893
FXCA20 KWBC 131245
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
845 AM EDT WED SEP 13 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI SEP 13/12UTC:
HURRICANE LEE...WELL NORTH OF THE LOCAL ISLANDS...WILL HAVE AN
INFLUENCE IN THE LOCAL WINDS FOR THE NEXT FEW DAYS. THE LOCAL
WINDS WILL BE SOUTHERLY TODAY AND THURSDAY...THEN SOUTHEAST BY
FRIDAY...EASTERLY ON SATURDAY AND POSSIBLY HAVING A NORTHEAST
COMPONENT ON SUNDAY. THE LATEST GUIDANCE SUGGESTS NEAR NORMAL
MOISTURE TODAY AND THURSDAY...THEN SLIGHTLY BELOW NORMAL ON FRIDAY
THEN INCREASING TO NEAR NORMAL FOR THE WEEKEND. PRECIPITABLE WATER
VALUES ARE FORECAST TO RANGE FROM 1.6 INCHES WHICH IS SLIGHTLY
BELOW NORMAL...TO AROUND 1.9 INCHES WHICH IS NEAR NORMAL. THE
GLOBAL MODELS ARE SUGGESTING MODEST AMOUNTS OF RAIN EACH DAY OVER
THE LOCAL ISLANDS...BUT THE HIGHER RESOLUTION MODELS ARE A BIT
MORE AGGRESSIVE AND HAVE HIGHER AMOUNTS. THEREFORE OUR FORECAST
REFLECTS TOTALS THAT ARE A BIT HIGHER THAN WHAT THE GLOBAL MODELS
ARE SUGGESTING. ALTHOUGH AT THIS TIME...MAX RAINFALL TOTALS ARE
FORECAST TO BE GENERALLY UNDER AN INCH...BUT ISOLATED HIGHER
AMOUNTS ARE POSSIBLE.
THE LATEST MODEL GUIDANCE...INDICATE THAT THE HIGHEST RAINFALL
TOTALS TODAY WILL OCCUR ACROSS THE SOUTH TO SOUTHWEST PORTIONS OF
PR...WHICH COULD REACH AROUND AN INCH OF RAIN. THERE IS ALSO A
LOCAL MAX OF RAIN ACROSS NORTHEASTERN PR WITH AROUND A THIRD OF AN
INCH IN THE FORECAST...WHILE OTHER AREAS ARE EXPECTED TO OBSERVE
UNDER A QUARTER OF AN INCH OF RAIN. THE SOUTHERLY ONSHORE FLOW MAY
CAUSE CLOUDINESS AND SHOWER ACTIVITY TO DEVELOP ACROSS THE
SOUTHERN PORTIONS OF THE ISLAND...THOUGH IT MAY BE SHALLOW ENOUGH
FOR SHOWERS TO NOT DEVELOP IN LARGE AMOUNTS ACROSS THE NORTH
CENTRAL PORTIONS OF PR...WHILE ISOLATED SHOWER ACTIVITY WOULD BE
EXPECTED ACROSS THE USVI TODAY. IT IS A SIMILAR PATTERN TO WHAT
WAS OBSERVED YESTERDAY...WHERE THERE WAS A WEAK INVERSION LIMITING
THE VERTICAL DEVELOPMENT AND MOISTURE MIXING FROM HAPPENING ON THE
NORTHERN PORTIONS OF PR...WHICH MAINTAINED THE MOISTURE IN THE
LOWER LEVELS...CAUSING THE RAINFALL DEVELOPMENT TO STRUGGLE AND
KEPT IT FROM DEVELOPING SIGNIFICANT AMOUNTS OF RAIN ACROSS THE
NORTHERN SIDE OF THE CORDILLERA CENTRAL. FOR THURSDAY...A SOMEWHAT
SIMILAR PATTERN WOULD BE EXPECTED...WITH SOME RAIN EXPECTED ACROSS
SOUTHERN PR...BUT THE MODEL GUIDANCE DOES SHOW SOME MODEST AMOUNTS
OF RAIN ACROSS PORTIONS OF NORTHERN PR IN THE
AFTERNOON...ESPECIALLY NORTHWESTERN PR...BUT THE USVI WOULD REMAIN
MOSTLY WITH ISOLATED AND BRIEF SHOWERS IN THE FORECAST. AS THE
LOCAL WINDS START TO SHIFT TO A SOUTHEASTERLY AND THEN EASTERLY
DIRECTION ON FRIDAY AND THIS WEEKEND...THE AFTERNOON CONVECTION
ACROSS WESTERN AND NORTHWESTERN PR IS EXPECTED TO DEVELOP ACROSS
WESTERN AND NORTHWESTERN PR. THE USVI HOWEVER WILL REMAIN WITH
ISOLATED TO SCATTERED SHOWERS IN THE FORECAST FOR THE 5-DAY PERIOD.
THE 5-DAY RAINFALL TOTAL IS EXPECTED TO BE AROUND 2.5 INCHES
ACROSS NORTHWESTERN PR...WHILE THE USVI AND NORTHEASTERN PR IS
FORECAST BETWEEN 0.50 AND 1 INCH.
ALAMO...WPC (USA)
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