696
FXCA62 TJSJ 250705
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
305 AM AST FRI SEP 25 2026
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 248 AM AST FRI SEP 25 2026
- SHOWERS AND THUNDERSTORMS WILL CONTINUE THIS AFTERNOON ACROSS
THE INTERIOR AND NORTHWESTERN PUERTO RICO. THEREFORE, THERE IS A
LIMITED TO ELEVATED FLOODING RISK ACROSS THESE AREAS TODAY.
- A HEAT ADVISORY IS IN EFFECT FROM 10 AM TO 3 PM AST FOR ALL OF
PUERTO RICO, INCLUDING VIEQUES, CULEBRA AND THE U.S. VIRGIN
ISLANDS.
- WARM TEMPERATURES ARE EXPECTED THIS WEEKEND ACROSS PUERTO RICO
AND THE U.S. VIRGIN ISLANDS. HEAT-SENSITIVE INDIVIDUALS SHOULD
AVOID OUTDOOR ACTIVITIES AND STAY HYDRATED.
- MOISTURE WILL GRADUALLY DECREASE OVER THE WEEKEND, LIMITING
SHOWERS AND THUNDERSTORMS TO LOCALIZED PORTIONS OF THE ISLANDS.
- A MODERATE RISK OF RIP CURRENTS IS EXPECTED TO CONTINUE ALONG
NORTHERN AND EASTERN BEACHES OF PUERTO RICO AND NORTHERN U.S.
VIRGIN ISLANDS THROUGH AT LEAST SATURDAY, INCREASING TO HIGH BY
SUNDAY INTO EARLY NEXT WEEK.
SHORT TERM(TODAY THROUGH SUNDAY)
ISSUED AT 248 AM AST FRI SEP 25 2026
OVERALL QUIET CONDITIONS PREVAILED ACROSS THE ISLANDS, WITH ONLY A
FEW PASSING SHOWERS MOVING ACROSS THE REGIONAL WATERS OVERNIGHT.
MINIMUM TEMPERATURES STAYED IN THE MID-70S TO LOW 80S ALONG COASTAL
AND URBAN AREAS, WHILE DROPPING INTO THE MID TO UPPER 60S IN THE
MOUNTAINS.
VARIABLE WEATHER CONDITIONS ARE ANTICIPATED ACROSS THE REGION AS WE
REMAIN UNDER THE INFLUENCE OF A TROPICAL UPPER-TROPOSPHERIC TROUGH
(TUTT) LINGERING NEARBY OVER THE NEXT FEW DAYS. AT THE SURFACE, A
HIGH-PRESSURE SYSTEM WILL MAINTAIN LIGHT TO MODERATE EAST-
SOUTHEASTERLY WINDS THROUGH MUCH OF THE PERIOD, SHIFTING TO EASTERLY
BY SUNDAY. PRECIPITABLE WATER (PWAT) VALUES WILL GRADUALLY DECREASE
TODAY TO NEAR OR SLIGHTLY BELOW NORMAL LEVELS OF 1.55 TO 1.70
INCHES. THIS WILL FAVOR MOSTLY FAIR WEATHER DURING THE MORNING, WITH
FEW PASSING SHOWERS ACROSS THE U.S. VIRGIN ISLANDS AND EASTERN
PUERTO RICO. AFTERNOON CONVECTION IS EXPECTED TO FOLLOW ACROSS THE
INTERIOR AND NORTHWESTERN PUERTO RICO. BECAUSE WINDS WILL REMAIN
LIGHT, ANY DEVELOPING SHOWERS OR THUNDERSTORMS COULD SPREAD TOWARD
NORTH-CENTRAL AND WESTERN PORTIONS OF THE ISLAND. AS A RESULT, THE
FLOODING RISK REMAINS LIMITED TO ELEVATED ACROSS NORTH-CENTRAL TO
NORTHWESTERN PUERTO RICO, WHERE URBAN AND SMALL-STREAM FLOODING IS
POSSIBLE, ESPECIALLY IN AREAS WITH SOILS ALREADY SATURATED FROM
RECENT RAINFALL.
SIMILAR CONDITIONS WILL PERSIST THROUGH SATURDAY. BY SUNDAY,
HOWEVER, PWAT VALUES WILL INCREASE TO SEASONAL VALUES WITH THE
ARRIVAL OF A TROPICAL WAVE. THE COMBINATION OF ENHANCED INSTABILITY
FROM THE TUTT, COOLER 500 MB TEMPERATURES (-8 TO -9°C), AND MOISTURE
FROM THE TROPICAL WAVE WILL SET THE STAGE FOR AN ACTIVE AFTERNOON,
BRINGING SHOWERS AND THUNDERSTORMS ACROSS INTERIOR AND WESTERN
PUERTO RICO, AS WELL AS SHOWERS OVER EASTERN PUERTO RICO.
