937  
FXCA20 KWBC 021214  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
813 AM EDT MON OCT 02 2023  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI OCT 02/12UTC:  
TROPICAL STORM PHILIPPE IS STILL LOCATED JUST EAST OF THE LEEWARD  
ISLANDS. PHILIPPE WILL CAUSE PUERTO RICO AND THE U.S. VIRGIN  
ISLANDS TO BE UNDER A PERSISTENT NORTHEAST TO NORTHERLY WIND FLOW  
TODAY AND TUESDAY. AS PHILIPPE MOVES NORTH...THE LOCAL WINDS WILL  
BECOME WEAKER AND HAVE A STRONG WESTERLY COMPONENT...FROM  
NORTHWESTERN TO SOUTHWESTERN WINDS ON WEDNESDAY...THEN  
SOUTHWESTERN ON THURSDAY...BECOMING SOUTHERLY LATER ON FRIDAY AND  
THROUGH THE WEEKEND. THIS WIND PATTERN...COMBINED WITH THE  
AVAILABLE MOISTURE WILL HAVE AN IMPACT ON THE AMOUNTS AND LOCATION  
OF THE RAINFALL OVER PR/USVI. UNDER THE NORTHEASTERLY WINDS...THE  
MAX RAINFALL IS EXPECTED ACROSS NORTHEASTERN PR DUE TO SHOWERS IN  
BANDS WHILE AFTERNOON CONVECTION COULD AFFECT SOUTHWEST PR.  
TUESDAY IS EXPECTED TO HAVE A MUCH STRONGER NORTHERLY WIND  
COMPONENT...THEREFORE THE MAX RAINFALL IS EXPECTED ACROSS THE  
INTERIOR TO SOUTHERN PR IN THE AFTERNOON. AS WINDS SHIFT TO THE  
WEST ON WEDNESDAY...THE EASTERN HALF OF PR IS EXPECTED TO HAVE THE  
MORE SIGNIFICANT RAIN...WHILE WESTERN PR REMAINS RELATIVELY DRY.  
THURSDAY AND FRIDAY...UNDER SOUTHWESTERLY TO SOUTHERLY  
WINDS...WILL HAVE THE MAX RAINFALL ACROSS THE NORTHERN  
MUNICIPALITIES AS THE AFTERNOON SEA BREEZE CONVERGENCE COULD  
DEVELOP ACROSS THE NORTHERN COASTAL SECTIONS. WITH RESPECT TO THE  
USVI...MOST OF THE RAINFALL TODAY AND TUESDAY MAY BE DUE TO  
PASSING SHOWERS FROM OUTER BANDS OF PHILIPPE. HOWEVER...AS THE  
WINDS SHIFT TO THE WEST...AN AREA OF CONVERGENCE MAY OCCUR NEAR  
THE ISLANDS...ESPECIALLY ON WEDNESDAY...WHICH COULD CAUSE  
SIGNIFICANT RAIN ACROSS THE NORTHERN USVI. BRIEF SHOWERS WOULD BE  
EXPECTED ON THURSDAY AND FRIDAY ACROSS THE USVI AS WELL...THOUGH  
THURSDAY LOOKS A BIT WETTER THAN FRIDAY.  
 
THERE IS STILL CONSIDERABLE UNCERTAINTY IN THE RAINFALL FORECAST.  
THE LOCAL WIND DIRECTION AND SPEED...CONVERGENCE ZONES...AND  
AVAILABLE MOISTURE...ARE GREATLY INFLUENCED BY THE EVENTUAL TRACK  
OF TROPICAL STORM PHILIPPE...WHICH HAS BEEN A CHALLENGE IN ITSELF.  
THAT SAID...THE RAINFALL FORECAST AND REASONING IS BASED ON THE  
LATEST MODEL GUIDANCE AND THE TRACK FORECAST FOR PHILIPPE BY THE  
NATIONAL HURRICANE CENTER. IN ADDITION...THERE SEEMS TO BE A BIT  
MORE AGREEMENT AMONG THE MODEL GUIDANCE WITH REGARDS TO THE TRACK  
OF PHILIPPE.  
 
BASED ON THE CURRENT FORECAST...THE 5-DAY RAINFALL TOTAL IS  
FORECAST TO BE AROUND 3.5 TO 4 INCHES  
ACROSS THE NORTHERN TO NORTHEASTERN COASTAL SECTIONS OF PR...WHILE  
CENTRAL TO SOUTHWESTERN PR COULD OBSERVE BETWEEN 1.5 AND 2 INCHES.  
THE USVI ARE FORECAST AROUND 1 TO 2 INCHES...WITH THE NORTHERN  
ISLANDS ON THE HIGHER END OF THE RANGE.  
 
ALAMO...WPC (USA)  

 
 
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