038
FXCA20 KWBC 181228
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
828 AM EDT MON MAR 18 2024
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI MAR 18/12UTC:
ISOLATED TO LOCALLY SCATTERED SHOWERS...RESULTING IN MODEST RAIN
ACCUMULATIONS ARE FORECAST THROUGH MOST OF THE WORKWEEK.
HOWEVER...THE LATEST GUIDANCE SUGGESTS THAT FRIDAY COULD HAVE
SCATTERED TO LOCALLY NUMEROUS SHOWERS...WITH AFTERNOON CONVECTION
ACROSS WESTERN PR THAT COULD RESULT IN ISOLATED AREAS OF RAIN OF
OVER A HALF AN INCH. A SURFACE HIGH PRESSURE OVER THE CENTRAL
ATLANTIC WILL MOVE EAST NORTHEAST...REACHING THE NORTHEAST
ATLANTIC BY MIDWEEK. A SURFACE LOW AND ASSOCIATED TROUGH WILL MOVE
INTO THE WESTERN ATLANTIC TODAY...WHICH COULD WEAKEN THE LOCAL
WINDS BY THE MIDDLE OF NEXT WEEK AND FORM A COL NORTH OF PR/USVI
FROM TUESDAY INTO WEDNESDAY. BY THURSDAY...THE LOCAL WINDS WILL BE
LIGHT TO MODERATE FROM THE NORTHEAST...GRADUALLY BECOMING EASTERLY
ON FRIDAY INTO SATURDAY. THE CHANGE IN WIND DIRECTION DURING THE
LATTER PART OF THE WEEK WILL PLAY A ROLE ON THE LOCATION OF THE
AFTERNOON CONVECTION FORECAST OVER PORTIONS OF WESTERN PR. THE MID
LEVELS WILL HAVE A HIGH PRESSURE RIDGE OVER THE AREA THROUGH THE
WEEK...THOUGH A WEAK MID-LEVEL TROUGH COULD MOVE IN LATE FRIDAY
INTO SATURDAY. THIS WEAK MID-LEVEL TROUGH COULD PLAY A ROLE IN THE
OVERALL INSTABILITY THAT MAY CAUSE HIGHER AMOUNTS OF RAINFALL IN
THE AFTERNOON ACROSS WESTERN PR. THE UPPER LEVELS WILL PREVAIL
WITH A WEAK RIDGE OR ZONAL WESTERLY FLOW THROUGH THE WEEK.
THE AVAILABLE MOISTURE WILL BE NEAR TO BELOW NORMAL TODAY AND
TUESDAY. MOISTURE IS FORECAST TO INCREASE BY MIDWEEK AND REMAIN
SLIGHTLY ABOVE NORMAL STARTING ON WEDNESDAY AFTERNOON AND THROUGH
THE LATTER PART OF THE WEEK. THIS IS POSSIBLY DUE TO THE
COMBINATION OF A SFC LOW PRESSURE MOVING INTO THE CENTRAL
ATLANTIC....WITH A SFC HIGH PRESSURE MOVING INTO THE WESTERN
ATLANTIC AND THE SFC HIGH ACROSS THE NORTHEASTERN ATLANTIC. THIS
WILL CAUSE AN AREA OF CONVERGENCE ACROSS THE NORTHEAST CARIBBEAN
AND TROPICAL ATLANTIC...ENHANCING MOISTURE OVER THE AREA. THIS
MOISTURE WILL THEN COMBINE WITH THE LOCAL EFFECTS IN PR TO CAUSE
THE AFTERNOON CONVECTION EXPECTED.
THE 5-DAY RAINFALL ACCUMULATION IS FORECAST TO BE NEAR 0.50 TO 1.0
INCHES ACROSS NORTHEAST PR...AS WELL AS PORTIONS OF WESTERN TO
NORTHWESTERN PR...THOUGH ISOLATED HIGHER AMOUNTS ARE POSSIBLE.
CONFIDENCE IS STILL A BIT LOW ON THOSE AMOUNTS AS MOST OF THE
SIGNIFICANT RAIN IS EXPECTED ON FRIDAY...WHICH IS LATE INTO THE
FORECAST PERIOD. NEAR 0.25 TO 0.50 INCHES ACROSS THE CENTRAL
INTERIOR OF PR...WHILE SOME AREAS OF SOUTH CENTRAL PR ARE FORECAST
0.10 TO 0.25 INCHES. VIEQUES...CULEBRA...AND THE USVI ARE FORECAST
0.10 TO 0.25 INCHES AS WELL.
ALAMO...WPC (USA)
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