177  
FXCA62 TJSJ 011705  
AFDSJU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JUAN PR  
105 PM AST TUE JUL 1 2025  
   
KEY MESSAGES
 
 
* TRADE WIND SHOWERS WILL INCREASE TONIGHT ACROSS THE ISLANDS.  
 
* BREEZY WINDS WILL SUSTAIN CHOPPY SEAS AND MAINTAIN A MODERATE  
RISK OF RIP CURRENTS ALONG EXPOSED BEACHES OVER THE NEXT FEW  
DAYS.  
 
* A TROPICAL WAVE IS FORECAST TO INCREASE SHOWER ACTIVITY BY  
FRIDAY. HOWEVER, A STRONG SAHARAN AIR LAYER WITH MODERATE TO  
HIGH CONCENTRATIONS OF SAHARAN DUST IS EXPECTED TO MOVE WITH THE  
WAVE INTO THE WEEKEND.  
 

 
   
SHORT TERM...TONIGHT THROUGH THURSDAY
 
 
SUNNY TO PARTLY CLOUDY SKIES PREVAILED ACROSS THE ISLANDS THROUGHT  
THE DAY. AFTERNOON SHOWERS WERE DEVELOPING OVER THE SOUTHWESTERN  
QUADRANT OF PUERTO RICO, AND STREAMERS WERE DEVELOPING DOWNWIND  
OF THE U.S. VIRGIN ISLANDS. ADDITIONAL SHOWERS ARE EXPECTED LATER  
THIS EVENING AND TONIGHT AS A WIND SURGE WITH SHOWERS EMBEDDED IN  
THE TRADES REACH THE LOCAL AREA. MAXIMUM TEMPERATURES WERE FROM  
THE MID-80S TO THE LOW 90S ACROSS THE LOWER ELEVATIONS OF THE  
ISLANDS, AND FROM THE MID-70S TO LOW 80S ACROSS THE HIGHER  
MOUNTAINS OF PUERTO RICO. THE WIND WAS FROM THE EAST TO NORTHEAST  
BETWEEN 15 AND 20 MPH WITH SEA BREEZE VARIATIONS AND HIGHER GUSTS  
ACROSS COASTAL AREAS.  
 
A MID-LEVEL RIDGE NORTH OF THE AREA WILL CONTINUE TO MOVE WEST AND  
AWAY OF THE LOCAL AREA TODAY, WHILE A TRADE WIND PERTURBATION  
BRING AN ADDITIONAL MOISTURE CONTENT THROUGH WEDNESDAY MORNING.  
THIS WILL CAUSE MOSTLY PASSING SHOWERS ACROSS THE USVI AND EASTERN  
SECTIONS OF PR. THEREAFTER, A SURFACE HIGH PRESSURE WILL BUILD  
OVER THE CENTRAL ATLANTIC AND WINDS WILL TURN MORE ESE THROUGH AT  
LEAST THURSDAY. OVERALL FAIR WEATHER CONDITIONS ARE EXPECTED FOR  
THE REST OF THE SHORT-TERM PERIOD. HOWEVER, DIURNALLY INDUCED  
AFTERNOON SHOWERS ARE EXPECTED TO DEVELOP EACH DAY OVER WESTERN  
PR. A LIMITED HEAT RISK IS EXPECTED ACROSS MOST COASTAL AREAS AS  
DAYTIME TEMPERATURES REACH THE LOW 90S AND THE ABSENCE OF SAHARAN  
DUST WILL CAUSE RELATIVE HUMIDITIES TO INCREASE IN GENERAL ACROSS  
THE WESTERN, NORTHERN, AND EASTERN SECTIONS OF THE ISLANDS.  
 
