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FXCA20 KWBC 021249
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
849 AM EDT THU NOV 02 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI NOV 02/12UTC:
THE PREVAILING RAINFALL PATTERN THROUGH SUNDAY IS FORECAST TO BE
SIMILAR EACH DAY...BUT A SFC TROUGH COULD CHANGE THE LOCAL PATTERN
FROM LATE SUNDAY INTO TUESDAY...ESPECIALLY FOR THE USVI. FROM
TODAY THROUGH SUNDAY...GENERALLY EASTERLY WINDS WOULD CAUSE
PASSING SHOWERS TO AFFECT THE USVI AND EASTERN PR...THEN SOME
AFTERNOON CONVECTION IS EXPECTED ACROSS WESTERN PR IN THE
AFTERNOONS. THAT SAID...THE MODEL GUIDANCE IS SUGGESTING MODEST
RAINFALL ACCUMULATIONS ACROSS WESTERN PR EACH
AFTERNOON...SUGGESTING UNDER A HALF AN INCH OF RAIN...THOUGH
SUNDAY INTO MONDAY COULD HAVE OVER A HALF AN INCH OF RAIN. EASTERN
PR IS FORECAST TO OBSERVE BETWEEN 0.5 TO 1 INCH OR SO OF RAIN EACH
DAY...GENERALLY ACROSS AREAS IN AND AROUND THE LUQUILLO MOUNTAIN
RANGE...WHILE THE USVI ARE FORECAST BETWEEN 0.1 AND 0.25 INCHES OF
RAIN EACH DAY THROUGH SUNDAY. HOWEVER...A CHANGE IN THE WIND
PATTERN AND INCREASE IN INSTABILITY LATE SUNDAY INTO EARLY TUESDAY
COULD CAUSE HIGHER RAINFALL AMOUNTS ACROSS THE USVI AND EASTERN
PR...AS A POSSIBLE SFC TROUGH DEVELOPS VERY CLOSE TO PR/USVI.
IN THE UPPER LEVELS...A HIGH PRESSURE IS CENTERED BETWEEN HAITI
AND CUBA AND A TUTT LOW OVER THE CENTRAL LESSER ANTILLES. THIS
SETUP PUTS PR/USVI IN THE SUBSIDENT SIDE OF THE TUTT AND THEREFORE
THE THUNDERSTORM POTENTIAL IS REDUCED FOR THE NEXT FEW
DAYS...WHICH COULD BE PART OF THE REASON WHY THE AFTERNOON
CONVECTION OVER WESTERN PR IS NOT EXPECTED TO BE
IMPRESSIVE...WHILE THE ADVECTIVE RAINFALL PATTERN COULD BE
SIGNIFICANT ACROSS EASTERN AND NORTHEASTERN PR. IT IS NOT UNTIL
LATE IN THE WEEKEND AND EARLY NEXT WEEK WHEN THE INSTABILITY WILL
INCREASE ACROSS PR/USVI...THOUGH THE LATEST GUIDANCE SUGGESTS THE
CHANCES OF THUNDERSTORMS WILL BE BETTER ACROSS THE USVI AND
NORTHERN LEEWARD ISLANDS. A MID LEVEL HIGH PRESSURE OVER THE
CENTRAL ATLANTIC WILL EXTEND INTO THE NORTHEASTERN CARIBBEAN INTO
THE WEEKEND...BUT AN MID LEVEL TROUGH WILL APPROACH THE
NORTHEASTERN CARIBBEAN BY EARLY SUNDAY...CAUSING INSTABILITY TO
INCREASE INTO EARLY NEXT WEEK. A SURFACE HIGH PRESSURE ACROSS THE
CENTRAL ATLANTIC WILL KEEP THE LOCAL WINDS MOSTLY FROM THE EAST
THROUGH THE WEEKEND...BUT IT WILL SLOWLY MOVE EAST AS A SFC LOW
DEVELOPS ACROSS THE WEST CENTRAL ATLANTIC. THIS SFC LOW WILL HAVE
AN ASSOCIATED TROUGH THAT COULD EXTEND INTO THE NORTHEASTERN
CARIBBEAN AND COINCIDE WITH THE MID LEVEL TROUGH...AND THEREFORE
BE A DRIVER OF INSTABILITY AND THUNDERSTORM POTENTIAL FOR THE
USVI...IF IT STAYS EAST OF MAINLAND PR AS THE MODELS ARE
SUGGESTING.
THE 5-DAY RAINFALL FORECAST SUGGESTS THAT NORTHEASTERN PR COULD
HAVE OVER 3 INCHES OF RAIN...WHILE WESTERN PR AS WELL AS THE USVI
COULD HAVE BETWEEN 1.0 AND 1.5 INCHES. LATE SUNDAY INTO EARLY
TUESDAY IS EXPECTED TO BE THE RAINIEST PERIOD FOR THE USVI AS THE
SFC AND MID LEVEL TROUGHS APPROACH THE AREA.
ALAMO...WPC (USA)
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