322
FXCA20 KWBC 101232
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
732 AM EST TUE JAN 10 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN
10/12UTC: A MID-UPPER LEVEL TROUGH EXTENDS FROM 30N 67W INTO
PUERTO RICO ON TUESDAY MORNING. THIS ASSOCIATES WITH A SURFACE
COLD FRONT THAT EXTENDS ACROSS THE SOUTH-CENTRAL BAHAMAS. A SHEAR
LINE IS ALSO PRESENT ACROSS HISPANIOLA. THE3 LOWER PRESSURES
ASSOCIATED WITH THE FRONT ARE FAVORING SOUTHEASTERLY TRADES ACROSS
PUERTO RICO AND THE VI. THIS IS STEERING SCATTERED SHALLOW
CONVECTION ACROSS THE VI AND PORTIONS OF SOUTHERN AND SOUTHEAST
PUERTO RICO.
ON TUESDAY...THE CURRENT UPPER TROUGH WILL PROVIDE DYNAMICS AND
INSTABILITY FOR LOCALIZED ENHANCED ASCENT. GIVEN THE WEAKENING ON
THE SOUTHEASTERLY TRADES AS THE DAY PROGRESSES...CONVECTION WILL
BE SENSITIVE TO THE CONVERGENCE OF DIURNAL BREEZES. THIS WILL
RESULT IN THE LARGEST ACCUMULATIONS IN THE CENTRAL CORDILLERA AND
PORTIONS OF NORTH-CENTRAL PUERTO RICO. EXPECT MAXIMA OF 0.5-0.75
INCHES ALTHOUGH VERY ISOLATED HIGHER AMOUNTS ARE POSSIBLE. THE
MID-UPPER TROUGH IS PROGRESSIVE...AND IS FORECAST TO EXIT THE AREA
EARLY ON WEDNESDAY. A BROAD TROUGH STARTS TO ENTER FROM THE
NORTHWEST ON WEDNESDAY. YET...EMBEDDED IN THE BASE OF THIS
TROUGH...A SHORT WAVE IS FORECAST TO CROSS THE ISLANDS DURING THE
DAY ON WEDNESDAY. TRADES ARE FORECAST TO REMAIN WEAK WITH AN
EASTERLY COMPONENT...TO ONCE AGAIN...FAVOR THE ROLE OF DIURNAL
BREEZES. THIS WILL FAVOR A SIMILAR DISTRIBUTION OF PRECIPITATION.
ON THURSDAY...NORTHEASTERLY TRADES RETURN. A SHEAR LINE IS
EXPECTED TO THE NORTH OF THE ISLANDS...BUT CURRENT MODEL GUIDANCE
DOES NOT SUGGEST A DIRECT IMPACT. REGARDLESS...THE GDI SHOWS
UNSEASONABLY HIGH VALUES WHICH WILL LIKELY FAVOR SCATTERED LIGHT
CONVECTION. THE LARGEST AMOUNTS ARE EXPECTED IN THE SOUTHWEST
CORDILLERA REACHING ISOLATED MAXIMA OF 0.5-0.75 INCHES.
A CHANGE OF PATTERN IS EXPECTED ON THURSDAY...AS A LARGE UPPER
TROUGH EXITS THE EASTERN SEABOARD. THIS WILL FAVOR A LOWERING OF
THE SURFACE PRESSURES IN THE BAHAMAS/WESTERN ATLANTIC...WHICH WILL
RESULT IN A SHIFT OF THE TRADES TO SOUTHEASTERLIES. THIS WILL
CLUSTER AFTERNOON CONVECTION IN NORTHWEST PORTIONS OF THE
ISLAND...FORECAST TO REACH MAXIMA OF 0.2-0.4 INCHES.
GALVEZ/ACOSTA...WPC (USA)
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