907
FXCA62 TJSJ 230848 CCA
AFDSJU
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SAN JUAN PR
448 AM AST WED SEP 23 2026
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 100 AM AST WED SEP 23 2026
- A SEASONAL WEATHER PATTERN IS EXPECTED FOR THE NEXT COUPLE OF
DAYS ACROSS PUERTO RICO AND U.S. VIRGIN ISLANDS, WITH AFTERNOON
CONVECTION MAINLY OVER INTERIOR AND WESTERN PUERTO RICO. EXPECT
PONDING OF WATER OVER ROADS AND LANDSLIDES WHERE SOILS ARE
ALREADY SATURATED.
- HEAT-RELATED RISKS WILL CONTINUE EACH DAY, FRIDAY BEING OF THE GREATEST
CONCERN. HEAT-SENSITIVE INDIVIDUALS SHOULD AVOID OUTDOOR
ACTIVITIES AND STAY HYDRATED.
- INCREASED SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED ON
THURSDAY AS A TROPICAL WAVE APPROACHES THE ISLANDS, INCREASING
THE RISK OF URBAN AND SMALL STREAM FLOODING ACROSS THE ISLANDS,
ESPECIALLY IN THE AFTERNOONS.
- A MODERATE RIP CURRENT RISK WILL BE IN EFFECT TODAY, EXTENDING
THROUGH THE WEEKEND. THEREFORE, VISITORS AND CITIZENS ARE URGED
TO EXERCISE CAUTION, ESPECIALLY THOSE NORTHERN AND EAST FACING
BEACHES OF PR AND THE US VIRGIN ISLANDS.
SHORT TERM(TODAY THROUGH FRIDAY)
ISSUED AT 100 AM AST WED SEP 23 2026
OVERNIGHT, CONDITIONS REMAIN RELATIVELY CALM WITH POCKETS OF
SHOWERS MOVING ACROSS THE WATERS. TEMPERATURE REMAINED IN THE
UPPER 70S TO LOW 80S ALONG THE URBAN AND COASTAL AREAS OF THE
ISLANDS, WHILE ACROSS THE INTERIOR AND RURAL AREAS THEY DROPPED
INTO THE UPPER 60S TO LOW 70S.
DURING THE MORNING HOURS, EXPECT PASSING SHOWERS MAINLY OVER LOCAL
WATERS AND OCCASIONALLY REACHING EASTERN PORTIONS AND THE U.S.
VIRGIN ISLANDS AS PRECIPITABLE WATER (PWAT) WILL REMAIN WITHIN
SEASONAL LEVELS. SLIGHTLY DRIER AIR IN THE MID-TO-HIGH-LEVELS
SHOULD LIMIT SIGNIFICANT DEEP CONVECTION. HOWEVER, NEARBY TROUGHS,
LOCAL EFFECTS AND LOW-LEVEL MOISTURE SHOULD STILL SUPPORT BRIEF
CONVECTIVE PERIODS BY THE AFTERNOON HOURS. THAT BEING SAID, WITH
THE GENTLE TO MODERATE WINDS FROM AN EAST-SOUTHEASTERLY FLOW,
EXPECT THE SHOWER AND THUNDERSTORM ACTIVITY TO DEVELOP MAINLY OVER
INTERIOR TO NORTHWESTERN PORTIONS OF PUERTO RICO.
ON THURSDAY, A COUPLE OF MID-TO-UPPER-LEVEL LOWS APPROACHING FROM
THE NORTHEAST WILL INFLUENCE 500-MB TEMPERATURES TO DROP TO SUB-
SEASONAL LEVELS AND ENHANCE INSTABILITY IN THE UPPER LEVELS, WHICH
COULD RESULT IN DEEPER AFTERNOON CONVECTION. IN ADDITION, MOISTURE
ASSOCIATED TO A TROPICAL WAVE WILL REACH THE ISLANDS BY THURSDAY,
INCREASING THE POTENTIAL FOR DEEPER CONVECTION. THIS SCENARIO,
COMBINED WITH LOCAL EFFECTS AND PREVAILING GENTLE TO MODERATE WINDS
FROM THE ESE COULD ALLOW SHOWER AND THUNDERSTORM DEVELOPMENT
PRIMARILY OVER INTERIOR TO NORTHWESTERN PORTIONS, WHILE ISOLATED
ACTIVITY IS POSSIBLE OVER EASTERN PUERTO RICO, VIEQUES AND CULEBRA.
FOLLOWING THE TROPICAL WAVE, SLIGHTLY DRIER AIR WITH LOW
CONCENTRATIONS OF SAHARAN DUST WILL FILTER INTO THE CWA ON FRIDAY,
DROPPING PWAT VALUES TO NEAR NORMAL FRO THIS TIME OF THE YEAR.
