493
FXCA20 KWBC 301250
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
750 AM EST THU NOV 30 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI NOV 30/12UTC:
GENERALLY FAIR WEATHER WITH ONLY BRIEF SHOWERS ARE FORECAST ACROSS
EASTERN PR AND THE USVI FOR THE NEXT 5 DAYS. AT TIMES...PORTIONS
OF WEST TO SOUTHWESTERN PR COULD HAVE SOME RAINFALL...THOUGH THE
CONVECTION IS EXPECTED TO BE SHALLOW AND THE AMOUNTS OF RAIN
RELATIVELY MODEST. THE AVAILABLE MOISTURE IS FORECAST TO BE BE
BELOW NORMAL THROUGH FRIDAY...THEN MOISTURE WILL BE GENERALLY NEAR
NORMAL THROUGH THE WEEKEND INTO EARLY MONDAY.
A SURFACE HIGH PRESSURE MAKING ITS WAY INTO THE WESTERN ATLANTIC
TODAY WILL CONTINUE TO MOVE EAST OVER THE NEXT FEW
DAYS...DOMINATING THE GENERAL WIND FLOW AND IS EXPECTED TO BE OVER
THE CENTRAL ATLANTIC BY THIS WEEKEND. THERE IS A WEAKENING FRONTAL
BOUNDARY TO THE NORTH OF THE LOCAL ISLANDS...WHICH IS EXPECTED TO
LOSE ITS DEFINITION BY FRIDAY...THEN THE MOISTURE ASSOCIATED WITH
THE REMNANTS OF THE FRONTAL BOUNDARY WILL BE PUSHED SOUTH AND OVER
THE LOCAL ISLANDS ON SATURDAY...AS THE SFC HIGH PRESSURE MOVES
EAST INTO THE CENTRAL ATLANTIC. THIS IS THE MAIN REASON FOR THE
EXPECTED INCREASE IN MOISTURE ON SATURDAY. IN THE MID LEVELS...A
HIGH PRESSURE WILL CONTINUE TO DOMINATE AND PROMOTE STABILITY OVER
THE CARIBBEAN REGION THROUGH THE REST OF THE WORKWEEK AND INTO THE
WEEKEND. IN THE UPPER LEVELS...A RIDGE WILL PERSIST OVER THE
NORTHEASTERN CARIBBEAN TODAY...BUT A WEAK TROUGH WILL DEVELOP
ACROSS THE NORTHEAST CARIBBEAN ON FRIDAY...AS IT MOVES EAST AND
AMPLIFIES OVER THE LEEWARDS THIS WEEKEND. NO SIGNIFICANT IMPACT IS
EXPECTED ACROSS PR/USVI AS THE AXIS WOULD BE TO THE EAST OF THE
LOCAL ISLANDS AND THERE IS A STRONG MID LEVEL HIGH PRESSURE.
THE EGDI FORECAST ALGORITHM IS CONTINUES TO SUGGEST THAT SHALLOW
CONVECTION IS POSSIBLE AND THERE IS NO INDICATION THAT
THUNDERSTORMS ARE TO BE EXPECTED OVER THE NEXT 5 DAYS. THIS IS
CONSISTENT WITH THE EXPECTED IMPACT FROM A STRONG MID LEVEL HIGH
PRESSURE DOMINATING THE AREA. THE TWIN ALGORITHM CONTINUES TO
SUGGEST THAT A TRADE WIND INVERSION WILL BE PRESENT AT AROUND THE
900-800 HPA LEVEL THROUGH SATURDAY...WITH THE INVERSION POSSIBLY
ERODING ON SUNDAY. EVEN THOUGH THE RAINFALL PATTERN IS EXPECTED TO
BE SOMEWHAT SIMILAR EACH DAY OVER THE FORECAST PERIOD...THE AMOUNT
OF RAIN MAY VARY SLIGHTLY DUE TO SLIGHT CHANGES IN WIND DIRECTION
AND AN INCREASE IN AVAILABLE MOISTURE THIS WEEKEND. THE
PRECIPITABLE WATER IS FORECAST TO BE GENERALLY BETWEEN 1.1 AND 1.5
INCHES THROUGH FRIDAY...THEN AN INCREASE IN MOISTURE COULD OCCUR
LATE SATURDAY THROUGH SUNDAY...WITH PRECIPITABLE WATER RANGING
FROM 1.5 TO ABOUT 1.7 INCHES...THOUGH BRIEF DRY PATCH IS POSSIBLE
SUNDAY NIGHT INTO MONDAY.
OVER THE NEXT 5 DAYS...DAILY RAINFALL BETWEEN 0.25 AND 0.5 INCHES
ARE FORECAST FOR PORTIONS AROUND THE LUQUILLO MOUNTAIN
RANGE...WILE HUNDREDTHS OF AN INCH ARE FORECAST FOR THE USVI. THE
5-DAY TOTAL RAINFALL FORECAST SUGGESTS THAT EASTERN AND
NORTHEASTERN PUERTO RICO WOULD HAVE AROUND OR JUST UNDER 1.5
INCHES OF RAIN. SOME SECTIONS OF SOUTHWESTERN PR ARE FORECAST
BETWEEN 0.25 AND 0.5 INCHES...AND THE USVI...VIEQUES AND CULEBRA
ARE ALSO FORECAST BETWEEN 0.25 AND 0.50 INCHES.
ALAMO...WPC (USA)
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