385  
FXCA62 TJSJ 031829  
AFDSJU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JUAN PR  
229 PM AST THU JUL 3 2025  
   
KEY MESSAGES  
 
* SAHARAN DUST WILL PERSIST ACROSS THE REGION THROUGH AT LEAST  
EARLY MONDAY.  
 
* A TROPICAL WAVE WILL APPROACH THE AREA BY TOMORROW.  
 
* THE RIP CURRENT RISK WILL BECOME LOW FROM TOMORROW ONWARDS.  
 
 
   
SHORT TERM...TONIGHT THROUGH SATURDAY  
 
MOSTLY CALM WEATHER CONDITIONS PREVAILED ACROSS THE U.S. VIRGIN  
ISLANDS AND PUERTO RICO TODAY, WITH STREAMER-INDUCED SHOWERS  
DEVELOPING FROM CULEBRA AND VIEQUES, AFFECTING PARTS OF THE SAN JUAN  
METROPOLITAN AREA BY THE LATE MORNING. DURING THE AFTERNOON, DIURNAL  
HEATING AND LOCAL EFFECTS ALLOWED CONVECTION OVER NORTHWESTERN  
PUERTO RICO. WINDS WERE GENERALLY FROM THE EAST-SOUTHEAST AT 11 TO  
16 MPH, WITH OCCASIONAL HIGHER GUSTS. TEMPERATURES REACHED THE UPPER  
80S TO LOW 90S IN COASTAL AND URBAN AREAS, WHILE HIGHER ELEVATIONS  
AND RURAL ZONES STAYED IN THE UPPER 70S TO LOW 80S.  
 
LOOKING AHEAD, MODELS CONTINUE TO INDICATE A WEAK TROPICAL WAVE  
APPROACHING THE REGION BY FRIDAY (4TH OF JULY HOLIDAY). ALTHOUGH THE  
CORE OF THE WAVE IS EXPECTED TO REMAIN SOUTH OF PUERTO RICO AND THE  
U.S. VIRGIN ISLANDS, ENHANCED MOISTURE WILL MOVE ACROSS THE AREA.  
THIS WILL SUPPORT SCATTERED SHOWERS THROUGHOUT THE DAY, WITH  
AFTERNOON CONVECTION LIKELY ACROSS EASTERN PUERTO RICO, THE  
INTERIOR, AND WESTERN AREAS. A DENSE PLUME OF SAHARAN DUST IS  
FORECAST TO GRADUALLY ARRIVE BY FRIDAY AFTERNOON, BRINGING MODERATE  
TO HIGH CONCENTRATIONS ACROSS THE REGION THROUGH THE WEEKEND. AS A  
RESULT, LIMITED DEEP RAINFALL DEVELOPMENT, HAZY SKIES, REDUCED  
VISIBILITY, AND A DECLINE IN AIR QUALITY ARE EXPECTED. INDIVIDUALS  
WITH RESPIRATORY CONDITIONS SHOULD CLOSELY FOLLOW DEPARTMENT OF  
HEALTH GUIDANCE TO AVOID EXACERBATING SYMPTOMS. TEMPERATURES WILL  
CONTINUE TO TREND ABOVE NORMAL, WITH HEAT INDICES EXPECTED TO REACH  
HEAT ADVISORY CRITERIA, PARTICULARLY IN COASTAL AND URBAN AREAS.  
THEREFORE, RESIDENTS AND VISITORS ARE ADVISED TO STAY WELL HYDRATED,  
WEAR LIGHTWEIGHT AND BREATHABLE CLOTHING, AND AVOID PROLONGED  
EXPOSURE TO THE SUN BY TAKING FREQUENT BREAKS IN SHADED OR AIR-  
CONDITIONED AREAS. THESE PRECAUTIONS ARE ESPECIALLY IMPORTANT FOR  
THOSE PARTICIPATING IN OUTDOOR ACTIVITIES, AS THE COMBINATION OF  
HIGH HEAT AND DUSTY CONDITIONS CAN INCREASE THE RISK OF HEAT-RELATED  
ILLNESSES AND RESPIRATORY DISCOMFORT.  
 
OVERALL, SOME LOW-LEVEL MOISTURE WILL BE EMBEDDED IN THE DUST.  
THEREFORE, THE HOLIDAY WEEKEND WILL NOT BE COMPLETELY DRY.  
   
LONG TERM...SUNDAY THROUGH THURSDAY.  
 
