765
FXCA62 TJSJ 290003
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
803 PM AST TUE OCT 28 2025
UPDATE
BEACH FORECAST
41043 BOUY DATA CONTINUES TO SHOW VALUES FROM 12 TO 16 SECONDS OF
SWELL PERIOD. THIS ENERGY WILL AFFECT THE NORTHERN COASTAL AREAS
TOMORROW DURING THE DAY WITH BREAKING WAVES BETWEEN 6 TO 7 FEET.
GIVEN THE EXPECTED CONDITIONS, THE HIGH RISK OF RIP CURRENT WAS
EXTENDED UNTIL 6 PM AST TOMORROW.
PREV DISCUSSION
/ISSUED 200 PM AST TUE OCT 28 2025/
.NEW SHORT TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES...
* QUIETER WEATHER AHEAD, WITH A MORE TYPICAL AFTERNOON PATTERN
AND LIMITED, LOCALIZED FLOOD, LIGHTNING, AND WIND RISKS.
* WARMER-THAN-NORMAL CONDITIONS EXPECTED MIDWEEK DUE TO LINGERING
MOISTURE AND SOUTHERLY WINDS.
* ROUGHER SEAS AND INCREASING RIP CURRENT RISKS FROM A
NORTHEASTERLY SWELL MIDWEEK, FOLLOWED BY ADDITIONAL PULSES OVER
THE WEEKEND AS SWELLS FROM HURRICANE MELISSA REACH THE AREA.
* U.S. VIRGIN ISLANDS: PASSING TRADE-WIND SHOWERS AND WARMER WEATHER,
WITH A HIGH RIP CURRENT RISK ALONG NORTH- AND EAST-FACING
BEACHES..
SHORT TERM...THIS EVENING THROUGH THURSDAY...
ISSUED AT 200 PM AST TUE OCT 28 2025
SATELLITE AND RADAR IMAGERY THIS MORNING CONFIRMED A MUCH DRIER
ATMOSPHERE ACROSS PUERTO RICO AND THE U.S. VIRGIN ISLANDS, WITH
LIMITED SHOWER ACTIVITY AND INCREASINGLY CLEAR SKIES. THE 28/12Z
UPPER-AIR SOUNDING SUPPORTED THIS TREND, SHOWING NEARLY HALF AN
INCH LESS MOISTURE THAN YESTERDAY, CONSISTENT WITH THE DRYING SEEN
ALOFT. SO FAR, THROUGH LATE MORNING AND EARLY AFTERNOON, NO
THUNDERSTORMS HAVE BEEN OBSERVED, AND CONVECTIVE DEVELOPMENT HAS
BEEN MINIMAL. CLEARER SKIES HAVE ALLOWED FOR WARMER TEMPERATURES
AROUND 5 TO 6 DEGREES HIGHER THAN MONDAY THOUGH LOWER HUMIDITY HAS
KEPT HEAT INDICES BELOW EXTREME LEVELS. FOR THE REST OF THE
AFTERNOON, MOSTLY SUNNY TO PARTLY CLOUDY SKIES WILL PREVAIL, WITH
BRIEF SHOWERS POSSIBLE FROM THE COASTAL WATERS MOVING INTO
SOUTHERN AND EASTERN PUERTO RICO, AND ONE OR TWO THUNDERSTORMS
DEVELOPING LATER OVER THE NORTHWESTERN SECTIONS.
AS HURRICANE MELISSA MOVES NORTHEASTWARD, ITS INFLUENCE ACROSS
THE LOCAL AREA WILL GRADUALLY WANE. STILL, VEERING SOUTHEASTERLY
WINDS WILL CONTINUE TO DRAW TROPICAL MOISTURE ACROSS THE ISLANDS,
WHILE A STRENGTHENING MID- TO UPPER-LEVEL RIDGE PROMOTES DRYING
AND INCREASED STABILITY ALOFT. THIS SETUP WILL FAVOR MOSTLY FAIR
WEATHER TONIGHT, WITH ONLY ISOLATED TO SCATTERED SHOWERS AND
PERHAPS ONE OR TWO THUNDERSTORMS OVER THE U.S. VIRGIN ISLANDS AND
THE SOUTHERN AND EASTERN PORTIONS OF PUERTO RICO. FLOODING
IMPACTS, IF ANY, WILL BE VERY LOCALIZED. RISKS: LIMITED.
CONFIDENCE: HIGH.
