102
FXCA62 TJSJ 240843 CCA
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
335 AM AST SAT OCT 24 2026
...NEW KEY MESSAGES, SHORT TERM, LONG TERM, AVIATION, MARINE,
BEACH FORECAST...
KEY MESSAGES
ISSUED AT 335 AM AST SAT OCT 24 2026
* LIFE-THREATENING RIP CURRENTS WILL AFFECT EXPOSED BEACHES OF
NORTHERN, WESTERN, AND EASTERN PUERTO RICO, CULEBRA, AND ST.
THOMAS THROUGH LATE SUNDAY EVENING. ANOTHER NORTHERLY SWELL
ARRIVING MONDAY WILL RENEW HAZARDOUS SURF AND RIP CURRENTS INTO
THE WORKWEEK.
* HAZARDOUS SEAS UP TO 7 FEET WILL AFFECT PORTIONS OF THE
ATLANTIC WATERS AND MONA PASSAGE TODAY. A SMALL CRAFT ADVISORY
REMAINS IN EFFECT THROUGH NOON AST. BRIEF IMPROVEMENT SUNDAY
WILL PRECEDE ANOTHER INCREASE IN SEAS MONDAY.
* AFTERNOON SHOWERS AND THUNDERSTORMS WILL BRING LOCALIZED
FLOODING, LIGHTNING, AND GUSTY WINDS, PARTICULARLY ACROSS
INTERIOR AND WESTERN PUERTO RICO THROUGH MONDAY. DIFFERENCES IN
MOISTURE GUIDANCE LIMIT CONFIDENCE IN RAINFALL COVERAGE SUNDAY
AND MONDAY.
* ADDITIONAL SHOWERS AND THUNDERSTORMS TUESDAY WILL MAINTAIN THE
THREAT OF URBAN AND SMALL STREAM FLOODING AND RAPID RIVER RISES.
DRIER AIR FROM WEDNESDAY ONWARD SHOULD REDUCE RAINFALL
COVERAGE AND FLOODING POTENTIAL, ALTHOUGH ISOLATED AFTERNOON
THUNDERSTORMS WILL CONTINUE.
* WARM, HUMID CONDITIONS WILL PRIMARILY AFFECT PEOPLE SENSITIVE
TO HEAT AND THOSE OUTDOORS WITHOUT ADEQUATE HYDRATION OR
EFFECTIVE COOLING.
SHORT TERM(TODAY THROUGH MONDAY)
ISSUED AT 335 AM AST SAT OCT 24 2026
SUBSIDENCE LIMITED RAINFALL COVERAGE THROUGH MUCH OF THE NIGHT.
NEVERTHELESS, SUFFICIENT MOISTURE SUPPORTED PASSING SHOWERS OVER
THE LOCAL WATERS, THE U.S. VIRGIN ISLANDS, AND WINDWARD PUERTO
RICO, WITH SOME MOVING FARTHER INLAND. EAST TO SOUTHEAST WINDS
REMAINED AT 10 MPH OR LESS, WITH OCCASIONAL HIGHER GUSTS ACROSS
THE U.S. VIRGIN ISLANDS. OVERNIGHT TEMPERATURES REMAINED ABOVE
NORMAL ACROSS MUCH OF THE REGION.
MOISTURE AND INSTABILITY WILL SUPPORT AFTERNOON SHOWERS AND
THUNDERSTORMS TODAY, PARTICULARLY ACROSS INTERIOR, NORTHERN, AND
WESTERN PUERTO RICO. THE EVENING SAN JUAN SOUNDING MEASURED
PRECIPITABLE WATER NEAR 2.15 INCHES, CLOSE TO THE CLIMATOLOGICAL
REFERENCE SHOWN IN THE SUPPLIED ANALYSIS. BOTH GFS AND ECMWF
GUIDANCE MAINTAIN SUFFICIENT MOISTURE THROUGH TODAY, ALTHOUGH A
STABLE LAYER AND EXTENSIVE CLOUD COVER COULD LIMIT DAYTIME HEATING
AND CONVECTIVE COVERAGE. IF HEAVIER SHOWERS PERSIST OR REPEATEDLY
DEVELOP, LOCALIZED URBAN AND SMALL-STREAM FLOODING WILL REMAIN A
CONCERN. ISOLATED THUNDERSTORMS WILL ALSO BRING LIGHTNING AND
BRIEF GUSTY WINDS.
GUIDANCE DIVERGES ON MOISTURE AVAILABILITY SUNDAY AND MONDAY. THE
GFS MAINTAINS PRECIPITABLE WATER NEAR 2.0 TO 2.2 INCHES INTO
SUNDAY, WHILE THE ECMWF INTRODUCES DRIER AIR, WITH VALUES FALLING
TO AROUND 1.6 TO 1.8 INCHES BEFORE PARTIALLY RECOVERING MONDAY.
