325
FXCA62 TJSJ 270835
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
435 AM AST TUE OCT 27 2026
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 435 AM AST TUE OCT 27 2026
* HEAT: HOT AND HUMID CONDITIONS WILL PERSIST TODAY. A HEAT
ADVISORY IS IN EFFECT FOR PUERTO RICO AND THE U.S. VIRGIN
ISLANDS, WITH THE GREATEST HEAT IMPACTS EXPECTED ACROSS COASTAL
AND URBAN AREAS.
* FLOODING: SHOWERS AND ISOLATED THUNDERSTORMS MAY PRODUCE
LOCALLY HEAVY RAINFALL TODAY AND TONIGHT. THE GREATEST FLOODING
RISK IS ACROSS SOUTHERN AND SOUTHEASTERN PUERTO RICO, WHERE
REPEATED HEAVY RAINFALL COULD CAUSE URBAN AND SMALL STREAM
FLOODING. FLASH FLOODING REMAINS POSSIBLE.
* WEDNESDAY: AFTERNOON SHOWERS MAY PRODUCE PONDING ON ROADS AND
IN POORLY DRAINED AREAS, PARTICULARLY ACROSS INTERIOR AND
WESTERN PUERTO RICO. DRIER CONDITIONS ARE EXPECTED TO LIMIT
RAINFALL COVERAGE ON THURSDAY.
* BEACH AND COASTAL HAZARDS: DANGEROUS SURF AND LIFE-THREATENING
RIP CURRENTS CONTINUE ALONG EXPOSED NORTHERN BEACHES. HIGHER-
THAN- NORMAL TIDES, COMBINED WITH WAVE RUNUP, MAY CAUSE
LOCALIZED COASTAL FLOODING IN VULNERABLE AREAS AROUND HIGH TIDE
TODAY.
SHORT TERM(TODAY THROUGH THURSDAY)
ISSUED AT 435 AM AST TUE OCT 27 2026
MOSTLY CLEAR TO PARTLY CLOUDY SKIES PREVAILED OVERNIGHT ACROSS
EASTERN PUERTO RICO AND THE U.S. VIRGIN ISLANDS. FARTHER WEST,
CLOUDS AND THUNDERSTORMS MOVED FROM THE CARIBBEAN WATERS INTO
SOUTHWESTERN PUERTO RICO, PRODUCING PERIODS OF MODERATE TO LOCALLY
HEAVY RAIN. WINDS WERE MAINLY FROM THE SOUTHEAST, WITH LOCAL LAND
BREEZE VARIATIONS. TEMPERATURES REMAINED ABOVE TYPICAL OCTOBER
MINIMUM VALUES ACROSS MUCH OF THE REGION. MINIMUM READINGS SINCE
MIDNIGHT RANGED FROM THE MID-70S TO THE LOWER 80S ACROSS MANY
COASTAL AREAS, THE LOWER TO MID-80S ACROSS THE U.S. VIRGIN
ISLANDS, AND THE MID-60S TO 70S IN PUERTO RICO’S INTERIOR.
HIGH SURF CONTINUED OVERNIGHT ALONG NORTH-FACING BEACHES, WITH
BREAKING WAVES OF 8 TO 12 FEET REPORTED. EARLY THIS MORNING, THE
RINCON, ARECIBO, AND SAN JUAN BUOYS REPORTED SIGNIFICANT WAVE
HEIGHTS OF ABOUT 7, 5, AND 6 FEET, RESPECTIVELY, WITH A NORTHERLY
SWELL WITH PERIODS OF ABOUT 12 TO 13 SECONDS.
WARM AND HUMID CONDITIONS WILL PERSIST TODAY, WITH TEMPERATURES
RISING QUICKLY ACROSS COASTAL AND URBAN AREAS OF PUERTO RICO AND
THE U.S. VIRGIN ISLANDS. A HEAT ADVISORY IS IN EFFECT FOR THE
REGION. SOUTHEASTERLY WINDS WILL OCCASIONALLY CARRY SHOWERS INTO
WINDWARD AREAS, WITH ADDITIONAL SHOWERS EXPECTED THIS AFTERNOON
AND OVERNIGHT. THE GREATEST FLOODING RISK IS ACROSS SOUTHERN AND
SOUTHEASTERN PUERTO RICO, WHERE REPEATED OR PERSISTENT HEAVY
RAINFALL COULD CAUSE URBAN AND SMALL STREAM FLOODING. FLASH
FLOODING REMAINS POSSIBLE. ELSEWHERE, HEAVIER SHOWERS MAY RESULT
IN PONDING ON ROADS AND IN POORLY DRAINED AREAS.
