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FXCA20 KWBC 211250
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
750 AM EST THU DEC 21 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI DEC 21/12UTC:
A WEAK COLD FRONT IS FORECAST TO SLOWLY MOVE OVER THE LOCAL
ISLANDS TODAY...THEN BECOME STATIONARY JUST TO THE SOUTHEAST OR
NEAR PR/USVI BY FRIDAY AS IT DISSIPATES. THIS WILL BE ACCOMPANIED
BY NNE WINDS TODAY AND FRIDAY..THOUGH EAST TO ENE WINDS COULD
RETURN ON SATURDAY AFTERNOON...THEN WEAK NORTHEAST WINDS WOULD
RETURN LATE ON SUNDAY...BEFORE BECOMING EASTERLY ON MONDAY. THE
AVAILABLE MOISTURE WILL BE NEAR NORMAL TODAY AND FRIDAY...THEN IT
IS EXPECTED TO INCREASE TO SLIGHTLY ABOVE NORMAL BY SATURDAY
AFTERNOON...PERSISTING INTO MONDAY. IN TERMS OF PRECIPITABLE
WATER...THIS MEANS BETWEEN 1.4 AND 1.6 INCHES TODAY THROUGH
SATURDAY...THEN BETWEEN 1.6 AND 1.8 INCHES FROM LATE SATURDAY INTO
MONDAY.
IN THE WESTERN ATLANTIC THERE IS A SFC HIGH PRESSURE THAT WILL
CONTINUE TO MOVE EAST OVER THE NEXT SEVERAL DAYS...CONTRIBUTING TO
THE FRONT MOVING SOUTH AND OVER THE LOCAL ISLANDS. A BROAD MID
LEVEL TROUGH OVER THE WESTERN TROPICAL ATLANTIC IS MOVING EAST AND
A MID LEVEL LOW WILL DEVELOP OVER THE CENTRAL ATLANTIC BY THE
MIDDLE OF NEXT WEEK...MEANWHILE A MID LEVEL RIDGE WILL SLOWLY MOVE
INTO THE CARIBBEAN...THOUGH PR/USVI WILL OBSERVE WESTERLY WINDS IN
THE MID LEVELS INTO EARLY NEXT WEEK. THERE IS ALSO AN UPPER TROUGH
THAT HAS ITS AXIS OVER CUBA AND IS MOVING EAST. THE UPPER TROUGH
AXIS IS FORECAST TO BE OVER HISPANIOLA LATE FRIDAY INTO SATURDAY.
ZONAL WESTERLY WINDS ARE EXPECTED OVER THE LOCAL ISLANDS BY
SUNDAY.
THIS GENERAL PATTERN WILL FAVOR RAINFALL ACROSS THE NORTH SECTIONS
OF PR AND ACROSS THE USVI. THAT SAID...THE LIGHTER WINDS EXPECTED
COULD ALLOW SOME SEA BREEZE CONVERGENCE THIS AFTERNOON ACROSS THE
SOUTH TO SOUTHWESTERN SECTIONS OF PR...WHICH COULD PROMOTE SOME
CONVECTION. IN ADDITION...SOME RAIN SHOWERS COULD ALSO DEVELOP
ACROSS THE NORTH CENTRAL TO NORTHWEST PUERTO RICO ON FRIDAY...THEN
CENTRAL TO NORTH CENTRAL PORTIONS OF PR COULD OBSERVE SOME SHALLOW
CONVECTION THIS WEEKEND. THE USVI ARE FORECAST TO OBSERVE
ISOLATED/SCATTERED SHOWER ACTIVITY THROUGH THE FORECAST PERIOD.
THE 5-DAY TOTAL RAINFALL FORECAST SUGGESTS THAT NORTHERN PR COULD
OBSERVE BETWEEN 1 AND 2 INCHES OF RAIN...WHILE SOUTHWESTERN PR IS
FORECAST NEAR 1 INCH...A GOOD PORTION OF IT EXPECTED THIS
AFTERNOON. THE USVI ARE FORECAST BETWEEN 0.50 AND 1 INCH OF RAIN
OVER THE 5-DAY TOTAL.
ALAMO...WPC (USA)
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