936
FXCA20 KWBC 111238
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
838 AM EDT WED OCT 11 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI OCT 11/12UTC:
A WEAK SURFACE HIGH PRESSURE TO THE NORTH OF PR/USVI WILL PROMOTE
EASTERLY WINDS THROUGH THURSDAY. A SURFACE LOW PRESSURE IS
FORECAST TO MOVE INTO THE WESTERN ATLANTIC TO THE NORTH OF THE
BAHAMAS ON THURSDAY...AND MOVE EAST NEAR BERMUDA BY FRIDAY...WHICH
COULD BRING A SURFACE TROUGH OVER THE AREA AND INFLUENCE THE LOCAL
WINDS...MAKING THEM LIGHT AND SOUTHEASTERLY ON FRIDAY. THE LOCAL
WINDS...HOWEVER...COULD BECOME VERY LIGHT AND VARIABLE BY LATE
FRIDAY AS THE SURFACE TROUGH MOVES OVER THE AREA AND A FRONTAL
BOUNDARY MOVES SOUTH BUT REMAINS NORTH OF 20N. THE LOCAL WINDS
WILL REMAIN FAIRLY LIGHT...AROUND 10KT OR LESS BY SUNDAY INTO
MONDAY BUT BECOME MORE SOUTHERLY. HIGH PRESSURE SYSTEMS IN THE MID
AND UPPER LEVELS WILL PERSIST OVER THE AREA OVER THE NEXT COUPLE
OF DAYS...AND A STRONG TRADE WIND INVERSION WILL PREVAIL OVER
PR/USVI TODAY...THOUGH WEAKENING ON THURSDAY. THE AVAILABLE
MOISTURE IS MUCH BELOW AVERAGE TODAY...BUT IS EXPECTED TO
GRADUALLY INCREASE UNTIL THURSDAY. WITH PRECIPITABLE WATER GOING
FROM AROUND 1.4 INCHES CURRENTLY TO ALMOST 2 INCHES BY THURSDAY
MORNING. IT IS EXPECTED FOR THE PRECIPITABLE WATER TO PEAK ON
THURSDAY...THEN REMAIN BETWEEN 1.7 AND 1.9 INCHES OR SO FOR THE
REST OF THE WORKWEEK INTO THE WEEKEND. EVEN THOUGH MOISTURE
INCREASES ON THURSDAY...AND REMAINS NEAR NORMAL INTO THE
WEEKEND...THE INSTABILITY PARAMETERS ARE NOT PARTICULARLY
SUGGESTIVE OF STRONG STORMS. THE MODELS STILL FORECAST THE 500MB
TEMPS TO BE VERY WARM...LAPSE RATES REMAIN WEAK...AND THE EGDI
ALGORITHM ONCE AGAIN DOES NOT SUGGEST MUCH...EXCEPT A CHANCE OF
VERY ISOLATED THUNDERSTORMS ON THURSDAY AFTERNOON.
GIVEN THE BELOW NORMAL MOISTURE AND THE STRONG TRADE WIND
INVERSION EXPECTED TODAY...THE FORECAST RAINFALL TODAY IS VERY
LIMITED...MAINLY TO OCCUR OVER THE WESTERN INTERIOR TO WESTERN
PR...WITH MAX VALUES OF UNDER HALF AN INCH...WHILE THE USVI AND
EASTERN PR COULD RECEIVE AROUND A TENTH OF AN INCH OR LESS IN
BRIEF SHOWERS. THURSDAY LOOKS LIKE IT COULD HAVE A BIT MORE SHOWER
ACTIVITY CONSIDERING THE INCREASE IN MOISTURE...AND THEREFORE OVER
AN INCH OF RAIN IS FORECAST ACROSS NORTHWESTERN PR...WHILE UNDER A
HALF AN INCH IS FORECAST OVER THE LUQUILLO MOUNTAIN RANGE...AND A
FEW HUNDREDTHS ELSEWHERE. FOR FRIDAY INTO THE WEEKEND...WITH THE
APPROACHING SURFACE TROUGH AND LIGHT WINDS...THE MAX VALUES ARE
FORECAST TO BE UNDER A HALF AN INCH. THE MOST SIGNIFICANT RAINFALL
ON FRIDAY IS FORECAST TO BE ACROSS THE WESTERN INTERIOR OF PR...ON
SATURDAY ACROSS THE WESTERN TO NORTHWESTERN PR...AND ON SUNDAY
ACROSS THE NORTHERN HALF OF PR...DUE TO THE SOUTHERLY WINDS THAT
ARE EXPECTED BY THEN. THE USVI IS FORECAST TO RECEIVE LITTLE TO NO
RAIN FROM FRIDAY ONWARD...WITH MAX VALUES FORECAST TO BE UNDER A
TENTH OF AN INCH ON FRIDAY...NO ACCUMULATIONS TO A FEW HUNDREDTHS
ON SATURDAY...WHILE SUNDAY COULD HAVE OVER A TENTH OF AN INCH BUT
LESS THAN A QUARTER OF AN INCH OF RAIN.
THE 5-DAY RAINFALL TOTAL IS FORECAST TO BE AROUND 2 INCHES FOR THE
NORTHWESTERN SECTIONS OF PR...NEAR 0.5 INCHES FOR THE NORTHEASTERN
SECTIONS...AND 0.10 TO 0.50 INCHES ACROSS VIEQUES..CULEBRA...AND
THE USVI.
ALAMO...WPC (USA)
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