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FXCA20 KWBC 241238
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
737 AM EST WED JAN 24 2024
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI JAN 24/12UTC:
THE PREVAILING E-ENE WIND FLOW COMBINED WITH THE AVAILABLE
MOISTURE...WILL FAVOR DAILY SHOWER ACTIVITY MAINLY AFFECTING
EASTERN PR AND THE USVI. TODAY IS EXPECTED TO BE THE DAY WITH
HIGHEST RAINFALL ACCUMULATION OVER THE 5-DAY FORECAST PERIOD AS A
STATIONARY FRONT OVER THE AREA WILL INCREASE THE AVAILABLE
MOISTURE OVER THE ISLANDS TO ABOVE NORMAL LEVELS...WITH
PRECIPITABLE WATER VALUES NEAR 1.6 INCHES. THEREFORE NORTHERN TO
EASTERN PR IS FORECAST TO OBSERVE BETWEEN 0.75 TO NEAR AN INCH OF
TOTAL RAIN FROM TODAY INTO VERY EARLY THURSDAY MORNING...WHILE THE
USVI IS FORECAST TO OBSERVE BETWEEN 0.25 AND 0.50 INCHES. EVERY
OTHER DAY FROM THURSDAY THROUGH THE WEEKEND IS FORECAST TO OBSERVE
A SIMILAR RAINFALL PATTERN...BUT WITH LOWER RAINFALL
ACCUMULATIONS. FROM TOMORROW ONWARD...THE DAILY MAX RAINFALL IS
FORECAST TO BE NEAR 0.25 INCHES OR LESS...EXCEPT FRIDAY DUE TO A
BRIEF INCREASE IN MOISTURE THAT COULD CAUSE OVER 0.50 INCHES OF
RAIN ACROSS THE LUQUILLO MOUNTAIN RANGE.
THE WIND DIRECTION AND SPEED WILL BE A RESULT OF A SFC HIGH
PRESSURE ACROSS THE WESTERN ATLANTIC. THE SFC HIGH PRESSURE WILL
REMAIN ACROSS THE WEST TO CENTRAL ATLANTIC FOR THE NEXT 5
DAYS...BEFORE A SFC LOW STARTS TO MOVE INTO THE WESTERN
ATLANTIC...CAUSING A WEAKENING OF THE PRESSURE GRADIENT AND
SHIFTING WINDS TO A SOUTHEASTERLY DIRECTION ON MONDAY...WHICH IS
LATE IN THE FORECAST PERIOD. THE MID AND UPPER LEVELS WILL
CONTINUE TO BE STABLE AS THEY ARE DOMINATED BY A RIDGE OF HIGH
PRESSURE FOR THE NEXT SEVERAL DAYS. THEREFORE NO THUNDERSTORM
DEVELOPMENT IS EXPECTED. HOWEVER...ONE THING TO NOTE IS THAT A MID
LEVEL TROUGH COULD BE MOVING IN TOWARDS THE END OF THE FORECAST
PERIOD. THE GFS MODEL IS STARTING TO SUGGEST A MID-LEVEL TROUGH
OVER HISPANIOLA INTO THE BAHAMAS ON MONDAY...CAUSING AN INCREASE
IN MID-LEVEL VORTICITY OVER PR/USVI. THAT SAID...THE MODEL
GUIDANCE FLATTENS THE TROUGH BEFORE THE AXIS GETS TOO CLOSE TO THE
LOCAL ISLANDS...SO ANY INSTABILITY ENHANCEMENT COULD BE SHORT
LIVED. BEING THAT THIS IS TOWARDS THE VERY END OF THE FORECAST
PERIOD...CONFIDENCE IS LOW.
THE 5-DAY TOTAL RAINFALL IS FORECAST TO BE NEAR 2.0 TO 2.50 INCHES
FOR EASTERN PR...1.0 TO 1.50 INCHES ACROSS VIEQUES AND
CULEBRA...WHILE WESTERN PR IS EXPECTED TO OBSERVE BETWEEN 0.10 AND
0.50 INCHES. THE USVI ARE FORECAST BETWEEN 0.50 AND 1.0 INCHES FOR
THE 5-DAY TOTAL.
ALAMO...WPC (USA)
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