355
FXCA20 KWBC 111248
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
748 AM EST WED JAN 11 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN
11/12UTC: ON WEDNESDAY MORNING...AN UPPER TROUGH EXTENDS FROM 30N
65W INTO THE CENTRAL BAHAMAS...AND ASSOCIATES WITH A SURFACE FRONT
THAT EXTENDS ALONG 30N 53W INTO THE SOUTHEAST BAHAMAS. SCATTERED
DEEP CONVECTION IS OCCURRING WELL TO THE NORTH OF THE ISLANDS IN
ASSOCIATION WITH THESE SYSTEMS. A WEAK SHEAR LINE EXTENDS INTO
HISPANIOLA...WHICH IS ALSO RESULTINC IN SCATTERED CONVECTION.
PUERTO RICO LIES UNDER THE INFLUENCE OF A PREFRONTAL TROUGH
STRUCTURE. THIS ASSOCIATES WITH WEAK WINDS AND VERY LITTLE
CLOUDINESS THIS MORNING. UNDER THIS PATTERN...DIURNAL BREEZES WILL
PLAY AN IMPORTANT ROLE IN THE TRIGGERING OF CONVECTION IN THE
AFTERNOON...FOCUSING THE LARGEST ACCUMULATIONS IN CENTRAL PORTIONS
OF THE ISLAND.
REGARDING THE EVOLUTION...UNSEASONABLY WET CONDITIONS ARE EXPECTED
TO CONTINUE AT LEAST THROUGH THE NEXT FOUR DAYS...GIVEN AN ACTIVE
PATTERN OF PROGRESSIVE POLAR TROUGHS AND MOIST PLUMES LINGERING
NEAR AND NORTH OF THE ISLANDS. FROM THE SYSTEMS IN THE FORECAST
CYCLE...THE MOST IMPRESSIVE IS A POTENT LARGE POLAR TROUGH THAT IS
FORECAST TO EXIT THE EAST COAST OF THE USA ON SATURDAY. THIS WILL
UNDULATE A ROBUST SURFACE FRONT THAT IS FORECAST TO MAKE IT INTO
THE LEEWARD ISLANDS AND THE CENTRAL CARIBBEAN BY EARLY NEXT
WEEK...LEAVING PUERTO RICO AND THE VI WELL INSIDE THE COOL AIR
MASS. THE FRONT IS FORECAST TO ENTER PUERTO RICO ON SUNDAY
MORNING. THIS WILL LIKELY FAVOR A BURST IN PRECIPITATION EARLY ON
SUNDAY...TO FAVOR ACCUMULATION OVER 0.5 INCHES IN NORTHERN PUERTO
RICO.
IN THE MEAN TIME...THE TRADES ARE EXPECTED TO REMAIN WEAK ON
WEDNESDAY AND THURSDAY. THIS...COMBINED WITH ENHANCED AVAILABILE
MOISTURE AND INSTABILITY...AND PLENTY OF SOLAR RADIATION IN
MORNING HOURS...WILL FAVOR UNSEASONABLY STRONG AFTERNOON
CONVECTION PRIMARILY IN THE CORDILLERA. EXPECT MAXIMA OF 1-2
INCHES IN THE CENTRAL CORDILLERA ON WEDNESDAY...AND SIMILAR
AMOUNTS IN WESTERN CORDILLERA ON THURSDAY. DRIER CONDITIONS ARE
EXPECTED ON FRIDAY AND SATURDAY BEFORE THE FRONT APPROACHES LATE
ON SATURDAY NIGHT/EARLY SUNDAY MORNING.
GALVEZ/ACOSTA...WPC (USA)
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