A RELATIVELY VARIABLE WEATHER PATTERN IS FORECAST ACROSS THE  
REGION FROM SUNDAY THROUGH THURSDAY, INFLUENCED BY SEVERAL UPPER-  
LEVEL FEATURES, SURFACE PATTERNS, AND AN INTRUSION OF SAHARAN DUST  
BY THE BEGINNING OF THE PERIOD. ON SUNDAY, THERE WILL BE A SLIGHT  
PRESENCE OF INSTABILITY ALOFT DUE TO A CUT-OFF LOW LOCATED OVER  
HISPANIOLA THAT MIGHT RESULT IN MOISTURE ADVECTION ACROSS THE  
AREA. MEANWHILE, AT THE MID-LEVELS (500–700 MB), A RIDGE WILL HELP  
MAINTAIN A RELATIVELY STABLE ENVIRONMENT ALOFT. AT THE SAME TIME,  
A PLUME OF SAHARAN DUST IS EXPECTED TO MOVE OVER THE REGION, WITH  
CONCENTRATIONS CAPABLE OF REDUCING VISIBILITY BETWEEN 0.20 AND  
0.30 INCHES, RESULTING IN HAZY SKIES AND POSSIBLE AIR QUALITY  
DETERIORATION. OVERALL, SUNDAY APPEARS TO BE A QUIET DAY WITH HAZY  
SKIES AND LIMITED SHOWER DEVELOPMENT. HOWEVER, DAYTIME HEATING  
AND THE LOCAL MOUNTAINS WILL LEAD TO THE DEVELOPMENT OF AFTERNOON  
CONVECTION, PARTICULARLY IN THE INTERIOR AND WESTERN PARTS OF  
PUERTO RICO. SIMILAR ACTIVITY WILL BE POSSIBLE FOR THE U.S. VIRGIN  
ISLANDS IN ISOLATED AREAS, MOSTLY IN THE EVENING HOURS.  
 
BY MONDAY, ANOTHER CUT-OFF LOW WILL MIGRATE FROM THE NORTHEAST  
INTO THE NORTHERN PORTION OF THE REGION, FURTHER INCREASING  
MOISTURE LEVELS AND CLOUDINESS. THIS UPPER-LEVEL FEATURE WILL  
ENHANCE PATCHES OF CLOUDINESS AND MOISTURE, WHICH WILL BE  
TRANSPORTED WESTWARD BY THE PREVAILING EASTERLY TRADE WINDS. THE  
INTERACTION BETWEEN THIS FEATURE, SURFACE HEATING, AND LOCAL  
EFFECTS WILL RESULT IN SCATTERED SHOWERS AND ISOLATED AFTERNOON  
THUNDERSTORMS, MAINLY OVER THE INTERIOR AND WESTERN SECTIONS OF  
PUERTO RICO EACH DAY. TRADE WINDS WILL PERSIST FROM THE EAST UNDER  
THE INFLUENCE OF A BROAD SURFACE HIGH PRESSURE SYSTEM STALL OVER  
THE CENTRAL ATLANTIC. ON THURSDAY, THE PATTERN WILL REMAIN  
SIMILAR, WITH SOUTHEAST WINDS GRADUALLY TAKING HOLD AS A BROAD  
SURFACE HIGH OVER THE CENTRAL ATLANTIC EXTENDS FURTHER INTO THE  
CARIBBEAN. DAYS WILL REMAIN VARIABLE, WITH OCCASIONAL PASSING  
SHOWERS IN THE TRADE WIND FLOW DURING THE MORNING AND OVERNIGHT  
HOURS, FOLLOWED BY POCKETS OF AFTERNOON CONVECTION OVER INTERIOR  
AND WESTERN PUERTO RICO. SO FAR TODAY, ALTHOUGH MODEL HAD SOME  
HIGH LEVEL OF UNCERTAINTY, WEDNESDAY INTO THURSDAY WILL BE THE  
MOST UNSTABLE DAYS FOR THE LONG TERM PERIOD.  
 
 
   
AVIATION  
 
(18Z TAFS)  
 
VFR CONDITIONS ACROSS MOST TAF SITES. SHRA/TSRA WILL CONTINUE ACROSS  
INTERIOR AND NORTHWESTERN PR THROUGH 03/20Z, WITH BRIEF PERIODS OF  
LOW CEILINGS AND REDUCED VIS POSSIBLE AT TJBQ. SHOWERS WILL  
DIMINISH AFTER 03/23Z. E-SE WINDS AROUND 5-8 KTS AFTER WILL PREVAIL  
AFTER 23Z, INCREASING AFTER 04/13Z TO AROUND 10-15 KTS, WITH  
STRONGER GUSTS NEAR THE HEAVIEST SHOWER ACTIVITY.  
 
 
   
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.  
SAHARAN DUST PARTICLES WILL BE IN PLACE, RESULTING IN HAZY SKIES  
AND LIMITED SHOWER ACTIVITY UNTIL FRIDAY, WHEN ANOTHER TROPICAL  
WAVE MOVES INTO THE ISLANDS, BRINGING SHOWERS AND THUNDERSTORMS.  
 
 
   
BEACH FORECAST  
 
THE RIP CURRENT RISK WILL BECOME LOW BY FRIDAY AND WILL REMAIN  
LIKE IT THROUGH THE WEEKEND.  
 
 
   
SJU WATCHES/WARNINGS/ADVISORIES  
 
PR...HEAT ADVISORY UNTIL 4 PM AST THIS AFTERNOON FOR PRZ001>005-007-  
008-010-011.  
 
VI...NONE.  
AM...NONE.  
 
 
 
 
SHORT TERM/AVIATION...MMC  
LONG TERM...LIS  
PUBLIC DESK...CVB  
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