685  
FXCA62 TJSJ 050841  
AFDSJU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JUAN PR  
441 AM AST SAT JUL 5 2025  
   
KEY MESSAGES  
 
* SAHARAN DUST PARTICLES WILL REMAIN ACROSS THE REGION RESULTING  
IN HAZY SKIES AT LEAST UNTIL MONDAY.  
 
* WARMER CONDITIONS ARE FORECASTED FOR TODAY WITH HEAT INDICES  
THAT WOULD RANK BETWEEN 100 TO 111 FAHRENHEIT DEGREES FROM 10  
AM TO 2 PM. AS A RESULT A HEAT ADVISORY IS IN EFFECT FOR ALL  
THE COASTAL AREAS OF PUERTO RICO, INCLUDING THE VICINITY OF  
CAGUAS.  
 
* THERE IS A LOW RISK OF RIP CURRENT FOR ALL THE COASTAL ALONG  
PUERTO RICO, CULEBRA, VIEQUES AND ST. THOMAS AND A MODERATE  
RISK OF RIP CURRENT ACROSS ST. CROIX.  
 
 
   
SHORT TERM...TODAY THROUGH MONDAY  
 
FAIR WEATHER WAS OBSERVED ACROSS THE ISLANDS DURING THE NIGHT HOURS.  
VERY BRIEF SHOWERS WERE OBSERVED ACROSS THE LOCAL WATERS, BUT  
WITHOUT IMPACT TO LAND AREAS. A SURFACE HIGH PRESSURE WILL MAINTAIN  
THE WIND FLOW FROM THE SOUTHEAST DURING THE WEEKEND, AND OUT OF THE  
EAST BY MONDAY, AT SPEEDS OF 14-19 KTS, WITH STRONGER GUSTS. IN THE  
FLOW, A DENSE SAHARAN AIR LAYER WILL PERSIST, RESULTING IN HAZY  
SKIES AND REDUCED VISIBILITIES. A TRADE WIND CAP INVERSION WILL BE  
PRESENT AT 850 MB TOO, WITH ANY LITTLE AVAILABLE MOISTURE TRAPPED IN  
THE LOWEST LEVEL OF THE ATMOSPHERE. THIS MOISTURE MAY RESULT IN A  
COUPLE OF BRIEF AND WEAK SHOWERS ACROSS EASTERN PUERTO RICO AND THE  
VIRGIN ISLANDS. EVEN IF CONDITIONS ARE NOT FAVORABLE FOR STRONG  
CONVECTION, AN ISOLATED, BUT STRONG, STORM MAY DEVELOP IN THE  
AFTERNOON ALONG THE NORTHWEST DUE TO STRONG DIURNAL HEATING.  
TEMPERATURES WILL REMAIN ABOVE NORMAL, WITH AN ELEVATED RISK OF HEAT  
FOR PUERTO RICO AND A LIMITED HEAT RISK FOR THE VIRGIN ISLANDS  
TODAY. EVERYONE SHOULD STAY HYDRATED, LOOK FOR SHADED AREAS AND  
AVOID STRENUOUS ACTIVITIES IN THE EXTERIOR.  
 
NOT MANY CHANGES ARE EXPECTED FOR SUNDAY, BUT BY MONDAY, THE HIGHER  
CONCENTRATION OF SAHARAN DUST WILL DEPART. A WEAK DISTURBANCE WILL  
MOVE INTO THE REGION, BRINGING PASSING SHOWERS INTO THE AREA, AND  
AIDING IN THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS THE  
INTERIOR AND WEST. ALTHOUGH NO WIDESPREAD SIGNIFICANT RAIN IS  
ANTICIPATED, SOME MINOR URBAN AND SMALL STREAM FLOODING COULD BE  
REPORTED. TEMPERATURES WILL BE JUST A TAD LOWER, BUT STILL WITH A  
LIMITED HEAT RISK ANTICIPATED FOR PUERTO RICO.  
   