THE RIDGE ALOFT MAY LIMIT CONVECTION COVERAGE AND DEPTH.
NEVERTHELESS, AVAILABLE MOISTURE, DAYTIME HEATING, SEA BREEZE
CONVERGENCE, AND TERRAIN EFFECTS MAY SUPPORT ISOLATED
THUNDERSTORMS. ANY DEVELOPING THUNDERSTORMS COULD PRODUCE
LIGHTNING AND LOCALLY HEAVY RAINFALL.
ADDITIONALLY, HIGHER-THAN-NORMAL SPRING TIDES COMBINED WITH HIGH
SURF MAY CAUSE LOCALIZED COASTAL FLOODING IN VULNERABLE, LOW-
LYING AREAS AROUND HIGH TIDE TODAY, PARTICULARLY ALONG EXPOSED
NORTHERN BEACHES AND ADJACENT COASTAL AREAS. WAVE RUNUP MAY WORSEN
FLOODING ALONG EXPOSED SHORELINES.
MODEL GUIDANCE PLACES PUERTO RICO AND THE U.S. VIRGIN ISLANDS
BETWEEN A TROUGH OVER THE WESTERN CARIBBEAN AND A RIDGE OVER THE
EASTERN CARIBBEAN THROUGH WEDNESDAY. ABOVE-NORMAL SEA SURFACE
TEMPERATURES AND A MOIST SOUTHERLY FLOW WILL KEEP CONDITIONS WARM
AND HUMID. ALTHOUGH MOISTURE IS EXPECTED TO DECREASE GRADUALLY,
PASSING SHOWERS AND AFTERNOON CONVECTION WILL REMAIN POSSIBLE,
SUPPORTED BY DAYTIME HEATING, SEA BREEZE CONVERGENCE, AND TERRAIN
EFFECTS. THE NWS ENSEMBLE FAVORS THE HIGHEST RAINFALL
ACCUMULATIONS ACROSS INTERIOR AND WESTERN PUERTO RICO ON
WEDNESDAY, WHERE HEAVIER SHOWERS COULD CAUSE PONDING ON ROADS AND
IN POORLY DRAINED AREAS.
BY THURSDAY, AN UPPER-LEVEL LOW MOVING NORTHWESTWARD NEAR THE
REGION MAY WEAKEN THE RIDGE. HOWEVER, THE GFS AND ECMWF INDICATE
LOWER PRECIPITABLE WATER AND MID-LEVEL MOISTURE THAN ON WEDNESDAY,
WHICH MAY LIMIT SHOWER COVERAGE DESPITE THE POTENTIAL REDUCTION IN
SUBSIDENCE. ENSEMBLE GUIDANCE ALSO FAVORS LOWER RAINFALL
ACCUMULATIONS ON THURSDAY. WARM CONDITIONS WILL CONTINUE,
PARTICULARLY ACROSS COASTAL AND URBAN AREAS.
LONG TERM(FRIDAY THROUGH TUESDAY)
ISSUED AT 435 AM AST TUE OCT 27 2026
SOME CHANGES WERE INTRODUCED TO THE LONG-TERM FORECAST, AS THE
WETTER AND UNSTABLE CONDITIONS MAY PERSIST EARLY NEXT WEEK. AS
MENTIONED IN THE PREVIOUS DISCUSSIONS, A SURFACE HIGH LINGERING OVER
THE CENTRAL ATLANTIC SHOULD MAINTAIN SOUTHEASTERLY WINDS ON FRIDAY
AND SATURDAY, BUT THE STEERING FLOW MAY WEAKEN AND TURN MORE
EASTERLY AS AN INDUCED TROUGH MOVES ACROSS THE REGION, SHIFTING BACK
FROM THE SOUTHEAST BY EARLY MONDAY.
