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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1152Z Jan 29, 2015)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
652 AM EST THU JAN 29 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. BROAD POLAR
TROUGH ACROSS THE WESTERN NORTH ATLANTIC SUSTAINS A SURFACE FRONT
THAT TRAILS ACROSS NORTHERN HISPANIOLA TO THE NORTHWEST CARIBBEAN.
FURTHERMORE...UNDER INFLUENCE OF THE DEEP POLAR TROUGH PATTERN TO
THE NORTH...AN INDUCED/ INVERTED TROUGH NOW EXTENDS OVER THE
EASTERN CARIBBEAN ALONG 63W/64W. ALSO...A SHEAR LINE EXTENDS
ACROSS EASTERN HISPANIOLA TO THE SOUTHERN CARIBBEAN. MOST ACTIVE
CONVECTION IS DEVELOPING IN ASSOCIATION WITH THE SURFACE FRONT AS
IT MEANDERS ALONG THE NORTH COAST OF HISPANIOLA.

UPPER LEVEL TROUGH IS EXPECTED TO PULL AWAY THROUGH FRIDAY
MORNING. ON ITS WAKE...A RIDGE IS TO GRADUALLY ESTABLISH OVER
NORTHERN SOUTH AMERICA/CARIBBEAN TO THE GREATER ANTILLES-THE
BAHAMAS. AS THE RIDGE BUILDS...TRADE WINDS CAP IS TO GRADUALLY
STRENGTHEN THROUGH MIDDAY ON FRIDAY. THIS IS TO THEN HOLD THROUGH
THE WEEKEND/EARLY NEXT WEEK. BEST CHANCE FOR CONVECTION MIGHT BE
TODAY-EARLY FRIDAY MORNING AS THE BASE OF THE MID LEVEL TROUGH AND
A WEEK CYCLONIC MAXIMA GRAZE PUERTO RICO/NORTHERN VI. AT LOW
LEVELS...SURFACE FRONT IS EXPECTED TO STALL FAR TO THE NORTH...AND
GRADUALLY WEAKEN/FRONTOLIZE DURING THE WEEKEND. SHEAR LINE IS TO
MEANDER OVER THE FORECAST AREA DURING THE NEXT COUPLE OF DAYS. BUT
LACKING UPPER LEVEL SUPPORT IT IS NOT EXPECTED TO TRIGGER
SIGNIFICANT CONVECTION. PER THE HIGH RESOLUTION MODELS...IT LOOKS
LIKE MEASURABLE RAINFALL AMOUNTS ARE TO CONFINE TO THE
CENTRAL/WESTERN PORTIONS OF THE CORDILLERA OVER PUERTO RICO...WITH
LIGHT CONVECTION POSSIBLE ALONG THE NORTH COAST AS THE OCCASIONAL
TRADE WIND SHOWER STREAMS ACROSS THE FORECAST AREA.

ANOTHER FRONT IS TO CLEAR THE EASTERN SEABOARD OF THE USA EARLY ON
FRIDAY...BUT THIS IS TO STALL FAR TO THE NORTH. BUILDING POLAR
RIDGE TO THE WEST IS TO THEN SUSTAIN ANOTHER SHEAR LINE ACROSS THE
FORECAST AREA LATER ON SATURDAY...BUT THROUGH MIDDAY ON SUNDAY IT
IS TO CONTINUE FARTHER EAST AND SOUTH ACROSS THE FRENCH ISLES AS
BROAD RIDGE SETTLES TO THE NORTH. BRISK NORTHEASTERLY TRADES ARE
TO ACCOMPANY THIS FEATURE...WITH WINDY CONDITIONS LIKELY TO
PERSIST THROUGH MONDAY EVENING/EARLY TUESDAY MORNING. GLOBAL
MODELS GENERALLY AGREE ON POTENTIAL FOR SCATTERED SHOWERS TO
ACCOMPANY THIS FEATURE AS IT ENTERS PUERTO RICO LATER ON
SATURDAY...WITH BOTH EUROPEAN MODELS SHOWING A SOMEWHAT MORE
ACTIVE PATTERN THAN WHAT THE GFS SUGGESTS.

JN BAPTISTE...MS (SAINT LUCIA)
NANDA...MDS (SURINAME)
DAVISON...WPC (USA)