636
FXCA20 KWBC 201226
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
726 AM EST TUE DEC 20 2022
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM DEC
20/12UTC: A MID-LEVEL RIDGE EXTENDS FRMO NORTHERN CENTRAL AMERICA
ACROSS THE ENTIRE NORTHERN CARIBBEAN INTO 20N 55W. THIS IS
ENHANCING THE TRADE WIND CAP...WHICH ACCORDING TO THE SAN JUAN
SOUNDING WAS ESTABLISHED AT A VERY LOW ALTITUDE OR NEAR 925 HPA.
ANOTHER CAP WAS PRESENT NEAR 700 HPA. A MOISTURE POOL THAT
RESULTED FROM THE REMNANTS OF A SHEAR LINE IS MOVING ACROSS THE
ISLANDS FROM SOUTH TO NORTH ON TUESDAY. THIS IS FAVORING SCATTERED
LIGHT CONVECTION MOVING FROM EAST NORTHEAST TO WEST-SOUTHWEST
ACROSS THE WESTERN VIA AND EASTERN PUERTO RICO. THE SAN JUAN RADAR
SHOWS VERY LIGHT RAIN SHOWERS DEVELOPING IN THESE REGIONS.
THE MID-LEVEL RIDGE IS FORECAST TO SET FOOTHOLD OVER THE NORTHERN
CARIBBEAN THROUGH THE ENTIRE FORECAST CYCLE. THIS WILL LIMIT THE
VERTICAL DEVELOPMENT OF CONVECTION AND ASSOCIATED PRECIPITATION.
TUESDAY IS EXPECTED TO BE THE WETTEST DAY DUE TO THE LARGEST
AMOUNTS OF AVAILABLE MOISTURE AS THE SHALLOW MOIST POOL MOVES
THROUGH THE ISLANDS. THIS WILL FAVOR MAXIMA OF 0.25-0.35 INCHES IN
EASTERN PUERTO RICO AND SIMILAR AMOUNTS ON THE WESTERN CORDILLEDA
IN AN ISOLATED MANNER. IN THE NORTHERN VI EXPECT SCATTERED MAXIMA
NEARING 0.2 INCHES. THE MOIST PLUME EXITS THE REGION ON WEDNESDAY
WHILE THE FLOW DEVELOPS A SLIGHT SOUTHEASTERLY COMPONENT. THIS
WILL FAVOR A DECREASE IN AMOUNTS...AND AFTERNOON CONVECTION
CLUSTERING IN EXTREME NORTHWEST PUERTO RICO TO PRODUCE MAXIMA OF
0.3-0.4 INCHES. AMOUNTS AND THE COVERAGE OF PRECIPITATING
CONVECTION DECREASE SIGNIFICANTLY ON THURSDAY AND FRIDAY. ON
SUNDAY...AN INCREASE IN THE SPEED OF THE TRADES WILL SUSTAIN AN
INCREASE LOW-LEVEL MOISTURE IN EASTERN PUERTO RICO AND THE WESTERN
VI. THIS WILL LIKELY FAVOR SLIGHTLY HIGHER ACCUMULATIONS PEAKING
IN LATE NIGHT AND EARLY MORNING HOURS. EXPECT MAXIMA INCREASING TO
0.2-0.3 INCHES.
GALVEZ/ACOSTA...WPC (USA)
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