985  
FXCA62 TJSJ 070900  
AFDSJU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN JUAN PR  
500 AM AST MON JUL 7 2025  
   
KEY MESSAGES  
 
* NORMAL TO ABOVE-NORMAL TEMPERATURES WILL PERSIST, WITH A LIMITED  
HEAT RISK DAILY ACROSS LOWER ELEVATIONS AND URBAN AREAS, POSING  
RISKS TO VULNERABLE GROUPS.  
 
* AFTERNOON SHOWERS AND ISOLATED THUNDERSTORMS ARE LIKELY DAILY,  
DRIVEN BY LOCAL EFFECTS AND DIURNAL HEATING, EVEN DURING DRIER  
PERIODS. STAY ALERT FOR LIGHTNING AND SUDDEN DOWNPOURS.  
 
* BREEZY TO LOCALLY WINDY CONDITIONS WILL CAUSE CHOPPY SEAS AND A  
MODREATE RISK OF RIP CURRENTS OVER THE NEXT FEW DAYS. THESE MAY  
CREATE HAZARDOUS CONDITIONS. STAY CAUTONS AND FOLLOW SAFETY  
ADVISE.  
 
* MODERATE CONCENTRATIONS OF SAHARAN DUST ARE EXPECTED TO RETURN  
LATER THIS WEEK, RESULTING IN HAZY SKIES AND REDUCED VISIBILITY,  
WHICH MAY MINIMIZE OUTDOOR VISIBILITY AND AFFECT WEATHER  
OBSERVATIONS.  
 
 
   
SHORT TERM...TODAY THROUGH WEDNESDAY  
 
A VARIABLE WEATHER PATTERN PREVAILED DURING THE NIGHT INTO THE  
EARLY MORNING HOURS. DOPPLER RADAR DETECTED SOME PASSING SHOWERS  
OVER THE ATLANTIC WATERS OVERNIGHT. AS THE NIGHT PROGRESSED,  
ADDITIONAL SHOWERS WERE STEERED ACROSS THE REGION BY NORTHEASTERLY  
WINDS, AFFECTING NORTHERN AND NORTHEASTERN SECTIONS OF PUERTO  
RICO. AROUND 2 AM, ISOLATED TO SCATTERED SHOWERS WERE OBSERVED  
ACROSS THE METROPOLITAN AREA, IMPACTING MUNICIPALITIES SUCH AS  
CAROLINA, SAN JUAN, CANOVANAS, CATANO, BAYAMON, AND GUAYNABO.  
THESE SHOWERS DEVELOPED AS A RESULT OF COLD-AIR ADVECTION, WHICH  
ENHANCED SHALLOW CONVECTIVE ACTIVITY. RAINFALL ACCUMULATIONS WERE  
MINIMAL. WINDS WERE FROM THE EAST-NORTHEAST AT 10 MPH OR LESS.  
OVERNIGHT TEMPERATURES RANGED FROM THE MID TO UPPER 70S IN COASTAL  
AREAS TO THE UPPER 60S AND LOW 70S ACROSS THE MOUNTAINS.  
 
FOR THIS MORNING, A VARIABLE WEATHER PATTERN WILL PERSIST ACROSS  
THE ISLANDS AS WINDS MAINTAIN A NORTHEASTERLY COMPONENT. BY LATE  
MORNING, WINDS ARE EXPECTED TO SHIFT TO A MORE EASTERLY DIRECTION  
AS THE SURFACE HIGH PRESSURE SYSTEM EXTENDS INTO THE WESTERN  
ATLANTIC. AS THIS TRANSITION OCCURS, TRAPPED MOISTURE WITH  
PRECIPITABLE WATER VALUES BETWEEN 1.40 AND 1.60 INCHES WILL BE  
TRANSPORTED TOWARD THE ISLANDS BY THE PREVAILING FLOW. UNDER THIS  
PATTERN, ISOLATED TO SCATTERED SHOWERS ARE EXPECTED ACROSS COASTAL  
AREAS AND LOCAL WATERS IN THE MORNING, FOLLOWED BY INCREASED  
CONVECTIVE ACTIVITY OVER WESTERN AND INTERIOR PUERTO RICO IN THE  
AFTERNOON DUE TO LOCAL AND DIURNAL EFFECTS. WHILE THE U.S. VIRGIN  
ISLANDS SHOULD EXPERIENCE MOSTLY FAIR WEATHER, BRIEF TRADE WIND  
SHOWERS MAY DEVELOP, WITH LOCALIZED PONDING POSSIBLE IN AREAS  
WHERE SHOWERS BRIEFLY INTENSIFY.  
 
