20 kt in 2-3 days. The official forecast is close to the intensity model consensus but well below the latest LGEM guidance. The scatterometer data show that the center of the system is south of the previously estimated track, so there is a lot of uncertainty in the initial motion estimate of 285/17 kt. Isaias should move on a west-northwestward to northwestward track on the southern and southwestern side of a mid-tropospheric ridge. In 2-3 days, the system is expected to turn north-northwestward due to a weakness in the ridge and an approaching trough. Later in the forecast period, the trough should cause Isaias to turn toward the northeast. The official track forecast is a little to the east of the previous one and a little west of the simple and corrected dynamical model consensus tracks. It should be noted that further adjustments to the forecast tracks are indeed possible, especially after Isaias moves north of Hispanio