THEREFORE, LESS SHOWERS AND THUNDERSTORMS ARE EXPECTED, BUT STILL
POSSIBLE DUE TO LOCAL EFFECTS AND SUFFICIENT MOISTURE LEVELS IN THE
LOW-LEVELS TO SUPPORT ISOLATED CONVECTION. AN ELEVATED HEAT RISK IS
LIKELY ON FRIDAY DUE TO LESS CLOUD COVER AND SHOWER ACTIVITY
EXPECTED, WHILE IT REMAINS LIMITED ON WEDNESDAY AND THURSDAY.
OVERALL, THE PRIMARY WEATHER HAZARDS WILL INCLUDE LOCALIZED HEAVY
RAINFALL, AND ISOLATED THUNDERSTORMS, WHICH COULD BE ACCOMPANIED BY
FREQUENT LIGHTNING AND STRONG GUSTS, PARTICULARLY ON THURSDAY. AN
ELEVATED RISK OF EXCESSIVE RAINFALL WILL REMAIN TODAY, MOSTLY
OVER INTERIOR AND NORTHWESTERN PUERTO RICO AS SATURATED SOILS AND
ELEVATED STREAMFLOWS PERSIST OVER THAT REGION. ANY ADDITIONAL
RAINFALL THIS AFTERNOON WILL RESULT IN EXCESSIVE RUNOFF THAT
COULD INCREASE THE FLOOD THREAT IN LOCALIZED AREAS. THE FREQUENCY
OF SHOWERS BY TONIGHT COULD INCREASE ACROSS WINDWARD COASTAL AREAS
OF THE FORECAST AREA AS THE LEADING EDGE OF A TROPICAL WAVE STARTS
TO MOVE OVER THE REGION. ELEVATED FLOODING THREAT WILL REMAIN ON
THURSDAY AS CONDITIONS BECOME MORE FAVORABLE FOR STRONGER
CONVECTION. CONSEQUENTLY, MAINLY TODAY AND THURSDAY, SHOWER
ACTIVITY MAY LEAD TO WATER PONDING ON ROADWAYS, URBAN AND SMALL
STREAM FLOODING, AND EVEN ISOLATED FLASH FLOODS WITH PERIODS OF
HEAVY RAINFALL, ALONGSIDE A CONTINUED RISK OF LANDSLIDES WHERE
TERRAIN IS ALREADY SATURATED FROM RECENT RAINFALL.
LONG TERM(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 100 AM AST WED SEP 23 2026
A COUPLE OF MULTI-LEVEL LOWS CONTINUE TO BE THE MAIN SYNOPTIC
FEATURES OVER THE REGION. AN UPPER-LEVEL LOW WILL SHIFT TO THE
SOUTHWEST OF PUERTO RICO AND COUPLED WITH LOCAL EFFECTS WILL
CONTINUE TO DRIVE INSTABILITY THAT FAVORS THE DEVELOPMENT OF SHOWERS
AND THUNDERSTORMS ACROSS THE CWA. WITH THE EXCEPTION OF SATURDAY,
WHEN MODEL GUIDANCE SUGGESTS THAT A DRIER AIR MASS FROM LOW TO UPPER
LEVELS (700-250 HPA) ACCOMPANIED WITH LOW LEVELS OF SAHARAN DUST
WILL LEAD TO AMENABLE WEATHER CONDITIONS. PRECIPITABLE WATER (PWAT)
VALUES ARE EXPECTED TO BE VARIABLE WITH LOWER VALUES EXPECTED
SATURDAY INTO SUNDAY, BECOMING SEASONAL ON MONDAY AND RETURNING TO A
DRIER PATTERN TUESDAY INTO WEDNESDAY. A KEY FEATURE FOR THE WEEKEND
WILL BE DRIER LOW-TO-UPPER LEVELS (700-250 MB). THUS, ANY ACTIVITY
THAT DEVELOPS WILL HEAVILY RELY ON THE INSTABILITY PROVIDED BY THE
LOW AS WELL AS MECHANICAL LIFTING MECHANISMS DRIVEN BY LOCAL
EFFECTS. A MORE HUMID VERTICAL PROFILE IS EXPECTED ON MONDAY MAKING
THE DAY MORE FAVORABLE FOR CONVECTIVE ACTIVITY. THE MID-TROPOSPHERIC
TEMPERATURES WILL BE WELL BELOW THE NORMAL RANGES FOR THE SEASON,
THUS THIS MAY FAVOR THE DEVELOPMENT OF DEEP CONVECTIVE CELLS INTO
EARLY NEXT WEEK. BREEZY CONDITIONS ARE EXPECTED TO PREVAIL ON
TUESDAY INTO WEDNESDAY, ALONG WITH THE ESE WINDFLOW SET BY THE LOW-
LEVEL LOW PRESSURE SYSTEM IN THE CENTRAL TO WESTERN ATLANTIC AND A
SURFACE HIGH OVER THE CENTRAL ATLANTIC SURROUNDING THE REMNANTS OF
FAY. THIS ESE FLOW MAY FAVOR THE DEVELOPMENT OF STREAMERS OFF THE US
VIRGIN ISLANDS, VIEQUES, CULEBRA, AND EL YUNQUE RAINFOREST AND
CONVECTIVE ACTIVITY FROM INTERIOR TO WEST AND NORTHWEST PR. ONE OF
THE MAIN RISKS FOR THE LONG-TERM PERIOD REMAINS ASSOCIATED TO THE
EXTREME HEAT. LOW-LEVEL (925 MB) TEMPERATURES ARE EXPECTED TO BE 2
STANDARD DEVIATIONS ABOVE NORMAL LEVELS, THIS ACCOMPANIED WITH HUMID
LOW-LEVELS AND CALMER WIND CONDITIONS WILL LEAD TO AN ELEVATED
EXTREME HEAT RISK INTO EARLY NEXT WEEK. THUS, WE RECOMMEND
INDIVIDUALS LIMIT OUTDOOR ACTIVITIES AND REMAIN WELL HYDRATED.
