441
FXCA20 KWBC 271219
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
819 AM EDT THU APR 27 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APR
27/12UTC: THE MJO ANALYSIS SHOWS RAPIDLY INCREASING UPPER
CONVERGENT CONDITIONS ACROSS THE CARIBBEAN AND THE AMERICAS. THIS
IS CONSISTENT WITH A GENERALIZED DECREASE IN THE COVERAGE OF DEEP
CONVECTION ACROSS THE CONTINENT. OVER THE NORTHEAST
CARIBBEAN...MID-UPPER WESTERLY FLOW CONTINUES. EMBEDDED IN THIS
FLOW...WEAK SHORT WAVE PERTURBATIONS ARE PROPAGATING FROM WEST TO
EAST. ALTHOUGH THESE TROUGHS ARE FAVORING SOME
ASCENT...ENTRAINMENT OF DRY AIR PRESENT IN THE MID-TROPOSPHERE IS
FAVORING TO LITTLE CLOUDINESS THIS MORNING. PRECIPITABLE WATER
REMAINS LOW...BUT A MOIST PLUME OF VALUES RANGING 40-45MM IS
ENTERING FROM THE SOUTHEAST. THIS WILL FUEL AFTERNOON CONVECTION
ONCE AGAIN IN INTERIOR PORTIONS OF NORTHERN PUERTO
RICO...INCLUDING THE SAN JUAN METRO AREA...AS WEAK SOUTHERLY
TRADES PERSIST INTO THE EVENING.
ON THE FORECAST...THURSDAY WILL LIKELY BE THE WETTEST DAY AS THE
WEAK UPPER TROUGH INTERACTS WITH THE MOIST PLUME ARRIVING INTO
PUERTO RICO THIS MORNING. UNDER THE INFLUENCE OF WEAK SOUTHERLY
TRADES...EXPECT DIURNAL MOISTURE CONVERGENCE TO CONTINUE
CLUSTERING IN INTERIOR PORTIONS OF NORTHERN PUERTO RICO. WESTERLY
FLOW AND THE INFLUENCE OF THE MID-UPPER TROUGH WILL DRAW ACTIVITY
TO THE SAN JUAN METRO AREA IN THE LATE AFTERNOON. EXPECT MAXIMA OF
1-1.25 INCHES ALONG NORTHERN PORTIONS OF THE CORDILLERA...WHILE IN
THE SAN JUAN METRO EXPECT GENERALLY 0.25-0.75 INCHES.
MODELS THEN RESOLVE A MID-LEVEL RIDGE PATTERN STRENGTHENING OVER
THE CENTRAL CARIBBEAN. THE RIDGE IS FORECAST TO MEANDER
NORTHEASTWARD DURING THE WEEKEND...TO CENTER OVER HISPANIOLA AND
PUERTO RICO BY SUNDAY. THIS...IN COMBINATION WITH THE UNFAVORABLE
MJO...WILL LIKELY FAVOR A DRYING TREND IN THE NEXT FEW DAYS. TRADE
WINDS ARE FORECAST TO REMAIN WEAK THROUGH SATURDAY. AFTER THIS
PERIOD...A REORGANIZATION OF THE BERMUDA HIGH TO THE NORTH WILL
LEAD TO A GRADUALL ACCELERATION AND TO THE DEVELOPMENT OF A
SOUTHEASTERLY WIND COMPONENT. IN TERMS OF PRECIPITATION
AMOUNTS...DIURNAL ACTIVITY WILL CLUSTER IN INTERIOR PORTIONS OF
NORTHWEST PUERTO RICO ON A DAILY BASIS FROM FRIDAY AND ON. ON
FRIDAY...EXPECT MAXIMA OF 0.75 TO 1 INCH. THIS DECREASES TO MAXIMA
OF 0.4-0.7 INCHES BY SATURDAY AND SUNDAY. A LOCAL INCREASE IN
MOISTURE CONVERGENCE WILL FAVOR A SLIGHT INCREASE IN MAXIMUM
ACCUMULATIONS.
GALVEZ/ACOSTA...WPC (USA)
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