927
FXCA20 KWBC 241139
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
738 AM EDT MON APR 24 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APR
24/12UTC: A MID-UPPER TROUGH EXTENDS ALONG 25N 60W...EASTERN
PUERTO RICO...INTO THE CENTRAL CARIBBEAN NEAR 15N 73W. THIS IS
INTERACTING WITH A MOIST PLUME OF TOTAL PRECIPITABLE WATER VALUES
OF 40-45MM...THAT EXTENDS FROM THE CENTRAL CARIBBEAN INTO THE
LEEWARD ISLANDS. TO THE NORTH OF THIS PLUME...WEAK LOW-LEVEL
NORTHERLY FLOW IS ADVECTING A DRIER AIR MASS FROM THE NORTH
ATLANTIC INTO PUERTO RICO...LEADING TO LOWER VALUES OF
PRECIPITABLE WATER...WHICH RANGE FROM 30-35MM OVER PUERTO RICO AND
THE NORTHWESTERN VI. THIS IS LEADING TO GENERALIZED FAIR WEATHER
CONDITIONS...WHILE VERY ISOLATED CONVECTION IS OCCURRING NEAR ST.
CROIX...AS EVIDENCED BY SATELLITE IMAGERY. FURTHERMORE...THE WET
PHASE OF THE MADDEN-JULIAN OSCILLATION AND A TROPOSPHERIC KELVIN
WAVE ARE EXITING THE REGION AS THEY PROPAGATE ACROSS THE TROPICAL
ATLANTIC ON MONDAY. AS THESE EXIT...LARGE SCALE CONDITIONS ARE
EXPECTED TO CONTINUE BECOMING MORE HOSTILE FOR ASCENT AND RAINFALL
AS THE WEEK PROGRESSES.
REGARDING THE EVOLUTION...A BROAD BUT WEAK MID-LEVEL TROUGH
PATTERN IS FORECAST TO PERSIST ACROSS THE NORTH ATLANTIC INTO THE
NORTHEAST CARIBBEAN THROUGH THE WORK WEEK. THIS WILL CONTINUE TO
LIMIT THE DEVELOPMENT OF A TRADE WIND CAP...ALLOWING FOR VERTICAL
DEVELOPMENT OF AFTERNOON CONVECTION ON A DAILY BASES.
HOWEVER...THE PRESENCE OF DRY AIR IN THE MID-TROPOSPHERE AND
GENERALIZED LARGE SCALE SUBSIDENCE WILL LIMIT POTENTIAL RAINFALL
ACCUMULATIONS. UNDER THIS PATTERN...EXPECT DIURNAL CONVECTION TO
FORM IN THE AFTERNOONS ON A DAILY BASIS...BUT TO OCCUR IN AN
ISOLATED AND BE SHORT-LIVED.
MONDAY IS EXPECTED TO BE THE WETTEST DAY...AS THE MOIST PLUME
LINGERS JUST TO THE SOUTH OF THE ISLANDS. UNDER WEAK NORTHERLY
TRADES...EXPECT DEVELOPMENT TO CLUSTER OVER AND SOUTH OF THE
CORDILLERA...TO PRODUCE ISOLATED MAXIMA OF 1-1.5 INCHES.
PRECIPITATION WILL LIKELY EXTEND TO COASTAL AREAS OF SOUTHERN AND
SOUTHEAST PUERTO RICO INTO THE EVENING...TO FAVOR ACCUMULATION OF
0.2-0.4 INCHES. DRIER CONDITIONS ARE EXPECTED AFTERWARDS. ON
TUESDAY...EXPECT MAXIMA OF 0.25-0.5 INCHES IN INTERIOR PORTIONS OF
NORTHEAST PUERTO RICO. ON WEDNESDAY...EXPECT MAXIMA OF 0.2-0.3
INCHES IN INTERIOR PORTIONS OF NORTHERN PUERTO RICO. ON
THURSDAY...EXPECT MAXIMA OF 0.2-0.4 INCHES IN INTERIOR PORTIONS OF
NORTH-CENTRAL PUERTO RICO...DECREASING TO 0.2-0.3 INCHES ON FRIDAY.
GALVEZ/ACOSTA...WPC (USA)
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