729  
FXCA62 TJSJ 120838  
AFDSJU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JUAN PR  
438 AM AST SAT JUL 12 2025  
   
KEY MESSAGES  
 
* A LINGERING SAHARAN AIR LAYER (SAL) WITH MODERATE TO HIGH  
CONCENTRATIONS WILL CONTINUE TO PROMOTE HAZY SKIES, REDUCED  
VISIBILITIES AND POOR AIR QUALITY ACROSS PUERTO RICO AND THE  
U.S. VIRGIN ISLANDS THROUGH AT LEAST EARLY SUNDAY MORNING.  
 
* A HEAT ADVISORY IS IN EFFECT TODAY FOR ALL THE COASTAL AND URBAN  
AREAS OF PUERTO RICO, INCLUDING THE CAGUAS VALLEY AREA.  
 
* A TROPICAL WAVE WILL APPROACH THE ISLANDS BY THE MIDDLE OF THE  
WEEK, INCREASING MOISTURE AND THE POTENTIAL FOR SHOWERS AND  
THUNDERSTORMS.  
 
 
   
SHORT TERM...TODAY THROUGH MONDAY  
 
CLEAR TO PARTLY CLOUDY AND HAZY SKIES PREVAILED DURING THE EARLY  
MORNING HOURS ACROSS PUERTO RICO AND THE U.S. VIRGIN ISLANDS. BRIEF  
PASSING SHOWERS WERE NOTED OVER LAND AREAS ACROSS EASTERN PR AND THE  
USVI. HOWEVER, NO SIGNIFICANT RAINFALL AMOUNTS WERE OBSERVED.  
MINIMUM TEMPERATURES WERE FROM THE UPPER-70S TO LOW 80S ACROSS THE  
LOWER ELEVATIONS TO THE MID-60S AND UPPER 70S ACROSS THE HIGHEST  
ELEVATIONS. THE WIND WAS LIGHT FROM THE EAST TO NORTHEAST.  
 
A LINGERING SAHARAN AIR LAYER (SAL) WITH MODERATE TO HIGH  
CONCENTRATIONS WILL CONTINUE TO PROMOTE HAZY SKIES AND POOR AIR  
QUALITY ACROSS THE ISLANDS THROUGH AT LEAST EARLY SUNDAY MORNING.  
HOT TEMPERATURES ARE EXPECTED ONCE AGAIN AND A HEAT ADVISORY WILL BE  
IN EFFECT FROM 10 AM TO 5 PM TODAY ACROSS THE URBAN AREAS AND LOWER  
ELEVATIONS OF PUERTO RICO. RESIDENTS AND VISITORS, ARE ADVISED TO  
TAKE APPROPRIATE PRECAUTIONS DURING THIS PERIOD, PARTICULARLY THOSE  
WHO ARE SENSITIVE TO HEAT AND POOR AIR QUALITY CONDITIONS.  
 
A TUTT-LOW NORTH OF THE AREA TODAY WILL GRADUALLY MOVE WEST DURING  
THE REST OF THE PERIOD. THIS COULD ENHANCE THE DIURNALLY INDUCED  
AFTERNOON SHOWER ACTIVITY OVER WESTERN PR, WITH A SLIGHT INCREASE IN  
THE POTENTIAL FOR ISOLATED THUNDERSTORM DEVELOPMENT. HOWEVER, THE  
PRECIPITABLE WATER CONTENT IS EXPECTED TO REMAIN BELOW NORMAL LEVELS  
(~1.50 INCHES) UNTIL AT LEAST SUNDAY. ON MONDAY, A TRADE WIND  
PERTURBATION WILL MOVE ACROSS THE REGION, INCREASING SHOWER ACTIVITY  
IN GENERAL ACROSS THE ISLANDS.  
   
LONG TERM...TUESDAY THROUGH SATURDAY  
 
A TRADE WIND PERTURBATION IS EXPECTED TO ARRIVE INTO THE AREA ON  
TUESDAY, INCREASING MOISTURE INTO THE AREA AND THE POTENTIAL TO  
OBSERVE SHOWER ACTIVITY ACROSS THE ISLANDS. THE FORECAST HAVE NOT  
CHANGED A LOT WITH THE PREVIOUS MODEL GUIDANCE, AND CONTINUES TO  
SUGGEST THE ARRIVAL OF A BROAD TROPICAL WAVE BY MID-WEEK. THE LATEST  
PRECIPITABLE WATER CONTENT ANALYSIS SUGGEST VALUES UP TO 2.10 INCHES  
BY WEDNESDAY AFTERNOON. THEREFORE, SHOWERS AND THUNDERSTORMS ARE  
LIKELY OVER PORTIONS OF CENTRAL, WESTERN AND EASTERN PUERTO RICO,  
AND THE U.S. VIRGIN ISLANDS FROM WEDNESDAY MORNING THROUGH THE  
EVENING HOURS. THIS FAST MOVING WAVE IS EXPECTED TO EXIT THE REGION  
BY LATE WEDNESDAY, FOLLOWED BY A ATMOSPHERIC PERTURBATION ON  
THURSDAY.  
 
