342  
FXCA62 TJSJ 080900  
AFDSJU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JUAN PR  
500 AM AST TUE JUL 8 2025  
   
KEY MESSAGES
 
 
* MODERATE TO HIGH CONCENTRATIONS OF SAHARAN DUST ARE EXPECTED TO  
RETURN DURING THE SECOND PART OF THE WORKWEEK, RESULTING IN HAZY  
SKIES, REDUCED VISIBILITY, AND POOR AIR QUALITY.  
 
* BREEZY CONDITIONS EXPECTED ON TUESDAY AND WEDNESDAY. CHOPPY SEAS  
AND A MODERATE RISK OF RIP CURRENTS WILL PERSIST OVER THE NEXT  
FEW DAYS. THESE MAY CREATE HAZARDOUS CONDITIONS.  
 
* DIURNALLY INDUCED AFTERNOON SHOWERS AND ISOLATED THUNDERSTORMS  
ARE EXPECTED OVER PORTIONS OF THE CORDILLERA CENTRAL AND WESTERN  
PR EACH DAY. PASSING SHOWERS WILL CONTINUE ACROSS THE USVI AND  
EASTERN SECTIONS OF PR DURING THE NIGHT/EARLY MORNING HOURS.  
 

 
   
SHORT TERM...TODAY THROUGH THURSDAY
 
 
PARTLY CLOUDY SKIES PREVAILED DURING THE OVERNIGHT HOURS ACROSS THE  
ISLANDS. PASSING SHOWERS WERE NOTED IN AND AROUND EASTERN, NORTHERN,  
SOUTHEASTERN PUERTO RICO, AND ACROSS ST. CROIX. THE DOPPLER RADAR  
ESTIMATED BETWEEN HALF TO THREE QUARTERS OF AN INCH OF RAIN WITH THE  
MOST PERSISTENT SHOWERS IN NORTHEASTERN AND SOUTHEASTERN PR. MINIMUM  
TEMPERATURES WERE FROM THE MID-60S TO LOW-70S ACROSS THE HIGHER  
ELEVATIONS OF PUERTO RICO TO THE UPPER 70S AND LOW 80S ACROSS THE  
LOWER ELEVATIONS OF THE ISLANDS. THE WIND WAS LIGHT FROM THE EAST,  
HOWEVER, GUSTS BETWEEN 20 AND 25 MPH WERE OBSERVED WITH THE SHOWERS.  
 
AN UPPER-LEVEL LOW OVER THE CENTRAL CARIBBEAN SEA AND AN UPPER-LEVEL  
RIDGE STRETCHING OVER THE AREA FROM THE TROPICAL ATLANTIC WILL  
CONTINUE TO BRIEFLY PROMOTE DIVERGENCE ALOFT TODAY. THIS IS LIKELY  
ENHANCING THE INTENSITY OF THE OVERNIGHT/EARLY MORNING SHOWERS, AND  
COULD CAUSE SOME SHOWERS TO GROW INTO SHORT-LIVED THUNDERSTORMS  
ACROSS THE LOCAL WATERS. MEANWHILE, A TROPICAL WAVE FAR SOUTH OF THE  
REGION WILL CONTINUE TO MOVE WEST AND AWAY OF THE AREA BY THIS  
EVENING. AT THE LOWER LEVELS, A BROAD RIDGE BUILDING FROM THE  
CENTRAL ATLANTIC WILL PROMOTE EAST TO SOUTHEAST WINDS FOR THE NEXT  
FEW DAYS. THE HIGHER MOISTURE CONTENT NEAR THE SURFACE AND THESE  
WINDS WILL PROMOTE NORMAL TO ABOVE NORMAL TEMPERATURES EACH DAY AND  
A LIMITED HEAT RISK WILL PERSIST FOR THE LOWER ELEVATIONS AND URBAN  
AREAS OF THE ISLANDS.  
 