FROM TUESDAY INTO WEDNESDAY, THE UPPER-LEVEL RIDGE WILL SHIFT  
FARTHER EAST OF THE LEEWARD ISLANDS, LEAVING THE ISLANDS UNDER A  
STABLE PATTERN. THIS FEATURE WILL PROMOTE SUBSIDENCE ALOFT, ENHACING  
DRIER AIR ALOFT AND SUPPRESSING DEEP CONVECTION ACROSS THE REGION.  
HOWEVER, AT THE SURFACE, MOISTURE CONTENT WILL INCREASE AS A  
TROPICAL WAVE AND AN EASTERLY DISTURBANCE ENHANCE CONVECTIVE  
POTENTIAL ACROSS THE LOCAL FORECAST AREA. THESE COMBINED DYNAMICS  
WILL SUPPORT SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS  
EASTERN PUERTO RICO AND THE SURROUNDING WATERS BEGINNING TUESDAY  
EVENING, WITH ACTIVITY SPREADING INTO INTERIOR AREAS AND THE U.S.  
VIRGIN ISLANDS BY EARLY WEDNESDAY. ACCORDINGLY, THE FORECAST WAS  
ADJUSTED TO REFLECT AN INCREASE IN THE PROBABILITY OF ISOLATED TO  
SCATTERED SHOWERS BEGINNING AROUND 16Z TUESDAY OVER THE OFFSHORE  
NORTHEASTERN ATLANTIC WATERS, PROGRESSING INTO NORTHEASTERN PUERTO  
RICO, ST. THOMAS, AND ST. CROIX BY 20Z TUESDAY. THIS WILL LEAVE  
EARLY WEDNESDAY UNDER A VARIABLE WEATHER PATTERN WITH INCREASED  
CLOUDINESS AND PASSING SHOWERS. ADDITIONALLY, LOW CONCENTRATIONS  
OF SAHARAN DUST WILL BE PRESENT FROM TUESDAY AND CONTINUE INTO  
WEDNESDAY.  
   
LONG TERM...THURSDAY THROUGH MONDAY  
 
A WEAK TROPICAL WAVE IS EXPECTED TO MOVE THROUGH THE REGION ON  
THURSDAY, STEERED BY A STRONG BERMUDA-AZORES HIGH, MAINTAINING  
NEAR-NORMAL MOISTURE LEVELS. A SURFACE WIND SURGE WILL ARRIVE ON  
FRIDAY, INITIALLY ENHANCING LOW-LEVEL MOISTURE BEFORE A  
SIGNIFICANTLY DRIER AIR MASS SETTLES IN THROUGH THE WEEKEND. MID-  
TO UPPER-LEVEL DRY AIR AND A TRADE WIND CAP INVERSION—REINFORCED  
BY A TROPICAL UPPER-TROPOSPHERIC TROUGH (TUTT) TO THE  
NORTHEAST—WILL LIMIT DEEP CONVECTION DURING THIS PERIOD. MORE  
FAVORABLE CONDITIONS ARE LIKELY SUNDAY INTO EARLY NEXT WEEK AS THE  
TUTT SHIFTS OVER HISPANIOLA AND EASTERLY TRADE WIND DISTURBANCES  
APPROACH THE AREA.  
 
