712
FXCA20 KWBC 121228
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
828 AM EDT FRI MAY 12 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY
12/12UTC: EMBEDDED IN ZONAL WESTERLY FLOW IN THE MID AND UPPER
TROPOSPHERE...WEAK SHORT WAVE TROUGHS ARE PROPAGATING ACROSS THE
GREATER ANTILLES. ONE IS LOCATED NEAR HISPANIOLA AND A WEAKER ONE
OVER PUERTO RICO. IN THE LOWER LEVELS...THE TRADES HAVE AN
EASTERLY COMPONENT AND SPEEDS OF 10-15KT. SATELLITE IMAGERY SHOWS
GENERALIZED FAIR WEATHER CONDITIONS OVER THE ISLANDS...WITH
EXCEPTION OF A FEW POCKETS OF SHALLOW CONVECTION ACROSS THE VI AND
EASTERN PUERTO RICO. OF RELEVANCE...A MOIST PLUME IS PRESENT
ACROSS THE LEEWARD ISLANDS. SATELLITE DERIVATIONS OF PRECIPITABLE
WATER ARE CONSISTENT IN SHOWING VALUES OF 45-50MM WITH THIS MOIST
PLUME. UNDER THE INFLUENCE OF THE SHORT WAVE TROUGHS ACROSS THE
GREATER ANTILLES AND DEVELOPING SOUTHEASTERLY COMPONENT IN THE
TRADES...EXPECT THIS MOIST PLUME TO APPROACH THE ISLANDS LATE ON
FRIDAY INTO SATURDAY TO FAVOR A NOTICEABLE INCREASE IN ACTIVITY
ACROSS THE VI.
MODELS ARE STILL STRUGGLING WITH THE INITIALIZATION OF
PRECIPITABLE WATER...WHICH IS POSSIBLY THE MAIN PREDICTOR DURING
THIS PARTICULAR WEATHER PATTERN WITHOUT SIGNIFICANT SYNOPTIC
SYSTEMS IN PLACE. THE ECMWF IS CAPTURING BETTER WHAT CAN BE SEEN
IN SATELLITE OBSERVATIONS...WHICH GIVES MORE CONFIDENCE TRENDING
TOWARDS ECMWF SOLUTIONS. MOST MODELS...AND ESPECIALLY THE
ECMWF...HAVE CORRECTED NORTHWARD WITH THE MOIST PLUME PRESENT IN
THE LEEWARD ISLANDS ON FRIDAY MORNING. THIS...IN COMBINATION WITH
A SLOWER SHORT WAVE UPPER TROUGH CROSSING PUERTO RICO FROM WEST TO
EAST ON FRIDAY...WILL LIKELY FAVOR A MUCH WETTER SCENARIO FOR THE
VI ON FRIDAY NIGHT INTO SATURDAY...AND FOR PUERTO RICO ON SATURDAY.
ON FRIDAY...EXPECT AFTERNOON CONVECTION IN WESTERN PUERTO RICO TO
FAVOR MAXIMA OF 1-1.5 INCHES. EXPECT AN INCREASE IN ACTIVITY IN
THE LATE AFTERNOON INTO THE EARLY MORNING ACROSS THE VI...AS THE
MOIST PLUME ENTERS IN PHASE WITH THE APPROACHING SHORT WAVE UPPER
TROUGH FROM THE WEST. THIS WILL LIKELY FAVOR MAXIMA OF 0.5-1
INCH...ALTHOUGH ISOLATED HIGHER AMOUNTS ARE POSSIBLE IN SAINT
CROIX POTENTIALLY EXCEEDING 1.5 INCHES. REMAINING ENHANCED
MOISTURE ON SATURDAY WILL FAVOR STRONG AFTERNOON CONVECTION IN
NORTHWEST PUERTO RICO...WHERE EXPECT MAXIMA OF 2-2.5
INCHES...WHILE STREAMERS IN THE VI AND EASTERN PUERTO RICO FAVOR
MAXIMA OF 0.3-0.5 INCHES. A DRYING TREND FOLLOWS. ALTHOUGH MODELS
ARE STRUGGLING CAPTURING THE AMOUNTS OF AVAILABLE MOISTURE...WE
ARE LEANING TOWARDS THE DRIER SOLUTIONS GIVEN STILL UPPER
CONVERGENT CONDITIONS IN ASSOCIATION WITH THE MJO...AND A WEAK
MID-LEVEL RIDGE PATTERN OVER THE EASTERN CARIBBEAN. UNDER THE
INFLUENCE OF SOUTHEASTERLY TRADES...EXPECT THE HIGHER AMOUNTS TO
CONTINUE CLUSTERING IN NORTHWEST PUERTO RICO IN THE
AFTERNOONS...SHIFTING TO NORTH-CENTRAL PUERTO RICO ON TUESDAY
ASSOCIATED WITH A SLIGHT SOUTHWESTERLY WIND COMPONENT IN 700 HPA.
IN TERMS OF AMOUNTS...EXPECT ISOLATED MAXIMA OF 1-1.5 INCHES ON
SUNDAY...DECREASING TO MAXIMA OF 0.4-0.7 INCHES ON MONDAY AND
TUESDAY.
GALVEZ/ACOSTA...WPC (USA)
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