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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1140Z Oct 27, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
740 AM EDT MON OCT 27 2014

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. A LARGE POLAR
TROUGH EXTENDS FO THE NORTH OF THE ISLANDS ALONG 30N 68W...25N
70W...TURKS AND CAICOS. THE TROUGH IS SUSTAINING A SURFACE FRONT
THAT EXTENDS NORTH OF THE ISLANDS...WITH MOST CONVECTION REMAINING
OVER AND NORTH OF HISPANIOLA. ALSO AT UPPER LEVELS...A RIDGE
EXTENDS FROM NORTHERN CENTRAL AMERICA INTO THE NORTHERN CARIBBEAN
AND PUERTO RICO. TO THE SOUTHEAST...A TUTT IS SLOWLY RETROGRESSING
JUST WEST OF THE CENTRAL ANTILLES. THE TUTT IS INTERACTING WITH A
TROPICAL WAVE THAT IS ABOUT TO ENTER THE WINDWARD ISLANDS...WITH
MOST OF THE CONVECTION STILL OVER OPEN WATERS OF THE ATLANTIC. THE
RETROGRESSING TUTT HAS ALSO UNDULATED THE ITCZ NORTHWARD...LEADING
TO WIDESPREAD DEEP CONVECTION IN AREAS EAST OF GUADELOUPE AT
50-55W ALONG A TUTT-INDUCED WAVE.

MODELS CONTINUE AGREEING ON A WET TREND SLOWLY ESTABLISHING OVER
THE ISLANDS BY MID-WEEK IN ASSOCIATION WITH RETROGRESSING TUTT AND
TUTT-WAVE INDUCED IN THE TRADES. AFOREMENTIONED POLAR TROUGH IS
FORECAST TO PULL NORTHEASTWARD GRADUALLY STARTING TODAY. THIS WILL
LIMIT THE ADVANCE OF THE SURFACE FRONT CONSTRAINING ITS EFFECTS
MOSTLY TO HISPANIOLA. IN THE MEAN TIME...TUTT OVER THE EASTERN
CARIBBEAN IS FORECAST TO MEANDER NORTHWESTWARD TO CENTER ALONG
PUERTO RICO AND 15N 65W BY TUESDAY EVENING. IT IS TO THEN INTERACT
WITH SHORT WAVE UPPER TROUGH LINGERING TO THE NORTH OF THE ISLANDS
TO EXTEND ACROSS THE VIRGIN ISLANDS AND THE EASTERN CARIBBEAN INTO
EASTERN VENEZUELA BY WEDNESDAY EVENING. AFOREMENTIONED TROPICAL
WAVE WILL LIMIT ITS EFFECTS TO THE SOUTHERN/CENTRAL CARIBBEAN
WHILE TRAILING TUTT-INDUCED WAVE IS EXPECTED TO HAVE A DIRECT
IMPACT ON THE ISLANDS. YET...BY TUESDAY AFTERNOON...MODELS ARE
FORECASTING 10-15KT NORTHEASTERLY TRADES DEVELOPING ACROSS THE
ISLANDS. THESE WINDS SHOULD SET UP A COLD ADVECTIVE PATTERN WITH
SHALLOW CONVECTIVE INSTABILITY DEVELOPING...AND NUMEROUS LIGHT
RAIN SHOWERS ESTABLISHING ACROSS NORTHEASTERN PUERTO RICO INTO
WEDNESDAY MORNING. LARGEST CONVECTIVE INSTABILITY IS FORECAST TO
DEVELOP ACROSS THE VIRGIN ISLANDS AND SOUTHEASTERN PUERTO RICO
DURING WEDNESDAY MORNING...EXTENDING INTO ALL OF PUERTO RICO
DURING THE REST OF THE DAY...SUSTAINING NUMEROUS SHOWERS AND A FEW
THUNDERSTORMS DURING WEDNESDAY AND LIKELY CONTINUING INTO THURSDAY.

GLOBAL MODELS ARE VERY CONSERVATIVE WITH PRECIPITATION. THEY SHOW
CORE OF CONVECTIVE INSTABILITY ASSOCIATED WITH THE TUTT-INDUCED
WAVE AND ASSOCIATED PRECIPITATION MOVING NORTHWESTWARD TO THE
NORTHEAST OF THE LEEWARD ISLANDS. THEY SUGGEST RAINFALL AMOUNTS
PEAKING AT 15MM/DAY ACROSS PUERTO RICO/USVI ON WEDNESDAY AND
THURSDAY. ALTHOUGH IT IS A LITTLE BIT EARLY...IT APPEARS THAT
RAINFALL WITH THIS SYSTEM WILL BE LIMITED. THUS EXPECTING
SCATTERED ACCUMULATIONS OF 05-10MM/DAY AND ISOLATED MAXIMA OF
15-25MM. MOST ACTIVE PERIOD IS EXPECTED ACROSS THE VIRGIN ISLANDS
AND EASTERN PUERTO RICO DURING WEDNESDAY MORNING...WITH LINGERING
BUT WEAKENING SHOWERS AND ISOLATED THUNDERSTORMS AFTERWARDS.

JN BAPTISTE...MS (SAINT LUCIA)
MEDINA...ONAMET (REPUBLICA DOMINICANA)
GALVEZ...WPC (USA)