   
LONG TERM...FRIDAY THROUGH TUESDAY
 
 
/FROM PREV DISCUSSION ISSUED AT 432 AM AST TUE JUL 1 2025/  
 
A WEAK TROPICAL WAVE WILL APPROACH THE ISLANDS ON FRIDAY. THE BULK  
OF THE WAVE WILL REMAIN OVER THE CARIBBEAN SEA, BUT ENOUGH  
MOISTURE SHOULD TRIGGER SOME SHOWERS OVER THE VIRGIN ISLANDS AND  
PUERTO RICO, WITH STRONGER CONVECTION DEVELOPING ACROSS WESTERN  
PUERTO RICO IN THE AFTERNOON. JUST LIKE THE LAST WAVE THAT MOVED  
OVER THE REGION, THIS ONE ALSO COMES WITH A LOT OF SAHARAN DUST,  
SO SKIES WILL BE HAZY LATE ON FRIDAY AND ON SATURDAY. LATER ON THE  
WEEKEND AND EARLY NEXT WEEK, A SERIES OF SURFACE TROUGHS WILL  
ALSO MOVE INTO THE REGION, BUT THEY WILL ALSO BE EMBEDDED IN  
SAHARAN DUST. THE PATTERN ALOFT WILL NOT FAVOR DEEP CONVECTION,  
BUT OCCASIONAL SHOWERS WILL MOVE INTO THE ISLANDS AT TIMES, WITH  
ADDITIONAL SHOWERS AND ISOLATED THUNDERSTORMS EACH AFTERNOON  
ACROSS THE WEST. THE WINDS WILL BE DRIVEN BY A SURFACE HIGH  
PRESSURE OVER THE EASTERN ATLANTIC, AT 10 TO 16 KTS. IT WILL BE  
HOT TOO, AS IT IS EXPECTED FOR JULY, WITH HEAT INDICES ABOVE 102  
DEGREES ALONG ALL COASTAL AND URBAN AREAS IN THE REGION.  
 

 
   
AVIATION
 
 
(18Z TAFS)  
 
VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS ALL TERMINALS  
THROUGH THE PERIOD. HOWEVER, QUICK PASSING -SHRA WILL MOVE AT  
TIMES ACROSS THE USVI/EASTERN PR TERMINALS DURING THE NIGHT. THIS  
MAY CAUSE BRIEF MVFR CONDS. THE 01/12Z TJSJ SOUNDING INDICATED ENE  
WINDS UP TO 26 KT BLO 4000 FT.  
 

 
   
MARINE
 
 
MARINERS CAN EXPECT CHOPPY SEAS ACROSS THE LOCAL ATLANTIC AND  
CARIBBEAN WATERS DUE PERSISTENT MODERATE TO FRESH EASTERLY WINDS.  
A WEAK TROPICAL WAVE IS FORECAST TO MOVE OVER THE LOCAL WATERS ON  
FRIDAY, INCREASING SHOWER AND THUNDERSTORM CHANCES. SAHARAN DUST  
WILL FOLLOW THE TROPICAL WAVE, WITH HAZY SKIES RETURNING QUICKLY  
THROUGH THE WEEKEND.  
 

 
   
BEACH FORECAST
 
 
A MODERATE RISK OF RIP CURRENTS (LIFE-THREATENING RIP CURRENTS  
ARE POSSIBLE IN THE SURF ZONE) ARE EXPECTED FOR MOST NORTHERN,  
EAST, AND SOUTHERN BEACHES OF PUERTO RICO, AS WELL AS FOR BEACHES  
OF CULEBRA, VIEQUES, SOUTHERN ST. JOHN, SOUTHERN ST. THOMAS AND  
ALL BUT WESTERN ST. CROIX.  
 
LIFE-THREATENING RIP CURRENTS OFTEN OCCUR IN THE VICINITY OF  
GROINS, JETTIES, REEFS, AND PIERS. UP TO A MODERATE RISK OF RIP  
CURRENTS WILL REMAIN FOR MOST OF THE PERIOD.  
 

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

 
 

 
 
DSR/MMC  
 
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