612
FXCA20 KWBC 141253
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
752 AM EST THU DEC 14 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI DEC 14/12UTC:
A MID-LEVEL RIDGE CENTERS NEAR 24N 61W ON THURSDAY MORNING...AND
EXTENDS INTO THE NORTHEAST CARIBBEAN. THIS IS ENHANCING THE TRADE
WIND CAP...WHICH SITS NEAR 800 HPA ACCORDING TO THE 00 UTC SAN
JUAN SOUNDING. THE TRADES ARE FROM THE NORTHEAST AND ACCELERATED
TO SPEEDS OF 20-30 KT ABOVE 925 HPA. THIS IS FAVORING ISOLATED
LIGHT TRADE WIND SHOWERS IN PORTIONS OF THE VI AND NORTHERN PUERTO
RICO.
WINDS ARE FORECAST TO REMAIN FROM THE EAST-NORTHEAST THROUGH
SATURDAY...TO THEN BECOME EASTERLIES. MOISTURE IS EXPECTED TO
REMAIN BELOW AVERAGE ON FRIDAY...BUT IS FORECAST TO INCREASE ON
SATURDAY AS A MOIST PLUME MOVES IN FROM THE NORTHEAST. THE MOIST
PLUME PERSIST THROUGH THE WEEKEND...FAVORING ABOVE NORMAL VALUES
OF AVAILABLE MOISTURE AND LARGER RAINFALL AMOUNTS. THIS COINCIDES
WITH A WEAKENING OF THE TRADE WIND CAP ASSOCIATED WITH A WEAKENING
OF THE MID-LEVEL RIDGE...WHICH WILL FAVOR DEEPER TRADE WIND
CONVECTION AND HIGHER RAINFALL RATES. MODELS ARE STRUGGLING
RESOLVING TIMING OF THE ARRIVAL OF THE MOIST PLUME AND ITS
STRUCTURE...WHICH RESULTS IN IMPORTANT QPF DISCREPANCIES. WE ARE
LEANING TOWARDS A WETTER SOLUTION ON SATURDAY...AND WET CONDITIONS
PERSISTING INTO SUNDAY. EXPECT ACCUMULATION OF 0.5-0.75 INCHES IN
THE NORTHEAST HALF OF PUERTO RICO ON SATURDAY...WHILE ON
SUNDAYEXPECT AMOUNTS OF 0.5 TO 1 INCH IN THE EASTERN THIRD OF
PUERTO RICO.
THE TRADES ARE EXPECTED TO BECOME EASTERLIES ON SUNDAY AND PERSIST
THROUGH TUESDAY. AS AVAILABLE MOISTURE REMAINS ABOVE AVERAGE
THROUGH MONDAY...EXPECT SCATTERED TRADE WIND SHOWERS TO CONTINUE
ACROSS THE ENTIRE ISLAND...FAVORING MAXIMA OF 0.2-0.4 INCHES IN
WASTERN PUERTO RICO AND THE WESTERN VI...AND MAXIMA OF 0.1-0.2
INCHES ELSEWHERE. DRIER CONDITIONS DEVELOP ON TUESDAY GIVEN THE
ADVECTION OF A MUCH DRIER AIR MASS...CHARACTERIZED BY PRECIPITABLE
WATER VALIES BELOW 30MM.
GALVEZ...WPC (USA)
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