956  
FXCA20 KWBC 261213  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
713 AM EST TUE JAN 26 2021  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN  
26/12UTC: ON TUESDAY MORNING...A SURFACE FRONT EXTENDS ALONG 18.5N  
OR JUST TO THE NORTH OF PUERTO RICO AND THE VI. SATELLITE IMAGERY  
SHOWS ENHANCED TRADE WIND SHOWERS ALONG THE SURFACE  
FRONT...DORRING THE NORTHERN VIRGIN ISLANDS AND ENTERING THE  
NORTHEAST COAST OF PUERTO RICO. SATELLITE DATA ALSO CONFIRMS THE  
PRESENCE OF A CAP/INVERSION...WHICH REFLECTS IN THE HORIZONTAL  
SPREAD OF FRONTAL CONVECTION. THIS IS CONSISTENT WITH THE  
STABILIZING INFLUENCE OF A LARGE MID-LEVEL RIDGE THAT CENTERS OVER  
CENTRAL CUBA/CENTRAL BAHAMAS BUT EXTENDS AN AXIS INTO THE LESSER  
ANTILLES. THE INFLUENCE OF THE RIDGE WILL LIMIT ACCUMULATIONS WITH  
THE SURFACE FRONT...FORECAST TO PEAK DURING TUESDAY MORNING.  
 
THE FRONT IS FORECAST TO DRIFT SOUTHWARD AND CROSS THE ISLANDS  
DURING TUESDAY MORNING...TO POSITION TO THE SOUTH OF PUERTO RICO  
AND THE VI BY TUESDAY EVENING. FRONTAL CONVECTION IS FORECAST TO  
PEAK DURING THE DAY ON TUESDAY...EMBEDDED IN 15-20KT EASTERLY  
TRADES. THIS WILL SUSTAIN THE LARGEST ACCUMULATIONS IN THE VIRGIN  
ISLANDS AND ESPECIALLY IN EASTERN PUERTO RICO AND THE  
CORDILLERA...WHERE EXPECTING ACCUMULATION OF 0.25-0.5 INCHES.  
SCATTERED CONVECTION AND VERY LIGHT ACCUMULATIONS ARE EXPECTED IN  
MOST OF PUERTO RICO INTO THE AFTERNOON...WITH THE EXCEPTION OF THE  
SOUTHWEST CORDILLERA WHERE ISOLATED MAXIMA NEARING 0.75 INCHES IS  
EXPECTED. ON TUESDAY EVENING...LINGERING POST FRONTAL CONVECTION  
IS FORECAST TO PEAK IN NORTHEAST PUERTO RICO TO FAVOR MAXIMA OF  
0.1-0.2 INCHES. MUCH DRIER CONDITIONS ARE EXPECTED ON WEDNESDAY  
AND THURSDAY IN ASSOCIATION WITH A MUCH DRIER AIR MASS LOCATED TO  
THE NORTH OF THE FRONT...AS WELL AS A LOW-LEVEL DIVERGENT PATTERN.  
 
ANOTHER FRONT APPROACHES FROM THE NORTH ON FRIDAY...WHILE A SHEAR  
LINE ORGANIZES TO THE SOUTHEAST OF THE VIRGIN ISLANDS. GIVEN THAT  
CONVECTION WILL ORGANIZE WITH THE FRONT AND SHEAR LINE...PUERTO  
RICO AND THE VI ARE FORECAST TO LIE BETWEEN THESE TWO SYSTEMS  
DURING THE DAY ON FRIDAY...WHICH WILL RESULT IN VERY LIGHT AND  
ISOLATED PRECIPITATION. A WETTER PATTERN IS EXPECTED ON SATURDAY  
AS THE NEXT FRONT APPROACHES THE ISLANDS.  
 
GALVEZ...WPC (USA)  

 
 
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