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FXCA20 KWBC 051249
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
749 AM EST TUE MAR 05 2024
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI MAR 05/12UTC:
A LARGE SFC HIGH PRESSURE SYSTEM WILL PREVAIL OVER THE NORTH
CENTRAL ATLANTIC THROUGH THE REST OF THE WORKWEEK. THERE IS A SFC
TROUGH ACROSS THE CENTRAL ATLANTIC THAT WILL SLOWLY MOVE WEST AND
COULD BE JUST NORTHEAST OF PR/USVI BY WEDNESDAY AFTERNOON. THE
LOCAL WINDS WILL BE FROM THE EAST TO ENE TODAY...SHIFTING TO THE
ESE BY WEDNESDAY AFTERNOON AND CONTINUING FROM THE ESE FOR THE
REST OF THE WORKWEEK...BEFORE RETURNING TO MORE EAST TO ENE LATE
FRIDAY INTO SATURDAY. THE AVAILABLE MOISTURE WILL BE BELOW NORMAL
TODAY...GRADUALLY INCREASING INTO THE NORMAL LEVELS ON WEDNESDAY
AND ABOVE NORMAL BY THURSDAY AFTERNOON AND FRIDAY. A BROAD MID
LEVEL TROUGH WILL START DEVELOPING LATER TODAY OVER THE LOCAL
ISLANDS...PREVAILING OVER THE NORTHEAST CARIBBEAN THROUGH THE END
OF THE WORKWEEK. THE UPPER-LEVEL WINDS WILL BE STRONGER TO THE
EAST AND NORTHWEST OF PR/USVI TODAY...BUT THE UPPER-LEVEL WINDS
WILL THEN INCREASE OVER THE LOCAL ISLANDS ON WEDNESDAY...REACHING
SPEEDS NEAR 80KT AS THE UPPER-LEVEL JET MOVES OVER THE AREA. IN
ADDITION...AN UPPER TROUGH WILL BE DEVELOPING...WITH THE TROUGH
AXIS OVER HISPANIOLA EARLY THURSDAY AND OVER PR/USVI BY THURSDAY
EVENING. THE MID TO UPPER-LEVEL TROUGHS AND WINDS WILL FAVOR AN
INCREASE IN INSTABILITY FOR THE LATTER PART OF THE WORKWEEK. THE
MOST FAVORABLE ENVIRONMENT FOR THUNDERSTORMS COULD BE LATE
THURSDAY...THOUGH THE GLOBAL MODEL RAINFALL SOLUTIONS DO NOT
SUGGEST VERY SIGNIFICANT AMOUNTS OF RAIN. LOCALLY INDUCED
CONVECTION IN THE AFTERNOONS IS POSSIBLE EACH DAY IN AREAS OF SEA
BREEZE CONVERGENCE OVER PR...THOUGH THE CHANCES OF THUNDERSTORMS
OVER PR WOULD BE HIGHER FROM WEDNESDAY INTO FRIDAY.
NOT MUCH CHANGE HAS BEEN OBSERVED IN THE OVERALL FORECAST FOR THIS
WEEK. THE GENERAL WIND FLOW AND SYNOPTIC PATTERN WOULD FAVOR TRADE
WIND ISOLATED TO SCATTERED SHOWERS AFFECTING NORTH AND EASTERN PR
AS WELL AS THE USVI...WITH THEN THE AFTERNOON CONVECTION GENERALLY
ACROSS DIFFERENT SECTIONS OF WESTERN PR. THE MODEL GUIDANCE IS IN
SOME DISAGREEMENT IN TERMS OF THE LOCATION OF THE AFTERNOON
CONVECTION...ESPECIALLY TODAY AND WEDNESDAY. THE MAIN REASON COULD
BE THAT THE CONVECTION IS EXPECTED TO BE RELATIVELY SHALLOW...WITH
THE TWIN ALGORITHM SUGGESTING A WEAK INVERSION...WHILE THE
LOW-LEVEL STEERING WINDS ARE FORECAST TO BE LIGHT AND SOMEWHAT
VARIABLE OVER WESTERN PR THIS AFTERNOON AND WEDNESDAY AFTERNOON. A
BIT MORE AGREEMENT IS PRESENTED ON THURSDAY...BUT THE GLOBAL
MODELS SEEM TO BE VERY SHY IN THE RAINFALL AMOUNTS CONSIDERING THE
ABOVE NORMAL MOISTURE AND UPPER TROUGH EXPECTED TO BE PRESENT OVER
PR/USVI BY THURSDAY AFTERNOON. OUR FORECAST REFLECTS HIGHER
RAINFALL AMOUNTS THAN THE MODEL GUIDANCE IS SUGGESTING FOR
THURSDAY AFTERNOON.
THE 5-DAY TOTAL RAINFALL FORECAST SUGGESTS NEAR 0.50 TO 0.75
INCHES ACROSS THE NORTHEASTERN QUADRANT OF PR. BETWEEN 0.25 AND
0.50 INCHES ARE FORECAST ELSEWHERE ACROSS THE SOUTHERN HALF OF PR
AS WELL AS VIEQUES...CULEBRA...AND THE USVI. THE LOCATION WITH
HIGHEST RAINFALL IS FORECAST TO BE ACROSS THE NORTHWESTERN
QUADRANT OF PR...WITH AROUND 2 TO 2.5 INCHES OF RAIN IN THE 5-DAY
FORECAST.
ALAMO...WPC (USA)
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