BOTH MODELS INDICATE RISING UPPER-LEVEL HEIGHTS, WARMING NEAR 500
MB, AND WEAKER LAPSE RATES THAN TODAY, SUGGESTING A LESS FAVORABLE
ENVIRONMENT FOR DEEP CONVECTION. HOWEVER, LINGERING MOISTURE,
DAYTIME HEATING, SEA BREEZE CONVERGENCE, AND TERRAIN EFFECTS WILL
CONTINUE TO SUPPORT AFTERNOON SHOWERS AND ISOLATED THUNDERSTORMS,
MAINLY ACROSS INTERIOR AND WESTERN PUERTO RICO. THE WETTER GFS
SOLUTION WOULD INCREASE THE THREAT OF LOCALIZED HEAVY RAINFALL,
WHILE THE DRIER ECMWF SOLUTION WOULD FAVOR REDUCED COVERAGE AND
SHORTER RAINFALL DURATION. PASSING SHOWERS WILL CONTINUE TO AFFECT
WINDWARD AREAS OVERNIGHT AND IN THE MORNING.
BOTH MODELS MAINTAIN ABOVE-NORMAL TEMPERATURES NEAR 925 MB THROUGH
MONDAY, SUPPORTING CONTINUED WARM AND HUMID CONDITIONS. HEAT
IMPACTS WILL PRIMARILY AFFECT SENSITIVE INDIVIDUALS AND THOSE
SPENDING EXTENDED PERIODS OUTDOORS WITHOUT ADEQUATE HYDRATION OR
EFFECTIVE COOLING.
LONG TERM(TUESDAY THROUGH SATURDAY)
ISSUED AT 335 AM AST SAT OCT 24 2026
WETTER CONDITIONS MAY PERSIST TUESDAY, THEN TRANSITION TO A SEASONAL
PATTERN WEDNESDAY ONWARD. A SURFACE HIGH PRESSURE BUILDING OVER THE
CENTRAL ATLANTIC SHOULD MAINTAIN A SE-S STEERING FLOW, THOUGH IT
WILL LIKELY REMAIN WEAK THROUGH MOST OF THE PERIOD AS THE LOCAL
PRESSURE GRADIENT WEAKENS DUE TO THE INTERACTION OF THE HIGH WITH A
DEEP-LAYERED TROUGH. THE TROUGH SHOULD ALSO INTERACT WITH A MID TO
UPPER-LEVEL RIDGE NORTHEAST OF THE REGION. THE LATEST MODEL GUIDANCE
SUGGESTS ABUNDANT MOISTURE CONTENT ACROSS THE REGION, WITH PWAT
VALUES REACHING WELL ABOVE CLIMATOLOGICAL NORMAL (UP TO 2.25
INCHES). ALTHOUGH LOW TO MID LEVELS RH REMAINS HIGH (ABOVE 60%), THE
LATEST SOLUTIONS SUGGEST THAT A PORTION OF THE PWAT IS ALSO
ASSOCIATED WITH HIGH CLOUDS ACROSS THE CWA. IF CLOUD COVER DOMINATES
DURING TUESDAY MORNING, THIS MAY INHIBIT DEEPER CONVECTION, WITH
MAINLY AN ADVECTIVE PATTERN OVER WINDWARD AREAS. OTHERWISE, SHOWERS
AND THUNDERSTORMS OVER THE MOUNTAIN RANGES OF PUERTO RICO MAY LEAD
TO URBAN AND SMALL STREAM FLOODING, WITHOUT RULING OUT RAPID RIVER
RISES.
WEDNESDAY ONWARDS, PWAT VALUES SHOULD DROP TO SEASONAL AND BELOW
NORMAL (BETWEEN 1.5 AND 1.75 INCHES), AS A DRIER SLOT FILTERS IN
THE MID LEVELS ON WEDNESDAY, FOLLOWED BY ANOTHER SLOT IN THE 850-
700 MB LAYER. ALTHOUGH THE RIDGE MAY LINGER NEAR THE AREA AND
BRING SUBSIDENCE ALOFT, THE COMBINATION OF DAYTIME HEATING, LOCAL
EFFECTS, SEA-BREEZE CONVERGENCE, AND AVAILABLE MOISTURE WILL BE
THE MAIN DRIVER OF CONVECTION EACH AFTERNOON, PARTICULARLY ACROSS
THE MOUNTAIN RANGES OF PUERTO RICO INTO NORTHERN/NORTHWESTERN
PORTIONS. ADDITIONALLY, DURING THAT PERIOD, THE VICINITY OF THE
MADDEN-JULIAN OSCILLATION (MJO) AND KELVIN WAVES MAY BOOST UPWARD
MOTION, AIDING DEEP CONVECTION. ALTHOUGH THE FLOODING RISK SHOULD
BE LOWER FROM WEDNESDAY ONWARDS DUE TO THE DRIER AIR, DURING THE
AFTERNOONS, ISOLATED THUNDERSTORMS COULD STILL PRODUCE GUSTY WINDS
AND LIGHTNING.
AVIATION
(06Z TAFS)
ISSUED AT 335 AM AST SAT OCT 24 2026
MAINLY VFR CONDITIONS WILL PREVAIL ACROSS THE TERMINALS. PASSING
SHRA WILL AFFECT EASTERN PR AND USVI TERMINALS THIS MORNING.
