458  
FXCA20 KWBC 141204  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
803 AM EDT TUE MAR 14 2023  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAR  
14/12UTC: IN THE UPPER LEVELS...THE SUBEQUATORIAL RIDGE HAS  
STRENGTHENED OVER THE NORTHERN COAST OF SOUTH AMERICA AND THE  
ENTIRE CARIBBEAN. THIS HAS HELPED TO BUILD A MID-LEVEL RIDGE OVER  
THE SOUTHERN CARIBBEAN...CENTERING JUST TO THE NORTH OF PANAMA AND  
EXTENDING AN AXIS INTO THE LEEWARD ISLANDS. THE RESULT IS WESTERLY  
FLOW OVER PUERTO RICO ABOVE 800 HPA. THE SAN JUAN SOUNDING SHOWS  
AN ELEVATED TRADE WIND CAP SITTING NEAR 650 HPA. THIS WILL ALLOW  
FOR THE DEVELOPMENT OF AFTERNOON CONVECTION. PRECIPITABLE WATER  
VALUES REMAIN LOW...NEAR 1.2-1.3 INCHES. YET...A MOIST PLUME IS  
FORECAST TO MEANDER NORTHWARD INTO THE ISLANDS LATER TODAY...TO  
PROVIDE SUFFICIENT MOISTURE FOR THE DEVELOPMENT OF MODERATE  
PRECIPITATION IN INTERIOR PORTIONS OF NORTHWEST AND NORTH-CENTRAL  
PUERTO RICO. ALSO OF RELEVANCE...A FRONT IS PROPAGATING ACROSS THE  
NORTHWEST BAHAMAS. THIS SYSTEM IS FORECAST TO ACCELERATE ON  
WEDNESDAY...TO REACH PUERTO RICO AND THE VI LATE ON THURSDAY  
EVENING.  
 
THE TRADES ARE FORECAST TO CONTINUE WEAK AND FROM THE  
EAST-SOUTHEAST ON TUESDAY...WHICH WILL ALLOW THE DEVELOPMENT OF  
CONVECTION IN INTERIOR PORTIONS OF NORTHWEST AND NORTH-CENTRAL  
PUERTO RICO. THE ELEVATED CAP AND PRECIPITABLE WATER REACHING 1.5  
INCHES WILL ALLOW MAXIMA OF 1-1.4 INCHES. THE TRADES ARE FORECAST  
TO BECOME SOUTHERLIES ON WEDNESDAY AS THE FRONT AND ASSOCIATED  
TROUGH APPROACH FROM THE NORTH. GIVEN A DECREASE IN PRECIPITABLE  
WATER...EXPECT MAXIMA DECREASING TO 0.5-1 INCH IN INTERIOR  
PORTIONS OF NORTHWEST PUERTO RICO. ON THURSDAY...THE SURFACE FRONT  
IS FORECAST TO MOVE RAPIDLY INTO THE ISLANDS CIRCA 00 UTC OR IN  
THE EVENING. THERE ARE STILL SOME DISCREPANCIES ON MODEL SOLUTION  
OF PRECIPITATION WITH THIS SYSTEM. HOWEVER...WE LEAN TOWARDS  
HIGHER AMOUNTS GIVEN FAVORABLE DYNAMICS FOR ASCENT. ALTHOUGH THE  
RESIDENCE TIMES OF PRECIPITATING CONVECTION WILL BE LIMITED BY THE  
FAST PROGRESSION OF THE SYSTEM...EXPECT MAXIMA OF 1-1.5 INCHES IN  
MOST OF EASTERN PUERTO RICO INTO THE WESTERN VI...AND MAXIMA OF  
0.25 TO 1 INCH ALONG THE REST OF THE NORTH COAST OF PUERTO RICO  
AND THE VI. MUCH DRIER CONDITIONS DEVELOP AFTER...AS A MUCH DRIER  
POST FRONTAL AIR MASS SETS IN. ON FRIDAY...FAST 15-20KT  
NORTHEASTERLY TRADES WILL FAVOR MAXIMA GENERALLY UNDER 0.1 INCHES  
IN MOST OF NORTHEASTERN PUERTO RICO. ON SATURDAY...THE RETURN OF  
THE EASTERLIES WILL FAVOR MAXIMA OF 0.1-0.25 IN NORTHEAST PUERTO  
RICO AND ISOLATED MAXIMA UNDER 0.25 INCHES IN THE WESTERN  
CORDILLERA.  
 
ACOSTA/GALVEZ...WPC (USA)  

 
 
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