AVIATION
(06Z TAFS)
ISSUED AT 100 AM AST WED SEP 23 2026
ALL TAF SITES SHOULD EXPERIENCE VFR CONDITIONS PARTICULARLY BEFORE
23/16Z. HOWEVER, BRIEF PDS OF MVFR COND PSBL AFTER 23/17Z DUE TO
SHRA/TSRA DEVELOPMENT ACROSS INTERIOR AND WESTERN PR, POTENTIALLY
AFFECTING TJBQ, TJPS, AND TJSJ. PROB30 GROUPS WERE INCLUDED FOR TJBQ
AS CONFIDENCE SUPPORTS A CHANCE OF DIRECT TSRA IMPACTS. ELSEWHERE,
PASSING SH/VCSH. COND SHOULD GRADUALLY IMPROVE AFTER 23/21Z WITH
MAINLY VFR CONDITIONS PREVAILING. E TO ESE WINDS AT 10-15 KT ARE
EXPECTED AFTER 14Z, WITH LOCALLY HIGHER GUSTS NEAR THE HEAVIEST TS
ACT AND SEA-BREEZE VARIATIONS.
MARINE
ISSUED AT 100 AM AST WED SEP 23 2026
A SURFACE HIGH PRESSURE BUILDING ACROSS THE NORTH-CENTRAL ATLANTIC
WILL MAINTAIN LIGHT TO MODERATE EAST TO SOUTHEAST WINDS THROUGH THE
END OF THE WEEK. A SMALL, LONG-PERIOD NORTHEASTERLY SWELL WILL
GRADUALLY ARRIVE LATE TODAY, INCREASING SEAS TO 3 TO 4 FEET ACROSS
THE ATLANTIC AND CARIBBEAN WATERS, INCLUDING THE LOCAL PASSAGES.
ADDITIONALLY, EXPECT AFTERNOON THUNDERSTORMS TO DEVELOP OVER THE
ATLANTIC AND WESTERN COASTAL WATERS OF PUERTO RICO ALONG WITH
LOCALLY STRONG GUSTY WINDS, TORRENTIAL RAINFALL, FREQUENT LIGHTNING,
AND REDUCED VISIBILITY THROUGH THE EARLY EVENING HOURS EACH DAY.
SMALL CRAFT OPERATORS SHOULD USE ADDITIONAL CAUTION NEAR
THUNDERSTORMS, WHERE CONDITIONS CAN DETERIORATE QUICKLY. MARINERS
SHOULD MONITOR THE LATEST FORECASTS AND WEATHER CONDITIONS BEFORE
DEPARTURE AND WHILE UNDERWAY, AND BE PREPARED TO ADJUST PLANS IF
THUNDERSTORMS APPROACH.
BEACH FORECAST
ISSUED AT 100 AM AST WED SEP 23 2026
A LOW RISK OF RIP CURRENTS IS EXPECTED ACROSS MOST BEACHES OF PUERTO
RICO AND THE U.S. VIRGIN ISLANDS THROUGH THIS AFTERNOON, AS A SMALL
NORTHEASTERLY SWELL GRADUALLY REACHES THE ISLANDS AND INCREASE THE
RIP CURRENT RISK TO MODERATE ALONG NORTH- AND EAST-FACING BEACHES
FROM THIS AFTERNOON THROUGH THE END OF THE WORKWEEK AND POSSIBLY
INTO THE WEEKEND. AT A MODERATE RISK, STRONGER OR MORE FREQUENT RIP
CURRENTS CAN OCCUR, PARTICULARLY AT BEACHES EXPOSED TO THE INCOMING
SWELL. BEFORE ENTERING THE WATER, CHECK LOCAL BEACH CONDITIONS AND
AVOID AREAS WHERE RIP CURRENTS OR DANGEROUS SURF ARE OBSERVED.
THUNDERSTORMS MAY ALSO DEVELOP EACH AFTERNOON, BRINGING LIGHTNING
AND RAPIDLY CHANGING WEATHER CONDITIONS. IF THUNDER IS HEARD, LEAVE
THE BEACH AND WATER IMMEDIATELY AND SEEK SAFE SHELTER.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
SHORT TERM...MMC/JCP
LONG TERM....MRR/RVM
AVIATION/MARINE/BEACH FORECAST...MMC
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