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FXCA20 KWBC 311241
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
841 AM EDT THU AUG 31 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI AUG 31/12UTC:
EASTERLY WINDS ARE FORECAST TO PREVAIL INTO FRIDAY...WITH A
POSSIBLE GRADUAL SHIFT TO SOUTHEASTERLY SATURDAY INTO SUNDAY. THIS
SHIFT IN WINDS MAY BE INFLUENCED BY A TROPICAL WAVE THAT IS MOVING
INTO THE LOCAL ISLANDS STARTING LATE FRIDAY AND THE EVENTUAL TRACK
OF TROPICAL STORM IDALIA...WHICH COULD BE WELL TO THE NORTH OF
PR/USVI THIS WEEKEND ACCORDING TO THE NHC FORECAST TRACK.
PRECIPITABLE WATER IS EXPECTED TO BE NEAR NORMAL FOR THE NEXT FEW
DAYS...BUT DRIER AIR MAY MOVE IN THIS WEEKEND AS THE CONCENTRATION
OF SAHARAN DUST INCREASES. THEREAFTER...ACCORDING TO THE GLOBAL
MODELS...MOISTURE WILL INCREASE ON MONDAY INTO TUESDAY AS MOISTURE
FROM A TROPICAL WAVE OVER THE SOUTH CARIBBEAN GETS PULLED NORTH
AND OVER THE LOCAL ISLANDS.
THE EXPECTED RAINFALL PATTERN OVER THE NEXT SEVERAL DAYS IS STILL
EXPECTED TO BE TYPICAL. THEREFORE LOCALLY INDUCED SHOWER AND
THUNDERSTORM ACTIVITY ACROSS WESTERN PR IN THE AFTERNOONS...AND
TRADE WIND SHOWER ACTIVITY IN THE MORNING AND EVENING HOURS ACROSS
THE USVI AND EASTERN PR ARE EXPECTED OVER THE NEXT SEVERAL DAYS.
THE MODEL GUIDANCE IS SUGGESTING MORE RAINFALL TODAY THAT IT WAS
SUGGESTING THE PAST FEW DAYS...THE THUNDERSTORM ACTIVITY FORECAST
THIS AFTERNOON...ACCORDING TO THE LATEST GUIDANCE...COULD PRODUCE
OVER 2 INCHES OF RAIN ACROSS THE NORTHWESTERN QUADRANT OF
PR...WHILE NORTHEASTERN PR AND THE USVI IS FORECAST TO OBSERVE
UNDER A QUARTER OF AN INCH OF RAIN. ONE THING TO NOTE IS THAT SOME
OF THE HIGH RESOLUTION GUIDANCE WAS SUGGESTING UP TO 3 INCHES OF
RAIN ACROSS ISOLATED AREAS OF W/NW PR FOR THIS AFTERNOON.
A DECREASE IN SHOWER ACTIVITY IS EXPECTED...PARTICULARLY DURING
THE WEEKEND AS SAHARAN DUST CONCENTRATION INCREASES. THE JURY IS
STILL OUT ON JUST HOW MUCH MOISTURE AND RAIN WILL PRODUCE THE
POSSIBLE INCREASE IN MOISTURE EARLY NEXT WEEK. THERE IS STILL TOO
MUCH UNCERTAINTY AT THE MOMENT FOR THAT TIME PERIOD. THE 5-DAY
RAIN TOTAL FORECAST SUGGESTS NORTHWESTERN PR IS TO RECEIVE NEAR
3.5 INCHES OF RAIN...AROUND 1.25 INCHES FOR NORTHEASTERN PR...AND
NEAR 0.5 INCHES OF RAIN. THERE IS ALSO A SMALL PORTIONS OF
SOUTHEAST PR THAT COULD RECEIVE OVER 2 INCHES OVER THE NEXT 5
DAYS...BUT THAT WOULD BE DEPENDENT UPON THE EVENTUAL INCREASE IN
MOISTURE ON MONDAY AND TUESDAY...SO CONFIDENCE IS LOW ON THAT.
ALAMO...WPC (USA)
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