THE WEATHER CONDITIONS ON FRIDAY MAY BE MARGINALLY UNSTABLE,
THOUGH THE LATEST MODEL GUIDANCE SUGGEST LINGERING DRY AIR IN THE
MID LEVELS THAT MAY LIMIT DEEP CONVECTION. ALTHOUGH SHOWERS AND
THUNDERSTORMS ARE EXPECTED FRIDAY AFTERNOON, FLOOD POTENTIAL WILL
LIKELY REMAIN LIMITED. SATURDAY ONWARDS, TROUGH DEEPENING INTO THE
TROPICS SHOULD STRENGTHEN, WEAKENING THE MID-LEVEL RIDGE, AND
DOMINATING THE WEATHER PATTERN ACROSS THE CWA. BASED ON THE LATEST
MODEL GUIDANCE, LOW AND MID-LEVEL MOISTURE SHOULD GRADUALLY
INCREASE ACROSS THE AREA, REACHING ABOVE-NORMAL LEVELS (> 60%) BY
SUNDAY AND MONDAY.
IN TERMS OF INSTABILITY, THE TROUGH SHOULD MAINTAIN COOL MID-
LEVEL TEMPERATURES (BETWEEN -6 AND - 8 C), WITH STEEP LAPSE RATES
AND DIVERGENCE ALOFT, ALLOWING CLOUD GROWTH AND ENHANCING DEEPER
CONVECTION ACROSS THE AREA. ADDITIONALLY, NCICS CFS CONTINUES TO
FORECAST THE APPROACH OF THE MJO OVER THE LOCAL AREA, WITH A
TRANSITION TO A MORE CONVECTIVE ENVIRONMENT ACROSS THE CARIBBEAN.
THEREFORE, SHOWERS AND THUNDERSTORMS CAN BE EXPECTED DURING THE
NIGHT AND MORNING HOURS SATURDAY ONWARD, BECOMING MORE FREQUENT ON
SUNDAY AND MONDAY, PARTICULARLY ACROSS THE U.S. VIRGIN ISLANDS
AND EASTERN/SOUTHEASTERN PUERTO RICO. AFTERNOON CONVECTION SHOULD
MAINLY CONCENTRATE ACROSS INTERIOR AND WESTERN/NORTHWESTERN PUERTO
RICO, INCLUDING THE SAN JUAN METRO AREA. RAINFALL ACCUMULATIONS
WILL LIKELY LEAD TO URBAN AND SMALL STREAM FLOODING, WITHOUT
RULING OUT LOCALIZED FLASH FLOOD, AND RAPID RIVER RISES. IN
ADDITION, THUNDERSTORMS COULD LEAD TO FREQUENT LIGHTNING AND GUSTY
WINDS.
AVIATION
(06Z TAFS)
ISSUED AT 435 AM AST TUE OCT 27 2026
MAINLY VFR CONDITIONS WILL PREVAIL. PASSING SHRA MAY CAUSE BRIEF
MVFR CONDITIONS AT WINDWARD TERMINALS. SHRA AND ISOLATED TSRA MAY
DEVELOP OVER PR THROUGHOUT THE DAY, ESPECIALLY IN THE AFTERNOON,
PARTICULARLY ACROSS THE INTERIOR AND SOUTHERN SLOPES, POTENTIALLY
CAUSING MVFR CONDITIONS AND MOUNTAIN OBSCURATIONS NEAR JPS AND
JBQ. LIGHT SE WINDS WILL CONTINUE THRU AROUND 27/13Z, THEN BETWEEN
10 AND 15 KT WITH SEA BREEZE VARIATIONS AFTER 27/13Z. PASSING
SHRA REMAIN POSSIBLE TONIGHT.
