1. Tropical storm conditions will continue in portions of the Lesser Antilles during the next several hours. Tropical storm conditions are expected and hurricane conditions are possible in Puerto Rico on Wednesday and in portions of the Dominican Republic Wednesday night and Thursday.

2. Heavy rainfall over portions of the Lesser Antilles, Puerto Rico, and the Dominican Republic could produce flash flooding during the next few days.

3. The threat of winds and heavy rains later this week into this weekend in the Turks and Caicos, the Bahamas, and Florida is increasing. Residents in these areas should monitor the progress of Dorian and ensure that they have their hurricane plan in place.

4. Uncertainty in the intensity forecast later this week remains higher than usual due Dorian's potential interaction with Hispaniola and Puerto Rico.

WHAT'S NEW:

The government of the Dominican Republic has issued a Tropical Storm Warning from Isla Saona to Samana. The Tropical Storm Warning has been discontinued for St. Vincent and the Grenadines. The Tropical Storm Watch has been discontinued for Grenada and its dependencies.

SUMMARY OF ALERTS:

A Hurricane Watch is in effect for...
- Puerto Rico
- Dominican Republic from Isla Saona to Samana

A Tropical Storm Warning is in effect for...
- Martinique
- Puerto Rico
- Dominican Republic from Isla Saona to Samana

A Tropical Storm Watch is in effect for...
- Dominica
- Saba and St. Eustatius
- Dominican Republic from Isla Saona to Punta Palenque
- Dominican Republic from Samana to Puerto Plata

A Hurricane Watch means that hurricane conditions are possible within the watch area.

A watch is typically issued 48 hours before the anticipated first occurrence of tropicalstormforce winds, conditions that make outside preparations difficult or dangerous.

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. Interests in the Virgin Islands should monitor the progress of Dorian. 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.

RAINFALL: Dorian is expected to produce the following rain accumulations through Thursday:

Martinique to Saint Vincent...3 to 6 inches, isolated 10 inches. Grenadines to Grenada...1 to 3 inches. Guadeloupe to Dominica...1 to 4 inches. Puerto Rico and Dominican Republic...4 to 6 inches, isolated 8 inches. U.S. Virgin Islands...1 to 3 inches, isolated 4 inches.

This rainfall may cause life-threatening flash floods.

WIND: [TOP] Tropical storm conditions are occurring in portions of the tropical storm warning area in the Lesser Antilles and these conditions are expected to subside later today. Tropical storm conditions are expected and hurricane conditions are possible in Puerto Rico on Wednesday and in portions of the Dominican Republic late Wednesday and Thursday.

SURF: [TOP] Swells generated by Dorian are affecting portions of the Lesser Antilles and they should continue during the next several hours. Swells are expected to increase along the southern coasts of Puerto Rico and Hispaniola on Wednesday and they could cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

At 1100 AM AST (1500 UTC), the center of Tropical Storm Dorian was located by data from an Air Force Reserve reconnaissance aircraft and the Martinique radar near latitude 14.2 North, longitude 61.8 West. Dorian is moving toward the west-northwest near 13 mph (20 km/h), and this motion is expected to continue through tonight, followed by a turn toward the northwest on Wednesday. On the forecast track, the center of Dorian will move across the eastern and northeastern Caribbean Sea during the next few days, passing near or south of Puerto Rico on Wednesday, move near or over eastern Hispaniola Wednesday night, and move north of Hispaniola on Thursday. On Thursday night and Friday, the center of Dorian is forecast to move near the Turks and Caicos and southeastern Bahamas.

Maximum sustained winds remain near 50 mph (85 km/h) with higher gusts. Slow strengthening is forecast during the next 48 hours, and Dorian is forecast to be near hurricane strength when it moves close to Puerto Rico and eastern Hispaniola.

Tropical-storm-force winds extend outward up to 45 miles (75 km) from the center.

The estimated minimum central pressure is 1005 mb (29.68 inches).

Dorian moved directly across the center of St. Lucia around 1000 UTC, which resulted in a significant disruption of the small inner-core wind field. An Air Force Reserve reconnaissance aircraft had difficulty identifying a clear-cut center and radar data from Martinique indicates that the mid-level circulation has also been disrupted somewhat. Having said that, the overall appearance of the cyclone in both satellite and radar imagery has improved since this time yesterday, although a pronounced dry slot is now evident in the southeastern quadrant of the circulation. The initial intensity of 45 kt is being maintained based on aircraft flight-level and SFMR surface wind data.

