085
FXCA20 KWBC 141243
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
742 AM EST WED DEC 14 2022
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM DEC
14/12UTC: IN THE LARGE SCALE...A TROPOSPHERIC KELVIN WAVE IS
CROSSING THE CARIBBEAN BASIN...BUT ITS EFFECTS ARE MOSTLY FELT IN
NORTHERN SOUTH AMERICA AND THE LESSER ANTILLES. IN THE UPPER
LEVELS...A LARGE TROUGH EXTENDS FROM THE NORTH ATLANTIC INTO THE
NORTHEAST CARIBBEAN. ITS AXIS EXTENDS FROM 31N 58W OR EAST OF
BERMUDA INTO THE WESTERN LEEWARD ISLANDS. THIS TROUGH IS ENHANCING
PRECIPITATION IN THE WINDWARD ISLANDS AND CENTRAL LESSER
ANTILLES...WHERE A LARGE AREA OF ENHANCED OUTFLOW IS EVIDENT IN
SATELLITE IMAGERY. YET IN PUERTO RICO...THE PRESENCE OF A DRY AIR
MASS OVER 830 HPA AND A STRONG TRADE WIND CAP ARE LIMITING
CONVECTION...AS EVIDENCED BY THE SAN JUAN SOUNDING. IN THE
MEANTIME...A MID-LEVEL RIDGE CENTERS ON A HIGH OVER WESTERN CUBA.
THIS RIDGE IS FORECAST TO GRADUALLY BUILD INTO THE EASTERN
CARIBBEAN TO CONTINUE FAVORING SEASONALLY DRY CONDITIONS.
THE UPPER TROUGH IS FORECAST TO MOVE EAST ON WEDNESDAY AND
THURSDAY...WHILE ANOTHER UPPER TROUGH FORMS OVER THE REGION IN
RESPONSE TO A BUILDING UPPER RIDGE OVER THE WESTERN CARIBBEAN.
HOWEVER...PRESENCE OF DRY AIR AND THE MID-LEVEL RIDGE BUILDING
FROM THE WEST WILL BE THE DOMINANT FEATURES...TO LIMIT VERTICAL
DEVELOPMENT OF CONVECTION. ACTIVITY WILL BE MOSTLY ASSOCIATED WITH
WEAK PERTURBATIONS COMING FROM THE EAST IN THE TRADES. UNDER THE
INFLUENCE OF A TRADE WIND CAP...EXPECT THE LARGEST ACCUMULATIONS
IN EASTERN PUERTO RICO MOSTLY IN MORNING HOURS. THIS WILL FAVOR
ENHANCED SHOWERS ON THURSDAY NIGHT-FRIDAY MORNING TO FAVOR MAXIMA
NEAR 0.2 INCHES. ON FRIDAY EVENING-EARLY SATURDAY EXPECT MAXIMA
PEAKING AT 0.25-0.35 INCHES IN NORTHEAST PUERTO RICO. AFTER THIS
PERIOD...EXPECT A SLIGHT DECREASE IN ACCUMULATIONS AND LITTLE
CHANGE IN THE PATTERN.
GALVEZ/ACOSTA...WPC (USA)
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