LONG TERM...WEDNESDAY TROUGH SUNDAY  
 
 
A BROAD SURFACE HIGH PRESSURE ANCHORED ACROSS THE CENTRAL  
ATLANTIC WILL DOMINATE THE WEATHER PATTERN ACROSS PUERTO RICO AND  
THE U.S. VIRGIN ISLANDS FROM WEDNESDAY THROUGH SUNDAY. THIS  
FEATURE WILL PROMOTE SOUTHEASTERLY WINDS THROUGH SATURDAY,  
GRADUALLY SHIFTING TO AN EASTERLY FLOW LATE SATURDAY INTO SUNDAY  
AS THE HIGH EXTENDS WESTWARD INTO THE WESTERN ATLANTIC. AT MID TO  
UPPER LEVELS, A RIDGE PATTERN WILL ESTABLISH OVER THE REGION,  
PROMOTING INCREASINGLY STABLE CONDITIONS AND SUPPRESSING VERTICAL  
CLOUD DEVELOPMENT. AS A RESULT, SIGNIFICANT CONVECTION IS NOT  
EXPECTED DURING THE PERIOD, WITH ONLY BRIEF AND ISOLATED SHOWERS  
POSSIBLE ACROSS EASTERN AREAS DURING THE OVERNIGHT AND EARLY  
MORNING HOURS.  
 
A SURGE OF SAHARAN DUST WILL AFFECT THE ISLANDS FROM LATE  
WEDNESDAY THROUGH SUNDAY, LEADING TO HAZY SKIES AND FURTHER  
REDUCING SHOWER ACTIVITY. THE LATEST GUIDANCE FROM THE NASA  
GODDARD EARTH OBSERVING SYSTEM MODEL V5 SUGGESTS THAT THE HIGHEST  
CONCENTRATION OF SAHARAN DUST IS EXPECTED ON FRIDAY AND SUNDAY,  
WITH AEROSOL OPTICAL DEPTH VALUES RANGING BETWEEN 0.20 AND 0.30.  
THIS WILL RESULT IN THE DRIEST AND HAZIEST CONDITIONS DURING THOSE  
DAYS, MAINTAINING AN OVERALL PATTERN OF WARM, STABLE, AND MOSTLY  
DRY WEATHER THROUGH THE WEEKEND.  
 
 
   
AVIATION  
 
(06Z TAFS) VFR CONDITIONS EXPECTED TO PREVAIL THROUGH THE FORECAST  
PERIOD. HZ DUE TO SAHARAN DUST WILL PERSIST, BUT VIS REMAINING AT  
P6SM. TSRA EXPECTED AFTER 17Z FOR TJBQ, WITH PERIODS OF REDUCED VIS  
AND LOW CEILINGS. WINDS WILL BE FROM THE SE AT 14-17 KTS, AND  
STRONGER GUSTS.  
 
 
   
MARINE  
 
A BROAD SURFACE HIGH PRESSURE OVER THE CENTRAL ATLANTIC WILL  
CONTINUE TO RESULT IN MODERATE TO FRESH EASTERLY WINDS ACROSS THE  
REGION. THEREFORE, WIND-DRIVEN SEAS WILL RESULT IN CHOPPY MARINE  
CONDITIONS ACROSS THE ATLANTIC WATERS AND THE CARIBBEAN WATERS FOR  
THE FOLLOWING DAYS. SAHARAN DUST PARTICLES WILL BE IN PLACE AT  
LEAST UNTIL MONDAY, RESULTING IN HAZY SKIES AND LIMITED SHOWER  
ACTIVITY. VARIABLE WEATHER CONDITIONS WILL PERSIST FOR THE REST OF  
THE WEEKEND INTO THE UPCOMING WORKWEEK.  
 
 
   
BEACH FORECAST  
 
THERE IS A LOW RISK OF RIP CURRENT ACROSS ALL THE COASTAL AREAS OF  
PUERTO RICO INCLUDING CULEBRA AND VIEQUES AND ST. THOMAS.  
HOWEVER, FOR ST. CROIX THE RISK WILL GO UP TO MODERATE ACROSS THE  
EXPOSED BEACHES. FOR THE UPCOMING WORKWEEK THE RISK OF RIP  
CURRENT WILL BECOME MODERATE AGAIN ACROSS THE NORTHERN COASTAL  
AREAS OF PUERTO RICO AND EXTENDING INTO THE EAST AND SOUTHEAST ON  
TUESDAY.  
 
 
   
SJU WATCHES/WARNINGS/ADVISORIES  
 
PR...HEAT ADVISORY FROM 10 AM THIS MORNING TO 4 PM AST THIS AFTERNOON  
FOR PRZ001>005-007-008-010-011.  
 
VI...NONE.  
AM...NONE.  
 
 
 
 
SHORT TERM & AVIATION...ERG  
LONG TERM & MARINE....LIS  
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