IN ADDITION, AN ELEVATED HEAT THREAT CONTINUES TODAY FOR PUERTO RICO
AND THE U.S. VIRGIN ISLANDS DUE TO ABUNDANT MOISTURE, ABOVE-NORMAL
TEMPERATURES AND EAST-SOUTHEAST WINDS. MODEL GUIDANCE SUGGESTS 925
MB TEMPERATURES WILL GRADUALLY INCREASE THROUGH SUNDAY, PROLONGING
WARM AND HUMID CONDITIONS. AS A RESULT, A HEAT ADVISORY IS IN EFFECT
FOR PUERTO RICO AND THE U.S. VIRGIN ISLANDS FROM 10 AM TO 5 PM
TODAY. RESIDENTS AND VISITORS ARE URGED TO STAY HYDRATED, AVOID
STRENUOUS OUTDOOR ACTIVITIES DURING PEAK HEAT HOURS, TAKE FREQUENT
BREAKS IN SHADED OR AIR-CONDITIONED ENVIRONMENTS, WEAR LIGHT-
COLORED, AND NEVER LEAVE CHILDREN OR PETS UNATTENDED IN VEHICLES.
LONG TERM(MONDAY THROUGH FRIDAY)
ISSUED AT 248 AM AST FRI SEP 25 2026
NO MAJOR CHANGES TO THE LONG TERM FORECAST. A TROPICAL UPPER-
TROPOSPHERIC TROUGH (TUTT) WILL CONTINUE TO LINGER IN THE VICINITY
OF THE CWA. WHILE IT WILL SHIFT FROM THE NORTHEAST TO SOUTHEAST OF
THE ISLANDS BY LATE WEEK, THE POSITION WILL REMAIN UNFAVORABLE FOR
THE DEVELOPMENT OF SHOWERS AND THUNDERSTORM OVER THE FORECAST REGION
AS IT WILL FAVOR UPPER-LEVEL CONVERGENCE. THE LOW IS EXPECTED TO
MOVE AWAY FROM THE FORECAST AREA BY LATE NEXT WEEK. OVER THE EASTERN
ATLANTIC OCEAN A LOW-LEVEL HIGH PRESSURE SYSTEM WILL PROMOTE AN ENE
WIND FLOW WITH A SHIFT TO ESE FLOW BY THE END OF THE WEEK. THE
CONDITIONS ARE EXPECTED TO BECOME BREEZY TO LOCALLY WINDY ACROSS THE
US VIRGIN ISLANDS AND PUERTO RICO FROM MONDAY INTO LATE-WEEK. THE
POTENTIAL SHIFT IN WIND DIRECTION MAY AID IN THE DEVELOPMENT OF
STREAMERS FROM THE US VIRGIN ISLANDS, CULEBRA, VIEQUES, AND EL
YUNQUE RAINFOREST. WHILE A TROPICAL WAVE IS EXPECTED TO REACH THE
FORECAST REGION BETWEEN MONDAY AND TUESDAY THE BULK OF THE MOISTURE
FIELD ASSOCIATED WITH THE SYSTEM WILL REMAIN TO THE SOUTH OF THE US
VIRGIN ISLANDS AND PUERTO RICO WITH LOWER THAN AVERAGE PRECIPITABLE
WATER (PWAT) VALUES INTRUDING THE REGION. NONETHELESS, ON MONDAY THE
ATMOSPHERIC COLUMN IS EXPECTED TO BE MOISTER WHICH MAY BE FAVORABLE
FOR THE DEVELOPMENT OF CONVECTIVE ACTIVITY. DRY CONDITIONS IN THE
LOW-TO-UPPER LEVELS IS EXPECTED TO PERSIST INTO THE WEEK.
CONDITIONS FOR THE REMAINDER OF THE FORECAST PERIOD ARE THUS
EXPECTED TO BE DRIVEN BY LOCAL EFFECTS, PARTICULARLY FAVORING
AFTERNOON SHOWERS AND THUNDERSTORMS OVER THE NORTHWEST AND INTERIOR
OF PUERTO RICO AND SOME PASSING MORNING SHOWERS OVER THE US VIRGIN
ISLANDS AND EASTERN PUERTO RICO. MID-TROPOSPHERIC TEMPERATURES ARE
ALSO FORECASTED TO BE BELOW-TO-AROUND AVERAGE FOR THE SEASON,
INCREASING THE POTENTIAL FOR THE DEVELOPMENT OF DEEP CONVECTIVE
CELLS. RISKS ASSOCIATED TO EXTREME HEAT CONTINUE TO BE ONE OF THE
MAIN CONCERNS THROUGHOUT THE REST OF THE FORECAST PERIOD WITH 925 MB
TEMPERATURES EXPECTED TO BE 2 STANDARD DEVIATIONS ABOVE NORMAL
RANGES FOR THE SEASON INTO EARLY NEXT WEEK SHOWING A DECREASING
TREND INTO MID WEEK. CITIZENS ANDS VISITORS ARE INVITED TO STAY
ALERT OF THE EVOLVING WEATHER CONDITIONS AS WE MOVE INTO THE WEEKEND.