AFTERNOON SHRA/ISOLATED TSRA OVER INTERIOR AND WESTERN PR MAY
AFFECT TJBQ/TJSJ. BRIEF MVFR CONDITIONS, MOUNTAIN OBSCURATION, AND
GUSTY WINDS ARE EXPECTED NEAR CONVECTION. ACTIVITY WILL DIMINISH
THIS EVENING, WITH PASSING SHRA OVERNIGHT. ESE WINDS AROUND 10 KT,
WITH DAYTIME SEA BREEZE VARIATIONS AND HIGHER GUSTS NEAR
SHRA/ISOLD TSRA.
MARINE
ISSUED AT 335 AM AST SAT OCT 24 2026
A SURFACE HIGH-PRESSURE OVER THE CENTRAL ATLANTIC CONTINUES TO
PROMOTE MODERATE TO LOCALLY FRESH SOUTHEASTERLY WINDS ACROSS THE
REGION. A NORTHERLY SWELL CONTINUES TO SPREAD ACROSS THE LOCAL
WATERS, COMBINING WITH WIND-DRIVEN SEAS AND RESULTING IN SEAS UP
TO 7 FEET, PARTICULARLY ACROSS THE ATLANTIC WATERS AND MONA
PASSAGE. THESE CONDITIONS WILL CONTINUE TO PRODUCE CHOPPY AND
HAZARDOUS SEAS, ESPECIALLY ACROSS THE OFFSHORE ATLANTIC WATERS AND
EXPOSED PASSAGES. AS A RESULT, A SMALL CRAFT ADVISORY REMAINS IN
EFFECT THROUGH 12 PM AST SATURDAY. MARINE CONDITIONS ARE EXPECTED
TO BRIEFLY IMPROVE ON SUNDAY AS THE NORTHERLY SWELL GRADUALLY
SUBSIDES. HOWEVER, ANOTHER NORTHERLY SWELL IS EXPECTED TO ARRIVE
ACROSS THE LOCAL WATERS BY MONDAY, INCREASING SEAS ONCE AGAIN AND
MAINTAINING HAZARDOUS MARINE CONDITIONS ACROSS THE ATLANTIC WATERS
AND PASSAGES INTO THE UPCOMING WORKWEEK. SMALL CRAFT OPERATORS
SHOULD CONTINUE TO EXERCISE CAUTION, AS DETERIORATING MARINE
CONDITIONS MAY PERSIST THROUGH MUCH OF THE WORKWEEK.
BEACH FORECAST
ISSUED AT 335 AM AST SAT OCT 24 2026
A NORTHERLY SWELL CONTINUES TO SPREAD ACROSS THE LOCAL ATLANTIC
WATERS AND PASSAGES, MAINTAINING HAZARDOUS COASTAL CONDITIONS ACROSS
THE REGION. AS A RESULT, A HIGH RISK OF LIFE-THREATENING RIP
CURRENTS REMAINS IN EFFECT THROUGH LATE SUNDAY EVENING FOR THE
NORTHERN, WESTERN, AND EASTERN COASTAL AREAS OF PUERTO RICO,
INCLUDING CULEBRA AND ST. THOMAS. BREAKING WAVES ALONG EXPOSED
BEACHES WILL CONTINUE TO PRODUCE DANGEROUS SWIMMING CONDITIONS,
PARTICULARLY ALONG NORTH-FACING BEACHES.
COASTAL CONDITIONS ARE EXPECTED TO SLIGHTLY IMPROVE BY SUNDAY AS THE
NORTHERLY SWELL GRADUALLY SUBSIDES. HOWEVER, ANOTHER LONG-PERIOD
NORTHERLY SWELL IS EXPECTED TO ARRIVE ACROSS THE ATLANTIC WATERS BY
MONDAY, SPREADING TOWARD THE LOCAL ISLANDS AND RESULTING IN
DETERIORATING COASTAL CONDITIONS ONCE AGAIN. THIS ADDITIONAL SWELL
WILL LIKELY INCREASE BREAKING WAVE HEIGHTS AND MAINTAIN A HIGH RISK
OF LIFE-THREATENING RIP CURRENTS ALONG EXPOSED BEACHES INTO THE
UPCOMING WORKWEEK. BEACHGOERS ARE STRONGLY URGED TO AVOID ENTERING
THE WATER AT BEACHES EXPERIENCING HAZARDOUS SURF AND LIFE-
THREATENING RIP CURRENTS, AS THESE CONDITIONS CAN BE DANGEROUS EVEN
FOR EXPERIENCED SWIMMERS. ALWAYS FOLLOW LOCAL AUTHORITIES AND
LIFEGUARDS GUIDANCE.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HIGH RIP CURRENT RISK THROUGH LATE SUNDAY NIGHT FOR PRZ001-002-
005-008-010-012.
VI...HIGH RIP CURRENT RISK THROUGH THIS AFTERNOON FOR VIZ001.
AM...SMALL CRAFT ADVISORY UNTIL NOON AST TODAY FOR AMZ711-712-741.
KEY MESSAGES/SHORT TERM/AVIATION...CAM
LONG TERM....MNG
MARINE/BEACH FORECAST...LIS
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