Barbados Meteorological Services
Charnocks ChCh
Weather Discussion
http://www.BarbadosWeather.org

Initial to 4 days discussion based on Satellite imagery,BMS Radar composite,S.P.I.E products,GEM, GFS, WW3, UKMET and BMS WRF modeling, surface and upper air observations, Satellite derived products.

DATE: 20170920 PERIOD: Morning

Wayne McGeary 4 Morning ...SPECIAL FEATURES...

Showers and thunderstorms continue near a low pressure area associated with the remnants of Lee located about 1000 miles east of the Leeward Islands. While this system is producing gale-force winds, the associated thunderstorm activity has become less concentrated during the past few hours. Although the enviromental conditions are marginal, only a small increase in the overall organization of the thunderstorms would result in the regeneration of Lee. This low is expected to move northward over the central
Atlantic Ocean.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...70 percent.

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...ATLANTIC TROPICAL WAVES...
A tropical wave is in the E Atlc with axis extending from 18N26W to 06N27W, moving west at 20 kt. The wave is mainly within a region of abundant low to middle level moisture as shown by CIRA TPW imagery. However, enhanced IR imagery show intrusion of Saharan dry air and dust to the W environment of the wave. This is limiting the convection to scattered moderate from 07N to 14N between 24W and 30W.

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Although the dangerous Category 5 Hurricane Maria continued its west-northwestward motion away from the island chain overnight, feeder bands associated with this system still generated moderate to heavy showers, periods of rain, thunderstorms and gusty winds mainly over the Leeward islands. However, as the night progressed, there was some improvement over the southern Leewards. On the other hand, only occasional showers were reported over the Windward islands, despite some cloudiness persisting over most of these islands throughout the night.

THE FLOOD-WATCH WAS DISCONTINUED AT MIDNIGHT.

Winds across the region generally ranged from 10 to 18 knots with higher gusts only being reported over the Leeward islands. Furthermore, seas also remained rough to very rough across these islands, with swells peaking near 5.0m. Meanwhile over the Windward islands, swells ranged from 1.5m to 3.0m.

Further south, occasional cloudiness with a few isolated pockets of convection were observed over the region.
...SPECIAL FEATURES...

500 AM AST Wed Sep 20 2017

...CORE OF EXTREMELY DANGEROUS HURRICANE MARIA NEARING PUERTO
RICO...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
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LOCATION...17.9N 65.6W
ABOUT 15 MI...25 KM SSW OF VIEQUES
ABOUT 50 MI...75 KM SE OF SAN JUAN PUERTO RICO
MAXIMUM SUSTAINED WINDS...155 MPH...250 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...917 MB...27.08 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The government of France has discontinued the Tropical Storm
Warning for Guadeloupe.

The government of the Bahamas has issued a Hurricane Warning for
the Turks and Caicos Islands and the Southeastern Bahamas.

The government of the Netherlands has discontinued the Hurricane
Watch for Saba and St. Eustatius.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Hurricane Warning is in effect for...
* U.S. Virgin Islands
* British Virgin Islands
* Puerto Rico, Culebra, and Vieques
* Dominican Republic from Cabo Engano to Puerto Plata
* Turks and Caicos Islands and the Southeastern Bahamas

A Tropical Storm Warning is in effect for...
* Saba
* St. Maarten
* Dominican Republic west of Puerto Plata to the northern border of
the Dominican Republic and Haiti
* Dominican Republic west of Cabo Engano to Punta Palenque

A Hurricane Watch is in effect for...
* St. Maarten
* St. Martin and St. Barthelemy
* Dominican Republic from Isla Saona to Cabo Engano

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Puerto Rico and the Virgin Islands continued to feel the devastating effects of Hurricane Maria overnight, as the eye of this system passed awfully close to the US Virgin Islands. Subsequently, heavy to violent showers, widespread periods of moderated to heavy rain, scattered thunderstorms and hurricane force winds were all experienced over those islands. By day break the eye of Maria was on the doorstep of Puerto Rico.

Over the Western Caribbean, the combination of an upper level trough and monsoon activity, generated some moderate to strong convection across the Central American region. Meanwhile elsewhere, a few scattered showers were reported. As the centre of Hurricane Maria continues its west-northwestward track today, the northern Leewards will continue to experience pockets of moderate to heavy showers, rain, isolated thunderstorms and gusty winds initially with an improvement in weather conditions as the day progresses. Meanwhile, some moisture will linger over Barbados the Windward islands, as a moist southerly to southeasterly surface to mid level flow continues to advect moisture over the area today through Friday. As a result, occasional scattered showers will be likely during this time, with the slight chance of an isolated cell. As Maria drifts further away from the Eastern Caribbean, the Leewards too will experience similar conditions to the Windward islands for the remainder of the week.

The remnants Tropical Depression "LEE", are expected to merge with a low to mid level trough in the central Atlantic over the next few days and eventually propagate westward by late Friday. Despite this, a 60% to 70% chance of re-development over the next 2 to 5 days has been attached to this feature. Nevertheless, current analysis shows this merged feature weakening as it traverses the region over the weekend. A Tropical wave now along 27W is the next feature to approach the region late Saturday into Sunday, bringing another round of possible scattered shower and thunderstorm activity to the region. Major catastrophic Hurricane Maria is expected to continue its west-northwesterly track through tonight. On its present track, the eye of Maria will move over Puerto Rico today, before approaching the Dominican Republic tonight. Some fluctuations in intensity are likely during the next day or two however, forecasts still predict Maria to remain an extremely dangerous Category 4 or 5 hurricane while it moves over Puerto Rico. Life-threatening winds, storm surge accompanied by large and destructive waves, significant rainfall which will cause life-threatening flash floods, mudslides and adverse surf conditions are expected within the watch and warning areas.


KEY MESSAGES:

1. Maria's core will make landfall over Puerto Rico within the
next couple of hours, bringing life-threatening wind, storm surge,
and rainfall impacts to the island. Everyone in Puerto Rico should
follow advice from local officials to avoid life-threatening
flooding from storm surge and rainfall.

2. Wind speeds atop and on the windward sides of hills and mountains
and on high-rise buildings could be much stronger than the
near-surface winds indicated in this advisory.

3. A Hurricane Warning is also in effect for the Virgin Islands,
the northern coast of the Dominican Republic, the Turks and
Caicos Islands and the southeastern Bahamas, where Maria is expected
to bring dangerous wind, storm surge, and heavy rainfall.

FORECAST POSITIONS AND MAX WINDS

INIT 20/0900Z 17.9N 65.6W 135 KT 155 MPH
12H 20/1800Z 18.6N 66.7W 125 KT 145 MPH...INLAND
24H 21/0600Z 19.5N 68.2W 120 KT 140 MPH
36H 21/1800Z 20.5N 69.4W 120 KT 140 MPH
48H 22/0600Z 21.5N 70.5W 115 KT 130 MPH
72H 23/0600Z 24.2N 72.0W 105 KT 120 MPH
96H 24/0600Z 27.3N 73.0W 100 KT 115 MPH
120H 25/0600Z 30.5N 73.0W 85 KT 100 MPH