A WIND SURGE WILL BRING SCATTERED SHOWERS AND STRONGER WINDS ACROSS  
THE AREA FROM TONIGHT THROUGH THURSDAY. ANOTHER TROPICAL WAVE WITH A  
BAND OF MOISTURE OF NEAR 2.00 INCHES OF PRECIPITABLE WATER CONTENT  
WILL STREAM ACROSS THE AREA ON THURSDAY. HOWEVER, HIGHER  
CONCENTRATIONS OF SAHARAN DUST MIXED WITH THE TROPICAL WAVE COULD  
HINDER WIDESPREAD CONVECTION DEVELOPMENT. HAVING SAID THAT, THE  
OVERALL AVAILABLE MOISTURE CONTENT IS FORECAST TO REMAIN AROUND  
NORMAL LEVELS, FLUCTUATING IN GENERAL BETWEEN 1.50-1.80 INCHES  
THROUGH AT LEAST THURSDAY AFTERNOON. THEREFORE, WE EXPECT A SIMILAR  
WEATHER PATTERN EACH DAY WITH PASSING SHOWERS ACROSS THE  
USVI/EASTERN HALF OF PR DURING THE NIGHT/EARLY MORNING HOURS,  
FOLLOWED BY DIURNALLY INDUCED AFTERNOON SHOWERS AND ISO  
THUNDERSTORMS OVER PORTIONS OF CENTRAL AND WESTERN PR, AND STREAMERS  
DEVELOPING DOWNWIND OF THE USVI AND FROM EL YUNQUE AREA. MOST OF  
THIS ACTIVITY ACROSS PR WILL CAUSE PONDING OF WATER ON ROADS AND  
POOR DRAINAGE AREAS, AND URBAN AND SMALL STREAM FLOODING WHERE  
THUNDERSTORMS DEVELOP.  
   
LONG TERM...FRIDAY THROUGH TUESDAY
 
 
THE INHERITED FORECAST REMAINS ON TRACK. THE LATEST MODEL GUIDANCE  
CONTINUES TO SUPPORT A SURFACE WIND SURGE CROSSING THE REGION ON  
FRIDAY, LEADING TO A BRIEF INCREASE IN LOW-LEVEL MOISTURE. THIS MAY  
SUPPORT ISOLATED TO SCATTERED SHOWERS EARLY IN THE DAY. HOWEVER, A  
SIGNIFICANTLY DRIER AIR MASS IS EXPECTED TO FILTER IN BY LATE FRIDAY  
AND CONTINUE THROUGH THE UPCOMING WORKWEEK, SUPPRESSING WIDESPREAD  
CONVECTION. AT THE SAME TIME, MID- TO UPPER-LEVEL DRY AIR AND A  
REINFORCING TRADE WIND INVERSION WILL FURTHER LIMIT VERTICAL CLOUD  
DEVELOPMENT. ADDITIONALLY, THE ARRIVAL OF A SAHARAN AIR LAYER  
WILL CONTRIBUTE TO HAZY SKIES, REDUCED VISIBILITY, AND POTENTIAL  
IMPACTS ON AIR QUALITY, ESPECIALLY FOR SENSITIVE GROUPS. THIS  
DUSTY AND DRY ENVIRONMENT WILL ALSO ACT TO SUPPRESS RAINFALL  
THROUGH SATURDAY. BREEZY TO WINDY CONDITIONS WILL PREVAIL BOTH  
FRIDAY AND SATURDAY, WITH EASTERLY WINDS SUPPORTING ABOVE-NORMAL  
TEMPERATURES, PARTICULARLY IN COASTAL AND URBAN AREAS.  
 
BY SUNDAY, THE TROPICAL UPPER-TROPOSPHERIC TROUGH (TUTT) IS FORECAST  
TO SHIFT WESTWARD TOWARD HISPANIOLA. THIS TRANSITION, COMBINED WITH  
THE APPROACH OF EASTERLY TRADE WIND DISTURBANCES, WILL BEGIN TO  
INCREASE ATMOSPHERIC MOISTURE OVER THE REGION. AS A RESULT, RAIN  
CHANCES WILL RISE ON SUNDAY AFTERNOON, WITH A MORE FAVORABLE  
ENVIRONMENT FOR CONVECTION.  
 