LINGERING MOISTURE WILL SUPPORT ISOLATED TO SCATTERED SHOWERS  
EARLY IN THE PERIOD, WITH SIGNIFICANT DRYING EXPECTED FROM FRIDAY  
THROUGH SUNDAY, REDUCING RAINFALL POTENTIAL. EVEN DURING THE  
DRIEST PERIODS, AFTERNOON CONVECTIVE DEVELOPMENT—DRIVEN BY DIURNAL  
HEATING AND LOCAL TERRAIN EFFECTS—REMAINS LIKELY EACH DAY. BREEZY  
TO WINDY CONDITIONS WILL PREVAIL THROUGH THE WEEKEND, WITH  
SOUTHEASTERLY WINDS SUPPORTING ABOVE-NORMAL TEMPERATURES,  
ESPECIALLY BETWEEN THURSDAY AND SATURDAY, WHEN VALUES ARE FORECAST  
TO EXCEED TYPICAL SEASONAL THRESHOLDS. COOLER AIR ALOFT MAY  
ARRIVE FRIDAY AND PERSIST INTO SATURDAY; HOWEVER, LIMITED MOISTURE  
WILL LIKELY PREVENT WIDESPREAD CONVECTION. RAIN CHANCES ARE  
EXPECTED TO INCREASE AGAIN FROM SUNDAY AFTERNOON INTO MONDAY.  
 
A SAHARAN AIR LAYER SPREADING OVER THE REGION BEGINNING THURSDAY  
WILL CONTRIBUTE TO HAZY SKIES, REDUCED VISIBILITY, AND CONTINUED  
SUPPRESSION OF WIDESPREAD CONVECTION THROUGH AT LEAST SATURDAY.  
WHILE EXCESSIVE RAINFALL IS NOT A CONCERN UNTIL SUNDAY, OTHER  
WEATHER HAZARDS—INCLUDING PERIODS OF EXCESSIVE HEAT, GUSTY WINDS,  
AND ISOLATED AFTERNOON LIGHTNING—REMAIN POSSIBLE THROUGHOUT THE  
LONG-TERM PERIOD.  
 
 
   
AVIATION  
 
(06Z TAF)  
 
VFR CONDITIONS WILL PERSIST FOR THE UPCOMING HOURS, WITH BRIEF  
MVFR CIGS ACROSS TJSJ AND TJBQ IN THE AFTERNOON HOURS DUE TO LOWER  
CEILINGS AND A REDUCTION IN VIS. WINDS WILL CONTINUE FROM THE  
E-NE AT 10 KNOTS, BACKING TO E AT AROUND 07/12Z, AND INCREASING UP  
TO 15 KNOTS WITH GUSTY WINDS. VCTS ARE FORECAST AT 07/18Z FOR  
TJBQ.  
 
 
   
MARINE  
 
MODERATE TO LOCALLY FRESH WINDS WILL CREATE CHOPPY SEAS ACROSS  
LOCAL WATERS OVER THE NEXT SEVERAL DAYS, PROMPTING CAUTION FOR  
SMALL CRAFT OPERATORS. 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 TUESDAY AND THURSDAY WITH THE PASSAGE OF TROPICAL  
WAVES. SAHARAN DUST IS EXPECTED TO RETURN LATER IN THE WORKWEEK.  
 
 
   
BEACH FORECAST  
 
WITH STRENGTHENING WINDS OVER THE NEXT SEVERAL DAYS, A MODERATE  
RIP CURRENT RISK IS EXPECTED TO GRADUALLY EXPAND ACROSS MOST LOCAL  
BEACHES—FROM NORTHWESTERN PUERTO RICO, CULEBRA, AND ST. CROIX  
TODAY, TO ALL OF NORTHERN PUERTO RICO, PARTS OF SOUTHEASTERN  
PUERTO RICO, AND VIEQUES BY TONIGHT. BEACHGOERS ARE ADVISED TO  
EXERCISE CAUTION, MAINLY ALONG EXPOSED NORTHERN AND EASTERN  
SHORELINES. FOR THE LATEST DETAILED UPDATES ON RIP CURRENT RISKS,  
PLEASE REFER TO THE SURF ZONE FORECAST (SRFSJU).  
 
 
   
SJU WATCHES/WARNINGS/ADVISORIES  
 
PR...NONE.  
VI...NONE.  
AM...NONE.  
 
 
 
 
SHORT TERM/AVIATION...LIS  
LONG TERM....ICP  
PUBLIC...ICP/LIS  
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