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FXCA20 KWBC 181255
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
755 AM EST MON DEC 18 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI DEC 18/12UTC:
THERE IS A COLD FRONT ACROSS THE CENTRAL CARIBBEAN AND NORTH INTO
THE BAHAMAS THAT IS EXPECTED TO SLOWLY MOVE EAST AND THEN
SOUTH...APPROACHING THE LOCAL ISLANDS BY WEDNESDAY AS IT WEAKENS.
THERE IS ALSO A WEAKENING COLD FRONT TO THE NORTH-NORTHEAST OF
PUERTO RICO/USVI THAT WILL FRAGMENT THROUGH THE DAY. A WEAK
SURFACE LOW PRESSURE ACROSS THE CENTRAL TROPICAL ATLANTIC WILL
SLOWLY MOVE WEST OVER THE NEXT FEW DAYS...BUT IT IS EXPECTED TO BE
ABSORBED BY ANOTHER SURFACE LOW THAT WILL DEVELOP OVER THE
NORTHWESTERN ATLANTIC BY LATE THURSDAY. IN THE MID LEVELS...A
BROAD THROUGH WILL PASS TO THE NORTH OF THE LOCAL ISLANDS THROUGH
THE WEEK...CAUSING WESTERLY WINDS IN THE MID LEVELS. IN THE UPPER
LEVELS...A RIDGE WILL BE PRESENT TODAY AND TOMORROW...WHILE
STRONGER WINDS AND WESTERLY FLOW WOULD BE EXPECTED EARLY ON
WEDNESDAY ASSOCIATED WITH AN UPPER TROUGH ACROSS THE WESTERN
ATLANTIC. HOWEVER...AN UPPER TROUGH WILL MOVE INTO THE CENTRAL
CARIBBEAN BY FRIDAY AND STRONG SOUTHWESTERLY WINDS AFFECT THE
LOCAL ISLANDS IN THE UPPER LEVELS.
THIS PATTERN WOULD PROMOTE GENERALLY FAIR WEATHER WITH PERHAPS
VERY SHALLOW SHOWER ACTIVITY THROUGH MIDWEEK...AS THERE WILL BE
ALSO A TRADE WIND INVERSION THROUGH THE FIRST HALF OF THE WEEK AT
ABOUT THE 850 MB LEVEL...ERODING BY THURSDAY. IN TERMS OF
AVAILABLE MOISTURE...WE WILL REMAIN NEAR NORMAL BUT HAVING PATCHES
OF MOISTURE AND DRIER AIR FOR THE NEXT SEVERAL DAYS...THOUGH
FRIDAY IS FORECAST TO HAVE ABOVE NORMAL MOISTURE THROUGH THE DAY.
ANOTHER THING TO NOTE IS THAT THE THICKNESS AT THE LOW TO MID
LEVELS WILL DROP AS THE WEEK PROGRESSES...AND THE RELATIVE
HUMIDITY IN THE LOWER LEVELS WILL INCREASE FOR THE LATTER PART OF
THE WEEK. COMBINING THIS WITH THE INCREASING MOISTURE EXPECTED FOR
FRIDAY...WILL RESULT IN FRIDAY BEING THE DAY WITH THE MORE
WIDESPREAD COVERAGE OF RAIN AS WELL AS WITH THE HIGHEST AMOUNTS OF
RAIN IN THE FORECAST...ESPECIALLY OVER NORTHERN PUERTO RICO.
ALTHOUGH RAINFALL IS EXPECTED TO BE LIMITED OVER THE NEXT THREE
DAYS WITH RAINFALL MAXIMA AT 0.25 INCHES OR LESS TODAY THROUGH
WEDNESDAY... THURSDAY AND FRIDAY ARE FORECAST TO BE WETTER. THE
5-DAY RAINFALL TOTAL FORECAST IS SUGGESTING OVER AN INCH OF RAIN
ACROSS NORTH COASTAL PUERTO RICO AND JUST OVER 0.50 INCHES OVER
THE NORTHERN USVI...WHILE THE REST OF THE AREA COULD OBSERVE
BETWEEN 0.25 AND 0.5 INCHES OF RAIN.
ALAMO...WPC (USA)
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