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FXCA20 KWBC 091232
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
732 AM EST MON JAN 09 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN
09/12UTC: EMBEDDED IN A LONG-FETCH NORTHWESTERLY UPPER FLOW...A
SHORT WAVE TROUGH EXTENDS NEAR HISPANIOLA WHERE IT IS ENHANCING
CONVECTION. SATELLITE IMAGERY SHOWS SCATTERED THUNDERSTORMS OVER
SAMANA AND AREAS TO THE NORTH. DRIER CONDITIONS EXTEND OVER PUERTO
RICO. ALTOUGH THE SAN JUAN SOUNDING DOES NOT SHOW ANY SIGNIFICANT
CAP...SATELLITE IMAGERY SHOWS MOSTLY CLEAR SKIES WITH THE
EXCEPTION OF A FEW TRADE WIND SHOWERS MOVING FROM THE EAST ACROSS
THE VI AND PORTIONS OF EASTERN PUERTO RICO. ALSO OF RELEVANCE TO
THE FORECAST...A MOIST PLUME CONTINUES TO LINGER TO THE NORTH OF
THE ISLANDS GIVEN THE PERSISTENT ABSENCE OF THE SEASONAL MID-LEVEL
RIDGE. THIS MOIST PLUME WILL CONTINUE TO FAVOR WETTER-THAN-NORMAL
CONDITIONS IN THE ISLANDS DURING THE NEXT FEW DAYS.
ON THE EVOLUTION...MODELS SHOW AN UPPER RIDGE CURRENTLY ON THE
SOUTHWEST CARIBBEAN EXPANDING INTO THE REGION ON TUESDAY AND
WEDNESDAY...TO THEN YIELD TO ZONAL WESTERLY FLOW. IN THE
MID-LEVELS...A TROUGH IS EXPECTED TO DEEPEN INTO THE ISLANDS ON
MONDAY...BUT AFTERWARDS.,..EXPECT A GRADUAL TRANSITION TO
WESTERLIES AS WELL...WHICH WILL FAVOR A DECREASE IN ACCUMULATIONS
INTO THE LATE WEEK. THE TRADES WILL PLAY AN IMPORTANT ROLE ON THE
ORGANIZATION OF CONVECTION. DOMINANT SOUTHEASTERLY WIND DIRECTIONS
ON MONDAY WILL FAVOR THE ORGANIZATION OF AFTERNOON CONVECTION IN
NORTHWEST PUERTO RICO ON MONDAY...WHERE EXPECT MAXIMA OF 0.5-0.75
INCHES. ON TUESDAY AND WEDNESDAY...THE RELAXATION OF THE TRADES
WILL ALLOW DIURNAL BREEZES TO PLAY A ROLE ON THE DEVELOPMENT OF
DIURNAL CONVECTION. THIS WILL FAVOR THE LARGEST ACCUMULATIONS IN
NORTH-CENTRAL PUERTO RICO...WHERE EXPECT MAXIMA 0.75 TO 1 INCH ON
TUESDAY. THE INCREASE OF MID-LEVEL WESTERLIES IN A GENERALLY
ANTICYCLONIC PATTERN WILL FAVOR A DECREASE TO MAXIMA OF 0.25-0.5
IN NORTH-CENTRAL PUERTO RICO ON WEDNESDAY. ON THURSDAY...A WEAK
SHEAR LINE TO THE NORTH OF THE ISLANDS AND THE ASSOCIATED
NORTHEASTERLY TRADES WILL FAVOR THE LARGEST ACCUMULATIONS IN
NORTHEAST PUERTO RICO...WHERE EXPECT MAXIMA OF 0.2-0.3 INCHES.
AFTERNOON CONVECTION IN THE SOUTHWEST CORDILLERA WILL FAVOR MAXIMA
UNDER 0.4 INCHES. ON FRIDAY...A STRONG POLAR TROUGH MOVES OFF THE
EAST COAST OF THE USA. THIS WILL LOWER SURFACE PRESSURES TO THE
NORTH OF THE ISLANDS...FAVORING THE DEVELOPMENT OF SOUTHEASTERLY
TRADES. UNDER THESE CONDITIONS...EXPECT AFTERNOON CONVECTION TO
CLUSTER IN NORTHWEST PUERTO RICO AND FAVOR MAXIMA OF 0.3-0.4
INCHES.
GALVEZ/ACOSTA...WPC (USA)
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