991
FXCA20 KWBC 051233
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
832 AM EDT THU OCT 05 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI OCT 05/12UTC:
TROPICAL STORM PHILIPPE IS NOW OVER 450 MILES NORTH OF ST THOMAS
AND CONTINUES TO MOVE NORTH. HOWEVER...THE STORM WILL CONTINUE TO
HAVE AN INFLUENCE ON THE LOCAL WINDS FOR THE NEXT FEW DAYS.
THEREFORE SOUTH TO SOUTHEASTERLY WINDS ARE EXPECTED INTO THE
WEEKEND. ABOVE NORMAL MOISTURE IS EXPECTED OVER PR/USVI TODAY AND
FRIDAY...WITH PRECIPITABLE WATER VALUES OVER 2 INCHES. A TROPICAL
WAVE WILL MOVE INTO THE AREA ON FRIDAY...THEN DRIER AIR...POSSIBLY
WITH SOME SAHARAN DUST...WILL START TO MOVE IN ON SATURDAY AND
PRECIPITABLE WATER TAKES A NOSEDIVE. BY SATURDAY EVENING INTO
SUNDAY THE PRECIPITABLE WATER WILL BE NEAR ONE INCH...WHICH IS
MORE THAN TWO STANDARD DEVIATIONS BELOW NORMAL.
GIVEN THE CURRENT PATTERNS WITH THE SOUTHERLY WIND PULLING UP
MOISTURE AND THE TROPICAL WAVE MOVING IN ON FRIDAY...TODAY AND
FRIDAY ARE EXPECTED TO BE THE DAYS WITH THE MOST RAIN ACROSS
PR/USVI. THERE IS A CHANCE OF THUNDERSTORMS TODAY AND FRIDAY...BUT
THE THUNDERSTORMS ARE NOT EXPECTED TO BE SEVERE...AS THE 500MB
TEMPS ARE RELATIVELY WARM AT AROUND -4C AND THE LAPSE RATES ARE
ALSO RELATIVELY WEAK. IN ADDITION...THERE IS A WEAK UPPER LEVEL
HIGH PRESSURE TO THE NORTH AND EAST OF THE ISLANDS THAT IS SLOWLY
MOVING INTO THE LOCAL ISLANDS BY LATE FRIDAY INTO SATURDAY. AFTER
THE TROPICAL WAVE MOVES THROUGH ON FRIDAY...THE DRIER AIR MOVES IN
ON SATURDAY AND THE SHOWER ACTIVITY IS EXPECTED TO DECREASE
SIGNIFICANTLY ACROSS THE AREA...BUT SUNDAY AND MONDAY ARE EXPECTED
TO BE MUCH DRIER THAN NORMAL...AND THE SHOWER ACTIVITY IS EXPECTED
TO BE VERY LIMITED...IF ANY.
BASED ON THE CURRENT FORECAST...MOST OF THE RAINFALL ACCUMULATIONS
ARE TODAY AND FRIDAY AS DESCRIBED ABOVE...WITH RAINFALL TOTALS
NEAR ONE AND 1.5 INCHES ACROSS THE NORTH COASTAL AND SOUTHWEST
COASTAL SECTIONS OF PR...WHILE THE USVI COULD OBSERVE UNDER A
QUARTER OF AN INCH...FRIDAY IS FORECAST TO HAVE MAX VALUES OF RAIN
OF AROUND AN INCH ACROSS SOUTH AND SOUTHEASTERN PR INTO THE USVI
AS THE TROPICAL WAVE MOVES THROUGH. SATURDAY THROUGH MONDAY WILL
BE DRIER...WITH MAX VALUES OF RAIN EXPECTED TO BE UNDER A QUARTER
OF AN INCH ANYWHERE OVER THE ISLANDS. THE 5-DAY RAINFALL TOTAL IS
FORECAST TO BE AROUND 2.5 INCHES FOR THE SOUTHERN SECTIONS OF
PR...AND 0.5 TO 1.25 INCHES ACROSS VIEQUES..CULEBRA...AND THE USVI.
ALAMO...WPC (USA)
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