MONDAY AND TUESDAY WILL LIKELY FEATURE THE HIGHEST RAINFALL  
POTENTIAL AS DEEPER TROPICAL MOISTURE BECOMES ESTABLISHED ACROSS  
PUERTO RICO AND THE U.S. VIRGIN ISLANDS. SCATTERED SHOWERS AND  
THUNDERSTORMS ARE EXPECTED EACH AFTERNOON, ESPECIALLY IN WESTERN AND  
INTERIOR SECTIONS.  
ALTHOUGH THE THREAT OF EXCESSIVE RAINFALL REMAINS LOW UNTIL LATE  
SUNDAY INTO MONDAY, OTHER WEATHER CONCERNS.  
 

 
   
AVIATION
 
 
(06Z TAFS)  
 
MAINLY VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS ALL TERMINALS.  
HOWEVER, SHRA EN ROUTE FROM THE LEEWARD TERMINALS MAY CAUSE BRIEF  
PERIODS OF MVFR CIGS AND -RA. THEN, DIURNALLY INDUCED AFTERNOON TSRA  
OVER NORTHWESTERN PR SHOULD LEAD TO TEMPO MVFR CONDS AT TJBQ FM  
07/17-21Z. ELSEWHERE, MOSTLY VCSH AND BRIEF -RA PERIODS EXPECTED. HZ  
WILL GRADUALLY INCREASE DURING THE NEXT DAY OR SO, BUT VSBY SHOULD  
REMAIN P6SM. HOWEVER, HIGHER CONCENTRATIONS OF SAHARAN DUST RETURN  
FROM THURSDAY ONWARD AND VISIBILITIES COULD DROP TO 5-6 SM. WINDS  
WILL CONTINUE E-ESE AT 14-19 KT WITH SEA BREEZE VARIATIONS AND  
HIGHER GUSTS AFT 08/14Z.  
 

 
   
MARINE
 
 
MODERATE TO LOCALLY FRESH WINDS WILL CREATE CHOPPY SEAS ACROSS LOCAL  
WATERS OVER THE NEXT SEVERAL DAYS, SMALL CRAFT SHOULD EXERCISE  
CAUTION. SMALL CRAFT ADVISORIES WILL POSSIBLY BE ISSUED LATER ON FOR  
WEDNESDAY. AFTERNOON THUNDERSTORMS MAY IMPACT COASTAL WATERS AND  
LOCAL PASSAGES, PARTICULARLY OVER WESTERN PUERTO RICO AND THE MONA  
PASSAGE EACH DAY. SHOWERS AND THUNDERSTORM CHANCES INCREASE ON  
THROUGH THURSDAY WITH THE PASSAGE OF TROPICAL WAVES. SAHARAN DUST IS  
EXPECTED TO RETURN LATER IN THE WORKWEEK.  
 

 
   
BEACH FORECAST
 
 
INCREASING WINDS OVER THE NEXT SEVERAL DAYS WILL PROMOTE A  
MODERATE RISK OF RIP CURRENTS ACROSS THE EASTERN, NORTHERN, AND  
SOUTHEASTERN BEACHES OF PUERTO RICO, VIEQUES, CULEBRA, ST. THOMAS. AND  
ST. CROIX. LIFE- THREATENING RIP CURRENTS OFTEN OCCUR IN THE  
VICINITY OF GROINS, JETTIES, REEFS, AND PIERS.  
 

 
   
SJU WATCHES/WARNINGS/ADVISORIES
 
 
PR...NONE.  
VI...NONE.  
AM...NONE.  

 
 

 
 
SHORT TERM/AVIATION...DSR  
LONG TERM/MARINE/BEACH FORECAST...MMC  
 
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