437
FXCA20 KWBC 211243
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
743 AM EST TUE NOV 21 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI NOV 21/12UTC:
A SFC LOW PRESSURE NEAR 31N/54W HAS AN ASSOCIATED COLD FRONT
EXTENDING TO ITS SW INTO THE ATLANTIC WATERS OF PR...THERE IS ALSO
A SFC TROUGH JUST WEST OF PR WHICH IS ASSOCIATED WITH ANOTHER SFC
LOW OVER THE SOUTH CENTRAL CARIBBEAN. THE SFC LOW IN THE ATLANTIC
WILL MOVE EAST AND THE COLD FRONT WILL ALSO MOVE EAST WITH IT.
THIS WILL CAUSE THE LOCAL WINDS TO REMAIN NORTHERLY TODAY THEN
GRADUALLY BECOMING EASTERLY BY THURSDAY. THE AVAILABLE MOISTURE
WILL ALSO DECREASE TODAY AND WILL REMAIN NEAR NORMAL TODAY...BUT
WILL BE BELOW NORMAL BY WEDNESDAY INTO EARLY THURSDAY...INCREASING
TO NORMAL VALUES THEREAFTER. IN TERMS OF PRECIPITABLE WATER...THE
VALUES COULD BE NEAR 1.9 INCHES THIS MORNING AS IT DECREASES...AND
COULD BOTTOM OUT ON WEDNESDAY MORNING AT AROUND 1.25 INCHES...THEN
INCREASE UP TO 1.7 INCHES BY FRIDAY AFTERNOON. THIS GENERAL
PATTERN WILL CAUSE SOME SHOWER ACTIVITY TO AFFECT NORTHERN AND
EASTERN PR AS WELL AS THE USVI THROUGH THE END OF THE WORKWEEK.
THE AMOUNTS OF RAIN MAY BE HIGHEST TODAY AS MOISTURE IS SILL NEAR
TO SLIGHTLY ABOVE NORMAL THIS MORNING...THOUGH DECREASING.
THEREFORE THE AMOUNTS OF RAIN EXPECTED TODAY COULD BE AS MUCH AS A
HALF AN INCH OVER NORTH AND EASTERN PR AS WELL AS AROUND THE USVI.
UNDER A HALF AN INCH OF RAIN IS FORECAST ON WEDNESDAY AND
THURSDAY...WITH THE LUQUILLO MOUNTAIN RANGE OBSERVING THE HIGHEST
AMOUNTS...NEAR A THIRD OF AN INCH OF RAIN.
IN THE MID AND UPPER LEVELS...HIGH PRESSURES IN THE MID AND UPPER
LEVELS OVER THE WESTERN CARIBBEAN WILL MOVE EAST AND PROMOTE
STABILITY OVER PR/USVI STARTING EARLY WEDNESDAY ONWARD. THIS MAY
CAUSE A CAP FROM THE MIDDLE TO THE REST OF THE WEEK...AND THUS
MAINLY SHALLOW AND ADVECTIVE SHOWER ACTIVITY WOULD BE EXPECTED
FROM WEDNESDAY ONWARD EVEN AS MOISTURE INCREASES SLIGHTLY ON
THURSDAY AND FRIDAY. THE OVERALL RAIN PATTERN IS EXPECTED TO BE
SIMILAR ON THE LATTER PART OF THE WEEK INTO THE
WEEKEND...AFFECTING MAINLY THE USVI AND EASTERN PR...BUT WITH
MODEST AMOUNTS OF RAIN...GENERALLY UNDER A QUARTER OF AN INCH OF
RAIN.
THE 5-DAY TOTAL RAINFALL FORECAST IS TO REACH 1.5 INCHES ACROSS
SECTIONS OF NORTHEASTERN PR. THE USVI COULD OBSERVE UP TO 0.75 -
1.25 INCHES OF RAIN OVER THE 5-DAY PERIOD...WITH ST CROIX EXPECTED
TO OBSERVE THE HIGHER AMOUNTS.
ALAMO...WPC (USA)
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