191  
FXCA20 KWBC 261244  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
843 AM EDT TUE SEP 26 2023  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI SEP 26/12UTC:  
AVAILABLE MOISTURE WILL GRADUALLY DECREASE TODAY...REACHING BELOW  
NORMAL LEVELS BY THIS EVENING...THEN REMAINING NEAR NORMAL THROUGH  
THE REST OF THE WORKWEEK. PRECIPITABLE WATER WILL BE NEAR 1.9  
INCHES THIS MORNING...DECREASING TO AROUND 1.6 INCHES BY THE EARL  
EVENING HOURS...THEN NEAR 1.7 TO 2.0 INCHES FROM WEDNESDAY MORNING  
THROUGH FRIDAY. IN TERMS OF RAINFALL COVERAGE OVER THE AREA...A  
TYPICAL PATTERN OF AFTERNOON SHOWERS ACROSS WESTERN PR AND  
SCATTERED SHOWERS OVER EASTERN PR AND THE USVI IS EXPECTED EACH  
DAY THIS WEEK. IN THIS CASE...SINCE THERE ARE EAST NORTHEAST WINDS  
EXPECTED...THE AFTERNOON CONVECTION IN PR...WILL BE MAINLY ACROSS  
THE SOUTHWEST QUADRANT OF THE ISLAND. THE HI-RES MODEL GUIDANCE IS  
A BIT MORE AGGRESSIVE WITH THE RAINFALL TOTALS...WHICH IS TO BE  
EXPECTED CONSIDERING THAT SMALL SCALE FEATURES WILL PLAY A ROLE IN  
THE SHOWER DEVELOPMENT...SUCH AS SEA BREEZE CONVERGENCE.  
THEREFORE...FOR TODAY...THE HIGHEST AMOUNTS OF RAIN ARE FORECAST  
ACROSS SOUTHWESTERN PR...WHILE ISOLATED SHOWERS ARE FORECAST  
ACROSS THE USVI AND EASTERN PR. A SIMILAR RAINFALL PATTERN IS  
EXPECTED ON WEDNESDAY...BUT WITH SLIGHTLY MORE RAINFALL COVERAGE  
AND MORE SIGNIFICANT RAIN FOR NORTHEAST PR AND THE USVI AS BIT OF  
MOISTURE IS ADVECTED IN.  
 
IN TERMS OF RAINFALL AMOUNTS...THE ACTIVITY EXPECTED THIS  
AFTERNOON COULD PRODUCE ABOUT AN INCH OF RAIN OVER SOUTHWESTERN  
PR...BUT HIGHER ISOLATED AMOUNTS ARE POSSIBLE. THEN WEDNESDAY  
WOULD BE A BIT WETTER...WITH OVER 1.5 INCHES ACROSS SOUTHWEST PR  
IN THE FORECAST...THEN AROUND 0.75 INCHES ARE FORECAST FOR  
NORTHEASTERN PR...WHILE THE USVI ARE FORECAST TO OBSERVE AROUND A  
QUARTER OF AN INCH OF RAIN. DRIER CONDITIONS ARE FORECAST FOR  
THURSDAY ONWARD...BUT UNCERTAINTY STARTS TO INCREASE TOWARDS THE  
LATTER PART OF THE FORECAST PERIOD. THE LATEST MODEL GUIDANCE HAS  
CHANGED SIGNIFICANTLY WITH REGARDS TO THE TROPICAL STORM  
PHILIPPE...AND THE FORECAST BY THE NATIONAL HURRICANE CENTER HAS  
PHILIPPE TO THE NORTHEAST OF PR/USVI...WHICH WILL HAVE AN IMPACT  
ON THE LOCAL WEATHER.  
 
THE 5-DAY RAINFALL TOTAL IS FORECAST TO BE AROUND 3 INCHES ACROSS  
THE SOUTHWESTERN SECTIONS OF PR...NORTH EASTERN PR IS FORECAST  
AROUND 1.5 INCHES...WHILE THE USVI IS FORECAST 0.50 TO 1 INCH.  
 
ALAMO/ACOSTA...WPC (USA)  

 
 
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