187  
FXCA62 TJSJ 090116  
AFDSJU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JUAN PR  
916 PM AST TUE JUL 8 2025  
   
UPDATE
 
 
A WIND SURGE APPROACHING THE REGION WILL PROMOTE CHOPPY SEAS AND  
CREATE HAZARDOUS CONDITIONS FOR SMALL CRAFT. HENCE, A SMALL CRAFT  
ADVISORY IS IN EFFECT FOR THE ATLANTIC OFFSHORE WATERS THIS  
EVENING AND THE NORTHERN WATERS OF THE ANEGADA PASSAGE FROM 8 AM  
AST WEDNESDAY MORNING THROUGH 8 PM AST WEDNESDAY EVENING. SMALL  
CRAFT SHOULD EXERCISE CAUTION IF NAVIGATING ACROSS THE REST OF  
THE LOCAL WATERS.  
 

 
   
PREV DISCUSSION
 
/ISSUED 200 PM 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 ARE EXPECTED THROUGH WEDNESDAY. CHOPPY SEAS  
AND A MODERATE RISK OF RIP CURRENTS WILL PERSIST OVER THE NEXT  
FEW DAYS. THESE MAY CREATE HAZARDOUS CONDITIONS ACROSS THE  
ATLANTIC WATERS.  
 
* 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...  
 
SUNNY TO PARTLY CLOUDY SKIES WERE OBSERVED ACROSS THE ISLANDS  
TODAY. DIURNALLY INDUCED SHOWERS AND ISOLATED THUNDERSTORMS WERE  
DEVELOPING OVER THE NORTHWEST QUADRANT OF PUERTO RICO EARLY THIS  
AFTERNOON, AND ARE EXPECTED TO CONTINUE OVER THE WESTERN WATERS OF  
PR THRU THIS EVENING. MAXIMUM TEMPERATURES WERE FROM THE  
UPPER-80S TO THE LOW 90S ACROSS THE LOWER ELEVATIONS OF THE  
ISLANDS, AND FROM THE MID-70S TO MID-80S ACROSS THE HIGHER  
MOUNTAINS OF PUERTO RICO. THE WIND WAS FROM THE EAST TO SOUTHEAST  
BETWEEN 16 AND 22 MPH WITH SEA BREEZE VARIATIONS AND HIGHER GUSTS  
BETWEEN 32 AND 37 MPH OBSERVED ACROSS COASTAL AREAS OF ALL THE  
ISLANDS.  
 
A WIND SURGE WILL BRING SCATTERED SHOWERS AND STRONGER WINDS ACROSS  
THE AREA FROM TONIGHT THROUGH WEDNESDAY. ANOTHER TROPICAL WAVE  
WITH A BAND OF MOISTURE OF 1.80 INCHES OF PRECIPITABLE WATER WILL  
STREAM ACROSS THE AREA ON THURSDAY. HOWEVER, HIGHER  
CONCENTRATIONS OF SAHARAN DUST MIXED WITH THE TROPICAL WAVE COULD  
HINDER SHOWER ACTIVITY IN GENERAL. 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 ISOLATED THUNDERSTORMS  
DEVELOPING 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.  
 
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. HIGHER CONCENTRATIONS OF SAHARAN DUST ON  
THURSDAY WILL PROMOTE HAZY CONDITIONS AND POOR AIR QUALITY.  
 
LONG TERM...FRIDAY THROUGH TUESDAY...  
 
/FROM PREV DISCUSSION ISSUED AT 500 AM AST TUE JUL 8 2025/  
 
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...  
 
(18Z TAFS)  
 
MAINLY VFR CONDITIONS ARE EXPECTED ACROSS ALL TERMINALS DURING  
THE NEXT 24 HOURS. HOWEVER, SHRA/TSRA EXPECTED TO DEVELOP IN AND  
AROUND TJBQ THRU 08/22Z. ACROSS THE USVI TERMINALS AND TJSJ,  
MOSTLY VCSH EXPECTED WITH BRIEF PERIODS OF -RA. THE 08/12Z TJSJ  
SOUNDING INDICATED ESE WINDS UP TO 27 KT BLO FL120. 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.  
 
MARINE...  
 
MODERATE TO FRESH TRADE 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...SMALL CRAFT ADVISORY UNTIL 8 PM AST WEDNESDAY FOR AMZ711.  
 
SMALL CRAFT ADVISORY FROM 8 AM TO 8 PM AST WEDNESDAY FOR AMZ723.  
 

 
 

 
 
SHORT TERM/AVIATION...MNG  
PUBLIC...MRR  
 
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