MARINE
ISSUED AT 435 AM AST TUE OCT 27 2026
A LONG-PERIOD NORTHERLY SWELL WILL CONTINUE SPREADING ACROSS THE
ATLANTIC WATERS AND LOCAL PASSAGES TODAY, BUILDING SEAS TO 6 TO 7
FEET THROUGH AT LEAST THIS EVENING. SURFACE HIGH PRESSURE OVER THE
CENTRAL ATLANTIC WILL PROMOTE MODERATE TO LOCALLY FRESH EAST- TO-
SOUTHEASTERLY WINDS ACROSS THE REGION THROUGH MIDWEEK. SMALL CRAFT
ADVISORIES REMAIN IN EFFECT FOR THE ATLANTIC OFFSHORE WATERS, THE
NORTHERN NEARSHORE WATERS, THE NORTHWESTERN NEARSHORE WATERS AND
THE MONA PASSAGE THROUGH 6 PM AST. STRONG SHOWERS AND ISOLATED
T-STORMS ARE FORECAST TO DEVELOP MAINLY OVER THE CARIBBEAN WATERS,
THE MONA PASSAGE, AND OFFSHORE ATLANTIC WATERS OVER THE NEXT FEW
DAYS.
BEACH FORECAST
ISSUED AT 435 AM AST TUE OCT 27 2026
A LONG-PERIOD NORTHERLY SWELL WILL CONTINUE TO DETERIORATE COASTAL
CONDITIONS ALONG MAINLY THE NORTH-FACING BEACHES OF PUERTO RICO,
CULEBRA, ST. THOMAS AND ST. JOHN. A HIGH SURF ADVISORY WILL
CONTINUE IN EFFECT FOR THE NORTHERN COASTLINE OF PUERTO RICO (FROM
RINCON TO FAJARDO) THROUGH 6 PM AST, AS BREAKING WAVES CAN REACH
7 TO 12 FEET, ESPECIALLY DURING THE MORNING TO EARLY AFTERNOON.
HIGH WAVES THAT CAN WASH OVER JETTIES AND SWEEP PEOPLE AND PETS
ONTO JAGGED ROCKS. ROUGH SURF MAY ALSO KNOCK YOU DOWN. LARGE
BREAKING WAVES WILL RESULT IN LOCALIZED BEACH/DUNE STRUCTURE
EROSION AND DANGEROUS SWIMMING CONDITIONS. MINOR COASTAL FLOODING
POSSIBLE, ESPECIALLY WITH THE SPRING TIDES TOMORROW MORNING.
A HIGH RISK OF RIP CURRENTS WILL BE IN EFFECT FOR THE NORTH-
FACING BEACHES OF PUERTO RICO, CULEBRA, ST. THOMAS AND ST. JOHN
THROUGH AT LEAST 6 AM AST WEDNESDAY. RIP CURRENTS CAN SWEEP EVEN
THE BEST SWIMMERS AWAY FROM SHORE INTO DEEPER WATER, WHERE IT
BECOMES DIFFICULT TO RETURN TO SAFETY. BEACHGOERS ARE STRONGLY
URGED TO STAY OUT OF THE WATER AT BEACHES UNDER THESE ADVISORIES
AND TO HEED ALL WARNING FLAGS, POSTED SIGNS, AND INSTRUCTIONS FROM
LIFEGUARDS AND LOCAL OFFICIALS.
PLEASE REFER TO THE LATEST COASTAL HAZARD MESSAGE (CFWSJU) FOR
UPDATES, THE MOST VULNERABLE AREAS AND FOR MORE INFORMATION.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HIGH RIP CURRENT RISK THROUGH LATE TONIGHT FOR PRZ001-002-005-
008-010-012.
HIGH SURF ADVISORY UNTIL 6 PM AST THIS EVENING FOR PRZ001-002-
005-008-010.
HEAT ADVISORY FROM 9 AM THIS MORNING TO 5 PM AST THIS AFTERNOON
FOR PRZ001>013.
VI...HEAT ADVISORY FROM 9 AM THIS MORNING TO 5 PM AST THIS AFTERNOON
FOR VIZ001-002.
HIGH RIP CURRENT RISK THROUGH LATE TONIGHT FOR VIZ001.
AM...SMALL CRAFT ADVISORY UNTIL 6 PM AST THIS EVENING FOR AMZ711-712-
741-742.
KEY MESSAGES/SHORT TERM/AVIATION...CAM
LONG TERM....MNG
MARINE/BEACH FORECAST...MRR
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