1. Dorian is expected to bring tropical storm conditions to portions of the Lesser Antilles tonight and Tuesday, where tropical storm watches and warnings are in effect. Hurricane conditions are also possible in portions of the Windward Islands, and a hurricane watch has been issued for St. Lucia. Residents in these areas should refer to advice from local government officials and products from their local meteorological service for additional information.

2. Dorian is expected to produce 3 to 8 inches of rainfall from Martinique to St. Vincent, including Barbados, with isolated totals as high as 10 inches in portions of the northern Windward Islands.

3. The risk of direct impacts from wind and rainfall has increased for Puerto Rico and Hispaniola. Interests in those areas should monitor the progress of Dorian and tropical storm or hurricanewatches will likely be required later today.

4. Any potential impacts from Dorian in the Bahamas and Floridalater this week are highly uncertain, given the potential for the system to interact with the high terrain of Hispaniola.

WHAT'S NEW:

A Hurricane Watch has been issued by the government of St. Lucia for St. Lucia. The government of France has upgraded the Tropical Storm Watch to a Tropical Storm Warning for Martinique.

SUMMARY OF ALERTS:

A Hurricane Watch is in effect for...
- St. Lucia

A Tropical Storm Warning is in effect for...
- Barbados
- Martinique
- St. Lucia
- St. Vincent and the Grenadines

A Tropical Storm Watch is in effect for...
- Dominica
- Grenada and its dependencies
- Saba and St. Eustatius

A Hurricane Watch means that hurricane conditions are possible within the watch area, in this case, within the next 24 hours.

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 Puerto Rico, the Virgin Islands, and Hispaniola should monitor the progress of Dorian as watches for these areas later could be required later today. For storm information specific to your area, please monitor products issued by your national meteorological service.

RAINFALL: Dorian is expected to produce total rain accumulations of 3 to 8 inches in the Windward Islands from Martinique south to St. Vincent, including Barbados. Isolated maximum totals of 10 inches are possible across the northern Windward Islands. Rainfall totals of 1 to 3 inches are expected from the Grenadines, south to Grenada and across Dominica.

WIND: [TOP] Hurricane conditions are possible tonight and early Tuesday within the Hurricane Watch area in the Lesser Antilles. Tropical storm conditions are likely in the warning area by late today. Tropical storm conditions are possible within the tropical storm watch area by tonight or Tuesday.

SURF: [TOP] Swells generated by Dorian will be affecting portions of the Lesser Antilles by late today. These swells 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 near latitude 12.3 North, longitude 57.7 West. Dorian is moving toward the west-northwest near 14 mph (22 km/h) and this motion is expected to continue through Tuesday night, followed by a turn toward the northwest on Wednesday. On the forecast track, the center of Dorian is expected to be near the Windward Islands late today and tonight, and move into the eastern Caribbean Sea on Tuesday. Dorian is expected to pass near or south of Puerto Rico on Wednesday and approach eastern Hispaniola Wednesday night.

Maximum sustained winds are near 60 mph (95 km/h) with higher gusts. Some strengthening is forecast during the next few days, and Dorian could be near hurricane strength when it passes through the northern Windward Islands on Tuesday, and is expected to be a hurricane when it moves near Puerto Rico and eastern Hispaniola.

Dorian is a small tropical cyclone. Tropical-storm-force winds only extend outward up to 45 miles (75 km) from the center.

The estimated minimum central pressure is 1002 mb (29.59 inches).

Satellite imagery indicates that Dorian's convective and outflow pattern have continued to improve, with a narrow poleward outflow channel now apparent in water vapor images. Passive microwave imagery has shown a persistent low-level eye-like feature along with an intermittent mid-level eyewall forming that quickly erodes due to mid-level dry air entrainment. The initial intensity of 50 kt is based on a blend of satellite intensity estimates ranging from 45 kt to 56 kt from TAFB, SAB, and UW-CIMSS ADT and SATCON.

The initial motion is now west-northwestward or 285/12 kt. Dorian is expected to continue moving west-northwestward today through Tuesday night as the cyclone moves around the southwestern periphery of a deep-layer subtropical ridge situated to its north. On Wednesday, Dorian is forecast to turn northwestward toward a weakness in the ridge, which could allow the cyclone to pass near or between western Puerto Rico and the eastern Dominican Republic. By late Thursday and Friday, all of the model guidance indicates that the ridge will build back as an upper-level trough/low weakens and lifts out to the north, which should result in Dorian turning back toward the west-northwest in the vicinity of the Bahamas. The new NHC track forecast has been nudged slightly to the right or north of the previous one and lies close to the tightly clustered consensus models HCCA, FSSE, TVCN, and TVCX.

The intensity forecast is less straight-forward than the track forecast. Environmental conditions, except for the abundance of dry mid-level air surrounding and occasionally being entrained into Dorian's inner-core region, would favor at least steady strengthening due to very low vertical wind shear, SSTs of at least 29C, and the small overall circulation and inner-core wind field. The recent development of a poleward outflow channel and possible development of an equatorward channel would also support strengthening. However, until Dorian closes off a solid eyewall, only slow strengthening is likely. Anticipating when an eye will form is challenging, but Dorian could be a hurricane by the time it reaches the Windward Islands. The intensity forecast has been adjusted upward form the previous advisory, but is not as high as the statistical-dynamical SHIPS and LGEM intensity models. Interaction with Hispaniola and possibly Puerto Rico should result in some weakening in 72-96 hours, followed by restrengthening on day 5 when Dorian will be moving over the very warm waters in the Bahamas in low shear conditions. Given the unknown degree of interaction with Hispaniola, the intensity forecast at days 4 and 5 is of very low confidence.