BY THE END OF THE WORKWEEK, A DRIER AIR MASS ACCOMPANIED BY ANOTHER  
PULSE OF SAHARAN AIR LAYER IS ANTICIPATED TO ARRIVE INTO THE AREA BY  
THURSDAY, FOLLOWING THE ATMOSPHERIC PERTURBATION PASSAGE OVER THE  
REGION. THIS EVENT WILL LIMIT THE SHOWER ACTIVITY ACROSS THE  
ISLANDS AND WILL PROMOTE HAZY SKIES, REDUCED VISIBILITIES AND  
DETERIORATED AIR QUALITY THROUGHOUT THE AREA UNTIL THE WEEKEND.  
 
HOT TEMPERATURES WILL CONTINUE ACROSS THE REGION NEXT WEEK. MAXIMUM  
TEMPERATURES ARE EXPECTED TO REMAIN IN THE UPPER 80S TO LOW 90S  
ALONG THE COASTAL AND URBAN AREAS, AND AROUND THE MID 80S IN THE  
HIGHER ELEVATIONS. HEAT INDICES COULD REACH VALUES ABOVE 105 DEGREES  
FAHRENHEIT EACH DAY, PARTICULARLY OVER THE NORTHERN, WESTERN AND  
SOUTHERN MUNICIPALITIES OF PUERTO RICO. RESIDENTS AND VISITORS,  
PLEASE BE AWARE OF THESE CONDITIONS AND PLAN ACCORDINGLY IF PLANNING  
TO DO OUTDOOR ACTIVITIES UNDER SUN EXPOSURE.  
 
 
   
AVIATION  
 
(06Z TAFS)  
 
MAINLY VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS ALL TERMINALS  
DURING THE NEXT 24 HOURS. HOWEVER, VCSH CANNOT BE RULED OUT ACROSS  
ALL SITES. HZ DUE TO SAHARAN DUST AND REDUCED VISIBILITIES BTW 6-8  
MILES EXPECTED. THIS MAY CAUSE FALSE BKN/OVC CIGS AT TIMES ACROSS  
THE USVI TERMINALS. WINDS WILL INCREASE FROM THE E-ENE AT 15-20 KT  
WITH SEA BREEZE VARIATIONS AND HIGHER GUSTS AFT 12/13Z.  
 
 
   
MARINE  
 
A SURFACE HIGH PRESSURE ACROSS THE CENTRAL ATLANTIC WILL CONTINUE TO  
PROMOTE SOUTHEASTERLY WINDS ACROSS THE REGION. THEREFORE, MARINERS  
CAN EXPECT MODERATE TO FRESH EASTERLY WINDS AND CHOPPY SEAS ACROSS  
THE ISLANDS THROUGH THE REST OF THE WEEKEND. HIGH SAHARAN DUST  
CONCENTRATIONS WILL CONTINUE TO MOVE ACROSS THE NORTHEASTERN  
CARIBBEAN THROUGH EARLY NEXT WEEK, PROMOTING HAZY SKIES, REDUCED  
VISIBILITIES AND DETERIORATED AIR QUALITY.  
 
 
   
BEACH FORECAST  
 
EXPECT A MODERATE RISK OF RIP CURRENTS ALONG THE NORTHERN AND  
EASTERN FACING BEACHES OF PUERTO RICO, CULEBRA AND ST. CROIX.  
 
PRECAUTIONS:  
 
SWIM ONLY NEAR LIFEGUARDS, HEED POSTED WARNINGS. CONDITIONS MAY QUICKLY  
BECOME DANGEROUS, ESPECIALLY FOR LESS EXPERIENCED SWIMMERS.  
 
HOT, HAZY CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE WEEKEND WITH  
HEAT INDEX VALUES LIKELY EXCEEDING THE 108°F IN URBAN AND COASTAL  
ZONES.  
 
SAFETY TIPS:  
 
STAY WELL HYDRATED. SEEK SHADE FREQUENTLY. AVOID OUTDOOR ACTIVITY  
DURING PEAK SUN HOURS (TYPICALLY 11AM–2PM).  
 
 
   
SJU WATCHES/WARNINGS/ADVISORIES  
 
PR...HEAT ADVISORY FROM 10 AM THIS MORNING TO 5 PM AST THIS AFTERNOON  
FOR PRZ001>005-007-008-010-011.  
 
VI...NONE.  
AM...NONE.  
 
 
 
 
SHORT TERM...DSR  
LONG TERM....GRS  
AVIATION...DSR  
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