778  
FXCA20 KWBC 221248  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
847 AM EDT THU JUN 22 2023  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JUN  
22/12UTC: THE NATIONAL HURRICANE CENTER HAS TROPICAL STORM BRET  
PASSING OVER 200 MILES SOUTH OF PR/USVI FRIDAY EVENING.  
HOWEVER...A GRADUAL INCREASE IN MOISTURE IS FORECAST ON FRIDAY  
INTO SATURDAY. THE SHOWER ACTIVITY IS ALSO EXPECTED TO INCREASE  
ACROSS THE AREA...WITH EASTERN PR HAVING THE HIGHEST RAINFALL  
ACCUMULATION. THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES  
ON THE NEWLY FORMED TROPICAL DEPRESSION FOUR. ON THE FORECAST  
TRACK...TD FOUR WILL PASS OVER 250 MILES NORTHEAST OF ST JOHN ON  
MONDAY MORNING. ON THE FORECAST TRACK...LIGHTER WINDS COULD BE  
EXPECTED...AND A LINE OF DEEP MOISTURE COULD MOVE INTO THE LOCAL  
ISLANDS EARLY NEXT WEEK.  
 
A SURFACE HIGH PRESSURE IS MOVING INTO THE CENTRAL  
ATLANTIC...WHICH WILL KEEP A GENERAL EASTERLY WIND FLOW THROUGH  
THE REST OF THE WEEK...THOUGH THE WIND COULD BE SLIGHTLY STRONGER  
THIS EVENING INTO EARLY FRIDAY AS BRET PASSES SOUTH OF THE LOCAL  
AREA. AN UPPER TROUGH IS PASSING THROUGH THE AREA TODAY AND  
FRIDAY...AND ITS AXIS IS FORECAST TO BE EAST OF PR BY  
SATURDAY...THEN AN UPPER LEVEL RIDGE WILL MOVE IN LATE IN THE  
WEEKEND INTO EARLY NEXT WEEK. HOWEVER...ANOTHER TROUGH COULD  
DEVELOP EAST OF PR BY MIDWEEK. THE PRECIPITABLE WATER IS EXPECTED  
TO DECREASE TODAY...AS SOME DRY AIR AND SAHARAN DUST IS  
PRESENT...BUT WILL INCREASE GRADUALLY ON FRIDAY...REMAINING NEAR  
NORMAL THROUGH THE WEEKEND...ONLY BECAUSE THERE IS A NARROW BAND  
OF RELATIVELY DRY AIR NORTH OF TS BRET THAT IS FORECAST TO PERSIST  
OVER THE LOCAL ISLANDS. A SMALL SHIFT NORTH OF THE MOISTURE FIELD  
WOULD CAUSE PR/USVI TO HAVE ABOVE NORMAL MOISTURE THIS WEEKEND.  
THE PRECIPITABLE WATER IS EXPECTED TO DECREASE BY MONDAY  
AGAIN...THEN ANY INCREASE IN MOISTURE COULD DEPEND ON THE  
TRAJECTORY OF THE CURRENT TD 4.  
 
FOR TODAY...DUE TO THE MOISTURE DECREASE AND SAL...THE RAINFALL  
ACTIVITY IS EXPECTED TO BE A BIT MORE MODEST...WITH UNDER A HALF  
AN INCH OF RAIN ACROSS EASTERN PR...AND ONLY A SMALL AREA OF  
WESTERN PR HAVING A CHANCE OF SIGNIFICANT RAINFALL...WITH OVER ONE  
INCH OF RAIN IN THE FORECAST ACROSS AN ISOLATED SECTION. THE USVI  
IS EXPECTED TO HAVE MINIMAL RAIN TODAY. AS BRET MOVES SOUTH OF THE  
LOCAL ISLANDS...THE UNCERTAINTY IN THE RAINFALL FORECAST  
INCREASES...BUT AN INCREASE IN SHOWER ACTIVITY IS STILL EXPECTED  
ON FRIDAY AND THIS WEEKEND.  
 
THE FIVE-DAY FORECAST TOTALS INDICATE MAXIMA OF OVER 3 INCHES IN  
EASTERN AND WESTERN PUERTO RICO...MOST OF THAT RAINFALL OCCURRING  
FROM FRIDAY INTO SUNDAY. TOTALS BETWEEN 0.5 AND 1 INCH ARE  
FORECAST ACROSS THE USVI. ISOLATED HIGHER AMOUNTS ARE POSSIBLE.  
 
ALAMO...WPC (USA)  

 
 
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