The initial motion remains west-northwestward or 295/11 kt. There is still no significant change to the previous forecast track or reasoning. Although the inner-core wind field and low-level center have been disrupted, the overall circulation envelope has remained intact and is expected to move west-northwestward to northwestward for the next 36-48 hours toward a break in the subtropical ridge located well north of Dorian. The mid- to upper-level low currently located east of the Bahamas that has weakened the ridge is forecast to gradually weaken while digging southeastward across the central Bahamas and toward central Cuba over the next 3-4 days, resulting in Dorian turning northwestward on day 3 before turning back toward the west-northwest on days 4 and 5. How quickly the west-northwestward turn occurs will depend heavily on the evolution of the upper-low. For now, the previous forecast track remains unchanged other than to push out the track a little northeastward at 48 and 72 hours. The NHC model guidance remains tightly packed and in good agreement on this scenario, and the new forecast track lies very close to an average of the various consensus track models. Users are reminded not to focus on the details of the extended track forecast as the average 5-day track error is around 200 miles.

Dry air continues to plague Dorian, and interaction with the mountainous terrain of St. Lucia will likely hinder significant development in the short term. However, the models continue to indicate that the upper-level flow pattern and shear conditions are expected to remain favorable for strengthening throughout the forecast period, so it is uncertain why the dynamical models are not showing more development and strengthening when compared to the more robust statistical SHIPS intensity models, especially at days 4 and 5 when Dorian will be moving over SSTs greater than 29 deg C and into a fairly moist environment. For now, the official intensity forecast remains basically midway between the stronger SHIPS model and the much weaker global and regional models. Given the large spread in the guidance, there is lower than normal confidence in the intensity forecast, especially on days 4 an 5.

Corrected southeastward to southwestward motion in third paragraph

Dorian moved directly across the center of St. Lucia around 1000 UTC, which resulted in a significant disruption of the small inner-core wind field. An Air Force Reserve reconnaissance aircraft had difficulty identifying a clear-cut center and radar data from Martinique indicates that the mid-level circulation has also been disrupted somewhat. Having said that, the overall appearance of the cyclone in both satellite and radar imagery has improved since this time yesterday, although a pronounced dry slot is now evident in the southeastern quadrant of the circulation. The initial intensity of 45 kt is being maintained based on aircraft flight-level and SFMR surface wind data.

The initial motion remains west-northwestward or 295/11 kt. There is still no significant change to the previous forecast track or reasoning. Although the inner-core wind field and low-level center have been disrupted, the overall circulation envelope has remained intact and is expected to move west-northwestward to northwestward for the next 36-48 hours toward a break in the subtropical ridge located well north of Dorian. The mid- to upper-level low currently located east of the Bahamas that has weakened the ridge is forecast to gradually weaken while digging southwestward across the central Bahamas and toward central Cuba over the next 3-4 days, resulting in Dorian turning northwestward on day 3 before turning back toward the west-northwest on days 4 and 5. How quickly the west-northwestward turn occurs will depend heavily on the evolution of the upper-low. For now, the previous forecast track remains unchanged other than to push out the track a little northeastward at 48 and 72 hours. The NHC model guidance remains tightly packed and in good agreement on this scenario, and the new forecast track lies very close to an average of the various consensus track models. Users are reminded not to focus on the details of the extended track forecast as the average 5-day track error is around 200 miles.

Dry air continues to plague Dorian, and interaction with the mountainous terrain of St. Lucia will likely hinder significant development in the short term. However, the models continue to indicate that the upper-level flow pattern and shear conditions are expected to remain favorable for strengthening throughout the forecast period, so it is uncertain why the dynamical models are not showing more development and strengthening when compared to the more robust statistical SHIPS intensity models, especially at days 4 and 5 when Dorian will be moving over SSTs greater than 29 deg C and into a fairly moist environment. For now, the official intensity forecast remains basically midway between the stronger SHIPS model and the much weaker global and regional models. Given the large spread in the guidance, there is lower than normal confidence in the intensity forecast, especially on days 4 an 5.