643  
FXCA20 KWBC 271248  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
848 AM EDT WED SEP 27 2023  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI SEP 27/12UTC:  
THE MAIN STORY IS THE POTENTIAL IMPACT OF TROPICAL STORM PHILIPPE  
OVER PR/USVI THIS WEEKEND INTO EARLY NEXT WEEK. THE LATEST  
FORECAST BY THE NATIONAL HURRICANE CENTER HAS PHILIPPE WEAKENING  
GRADUALLY OVER THE NEXT FEW DAYS...GETTING CLOSER TO THE LOCAL  
ISLANDS THIS WEEKEND...THOUGH THE FORECAST SUGGESTS IT WILL BE A  
REMNANT LOW OR POST TROPICAL SYSTEM BY THEN. THE NATIONAL  
HURRICANE FORECAST TRACK ON PHILIPPE IS CLOSER TO THE ECMWF MODEL  
THAN THE GFS...THEREFORE THE RAINFALL FORECAST REFLECTS MORE  
CONSIDERATION AND PREFERENCE FOR THE ECMWF MODEL. THE RAINFALL  
AMOUNTS SUGGESTED BY THE ECMWF MODEL ARE GENERALLY UNDER 2 INCHES  
FOR THE 48-HOUR PERIOD OF SUNDAY AND MONDAY...WITH THE HIGHER  
AMOUNTS AFFECTING THE USVI...VIEQUES...CULEBRA AND SOME COASTAL  
MUNICIPALITIES OF MAINLAND PR. THERE IS CONSIDERABLE UNCERTAINTY  
IN THE RAINFALL FORECAST ASSOCIATED TO PHILIPPE...AND THE LATEST  
FORECASTS BY THE NATIONAL HURRICANE CENTER SHALL BE MONITORED AND  
CONSIDERED WITH EACH ISSUANCE.  
 
FROM TODAY THROUGH SATURDAY...THE AVAILABLE MOISTURE WILL RANGE  
BETWEEN 2.1 AND 1.7 INCHES...WHICH IS IN THE NORMAL RANGE FOR THE  
DATE...BUT MOISTURE WILL INCREASE ON SUNDAY AS PHILIPPE  
APPROACHES. THE RAINFALL COVERAGE TODAY AND THURSDAY WILL BE  
FAIRLY TYPICAL...ISOLATED TO SCATTERED SHOWERS ACROSS THE USVI AND  
EASTERN PR...WHILE AFTERNOON CONVECTION IS EXPECTED ACROSS THE  
SOUTHWESTERN QUADRANT OF PR...SINCE THERE WILL BE ENE-NE WINDS  
OVER THE AREA. THE LOCAL WINDS MAY WEAKEN BY FRIDAY INTO  
SATURDAY...AND THE RAINFALL PATTERN IS EXPECTED TO FAVOR THE  
NORTHEASTERN SECTORS OF PR AS WELL AS THE NORTHERN USVI  
 
IN TERMS OF RAINFALL AMOUNTS...THE ACTIVITY EXPECTED THIS  
AFTERNOON COULD PRODUCE OVER AN INCH OF RAIN OVER SOUTHWESTERN  
PR...BUT HIGHER ISOLATED AMOUNTS ARE POSSIBLE...POSSIBLY NEAR 0.75  
INCHES ACROSS NORTHEASTERN PR AND AROUND A QUARTER OF AN INCH FOR  
THE USVI. THURSDAY WOULD BE SIMILAR...WITH A POSSIBILITY OF OVER  
AN INCH OF RAIN ACROSS CENTRAL...WESTERN...AND SOUTHWESTERN  
PR...THEN AROUND 0.25 INCHES ARE FORECAST FOR NORTHEASTERN  
PR...WHILE THE USVI ARE FORECAST TO OBSERVE AROUND A TENTH OF AN  
INCH OF RAIN. FRIDAY IS FORECAST TO HAVE AROUND 0.25 TO 0.5 INCHES  
ACROSS NORTHERN AND EASTERN PR...AS WELL AS THE NORTHERN  
USVI...BUT ST CROIX IS FORECAST TO OBSERVE UNDER 0.25 INCHES. FOR  
THE WEEKEND...BASED ON THE LATEST GUIDANCE...A SIMILAR RAINFALL  
PATTERN TO FRIDAY IS EXPECTED...BUT THE AMOUNTS ARE HIGHER WITH  
MAX VALUES OF OVER A HALF AN INCH ON SATURDAY INTO SUNDAY...AND  
NEAR AN INCH OF RAIN ON SUNDAY INTO MONDAY.  
 
THE 5-DAY RAINFALL TOTAL IS FORECAST TO BE AROUND 3 TO 3.25 INCHES  
ACROSS THE SOUTHWESTERN SECTIONS OF PR...NORTH EASTERN PR IS  
FORECAST JUST UNDER 3 INCHES...WHILE THE USVI IS FORECAST 1.25 TO  
2 INCHES.  
 
ALAMO/ACOSTA...WPC (USA)  

 
 
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