AVIATION
(06Z TAFS)
ISSUED AT 248 AM AST FRI SEP 25 2026
MAINLY VFR CONDS ARE EXPECTED ACROSS ALL TERMINALS DURING THE
FORECAST PERIOD. AFTN SHRA/TSRA DEVELOPMENT COULD RESULT IN VCTS
AT TJBQ/TJPS BTW 25/17-23Z. BRIEF PERIODS OF MVFR/IFR WITH MTN
OBSCURATIONS ARE POSSIBLE ACROSS CENTRAL AND WESTERN PR,
PARTICULARLY AT TJBQ AFT 25/17Z. WINDS LGT/VRB TO CALM THRU
25/14Z, BECOMING E-SE 10-15 KT WITH HIGHER GUSTS AND SEA BREEZE
VARIATIONS THRU 25/23Z, THEN BECOMING LGT/VRB OVERNIGHT.
MARINE
ISSUED AT 248 AM AST FRI SEP 25 2026
LIGHT TO MODERATE EAST TO SOUTHEAST WINDS WILL PREVAIL THROUGH
SATURDAY, GENERALLY AT 10 TO 15 KNOTS OR LESS, WITH SEAS MOSTLY
BETWEEN 2 AND 4 FEET. A WEAK NORTHERLY SWELL WILL CONTINUE TO SPREAD
ACROSS THE ATLANTIC WATERS AND PASSAGES, GRADUALLY INCREASING SEAS
THROUGH THE WEEKEND. MARINE CONDITIONS ARE EXPECTED TO DETERIORATE
FROM SUNDAY INTO EARLY NEXT WEEK AS THE NORTHERLY SWELL BECOMES MORE
PRONOUNCED AND EASTERLY WINDS STRENGTHEN, WITH SEAS BUILDING TO
AROUND 5 TO 6 FEET AND OCCASIONALLY UP TO 8 FEET ACROSS PORTIONS OF
THE OFFSHORE ATLANTIC WATERS BY MONDAY. SMALL CRAFT ADVISORY
CONDITIONS MAY BECOME POSSIBLE ACROSS THE ATLANTIC WATERS AND LOCAL
PASSAGES EARLY NEXT WEEK. SCATTERED SHOWERS WILL REMAIN POSSIBLE AT
TIMES, WITH ISOLATED THUNDERSTORMS CAPABLE OF PRODUCING LOCALLY
HIGHER WINDS AND SEAS, FREQUENT LIGHTNING, AND BRIEF REDUCTIONS IN
VISIBILITY.
BEACH FORECAST
ISSUED AT 248 AM AST FRI SEP 25 2026
A MODERATE RISK OF RIP CURRENTS WILL CONTINUE TODAY ALONG THE
NORTHERN AND NORTHEASTERN BEACHES OF PUERTO RICO AND CULEBRA,
WHILE A LOW RISK PREVAILS ELSEWHERE. THE MODERATE RISK WILL EXPAND
INTO PORTIONS OF NORTHWESTERN AND WESTERN PUERTO RICO AND THE
NORTHERN U.S. VIRGIN ISLANDS ON SATURDAY. SURF CONDITIONS ARE
EXPECTED TO BECOME INCREASINGLY HAZARDOUS SUNDAY INTO EARLY NEXT
WEEK AS A NORTHERLY SWELL REACHES THE LOCAL ATLANTIC WATERS, WITH
BREAKING WAVES GENERALLY INCREASING TO 5 TO 7 FEET ALONG THE
NORTHERN AND WESTERN BEACHES OF PUERTO RICO. THIS SWELL MAY RESULT
IN A HIGH RISK OF RIP CURRENTS ALONG THE MOST EXPOSED BEACHES
DURING THIS PERIOD.
OTHER BEACH HAZARDS WILL INCLUDE HEAT THROUGH THE WEEKEND,
ESPECIALLY DURING THE LATE MORNING AND AFTERNOON HOURS. AFTERNOON
SHOWERS AND ISOLATED THUNDERSTORMS WILL ALSO REMAIN POSSIBLE EACH
DAY, PARTICULARLY ALONG THE WESTERN BEACHES OF PUERTO RICO, WHERE
LIGHTNING, BRIEF HEAVY RAINFALL, AND LOCALLY GUSTY WINDS MAY OCCUR.
IF THUNDER IS HEARD, LEAVE THE BEACH AND WATER IMMEDIATELY AND SEEK
SAFE SHELTER.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HEAT ADVISORY FROM 10 AM THIS MORNING TO 3 PM AST THIS AFTERNOON
FOR PRZ001>013.
VI...HEAT ADVISORY FROM 10 AM THIS MORNING TO 3 PM AST THIS AFTERNOON
FOR VIZ001-002.
AM...NONE.
SHORT TERM...GRS
LONG TERM...MRR/RVM
MARINE/BEACH FORECAST...ICP
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