FROM WEDNESDAY THROUGH THURSDAY NIGHT, THE RIDGE WILL STRENGTHEN
AND BECOME THE DOMINANT SYNOPTIC FEATURE, FURTHER ERODING MID- TO
UPPER-LEVEL MOISTURE. WINDS WILL CONTINUE TO VEER, BECOMING
SOUTHERLY ON THURSDAY BEFORE SHIFTING EAST-SOUTHEASTERLY THURSDAY
NIGHT AS SURFACE RIDGING DEVELOPS. THIS WILL FAVOR A MORE TYPICAL
TRADE-WIND PATTERN WITH BRIEF MORNING SHOWERS OVER WINDWARD AREAS
AND AFTERNOON CONVECTION OVER THE INTERIOR AND NORTHWESTERN PUERTO
RICO FOLLOWING THE PREVAILING FLOW. FLOODING AND LIGHTNING RISKS
WILL REMAIN LIMITED TO LOCALLY ELEVATED, WITH LOW TO MODERATE
CONFIDENCE IN RAINFALL COVERAGE. IN CONTRAST, EXTREME HEAT RISKS
ARE EXPECTED TO BE ELEVATED, WITH MODERATE TO HIGH CONFIDENCE,
PARTICULARLY ACROSS COASTAL AND URBAN ZONES WHERE HEAT ADVISORIES
MAY BECOME NECESSARY.
LONG TERM...FRIDAY THROUGH TUESDAY...
FROM PREVIOUS DISCUSSION...ISSUED AT 321 AM AST TUE OCT 28 2025
THE CURRENT LONG-TERM FORECAST REMAINS ON TRACK. THE REGIONAL
WEATHER WILL BE INFLUENCED BY THE TRAILING MOISTURE ASSOCIATED WITH
HURRICANE MELISSA, WHICH BY NEXT WEEK IS EXPECTED TO BE LOCATED WELL
TO THE NORTH OF THE FORECAST AREA. WHILE THE BULK OF THIS MOISTURE
IS EXPECTED TO REMAIN OVER THE MONA CHANNEL AND NEAR HISPANIOLA,
SUFFICIENT RESIDUAL MOISTURE, WHEN COMBINED WITH DAYTIME HEATING AND
LOCALIZED EFFECTS, IS ANTICIPATED TO SUPPORT THE DEVELOPMENT OF
SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE REGION, PRIMARILY
DURING THE AFTERNOON HOURS. AT THE SURFACE, A DOMINANT HIGH-PRESSURE
SYSTEM WILL MAINTAIN AN EAST TO SOUTHEAST WIND FLOW ACROSS THE AREA
THROUGH THE BEGINNING OF NEXT WEEK.
A SIGNIFICANT SHIFT IN CONDITIONS IS EXPECTED FROM LATE SATURDAY
INTO SUNDAY WITH THE APPROACH OF A TROPICAL WAVE FORECAST TO REMAIN
SOUTH OF THE ISLANDS. THE NORTHERN PERIPHERY OF THIS WAVE WILL
INCREASE MOISTURE, THEREFORE, INCREASING THE POTENTIAL FOR SHOWERS
AND THUNDERSTORMS, PARTICULARLY OVER THE CENTRAL MOUNTAIN RANGE AND
THE WESTERN PORTIONS OF THE ISLANDS. MODEL GUIDANCE INDICATES THAT
PRECIPITABLE WATER (PWAT) VALUES WILL RISE TO ABOVE-NORMAL
CLIMATOLOGICAL LEVELS, RANGING BETWEEN 2.00 AND 2.25 INCHES DURING
THIS PERIOD.
FOLLOWING THE PASSAGE OF THE TROPICAL WAVE, A DRAMATIC CHANGE IS
EXPECTED ON MONDAY. PWAT VALUES ARE FORECAST TO DROP SHARPLY TO
BELOW-NORMAL LEVELS, NEAR 1.25 INCHES. THIS SIGNIFICANT DECREASE
SIGNALS THE INFLUX OF A MUCH DRIER AND MORE STABLE AIR MASS, DRIVEN
BY THE POSITIONING OF A HIGH-PRESSURE SYSTEM ACROSS ALL ATMOSPHERIC
LEVELS TO THE NORTH OF THE LOCAL AREA.
THROUGHOUT THE FORECAST PERIOD, EXPECT ELEVATED HEAT CONDITIONS
DRIVEN BY ABOVE-NORMAL TEMPERATURES AT THE 925 MB LEVEL. MAXIMUM
TEMPERATURES ALONG THE COASTAL AND URBAN AREAS ARE FORECAST TO RANGE
FROM THE MID TO UPPER 80S. COOLER CONDITIONS ARE EXPECTED IN THE
MOUNTAINOUS REGIONS, WHERE MAXIMUM TEMPERATURES WILL REMAIN IN THE
MID 70S TO LOW 80S.
AVIATION...
(18Z TAFS)
ISSUED AT 200 PM AST TUE OCT 28 2025
MAINLY VFR CONDS EXPECTED THRU PRD. BRIEF MVFR CONDS PSBL IN
SHRA/TSRA, WITH BRIEF REDNS IN VIS/CIGS MAINLY AFT 27/16-22Z,
AFFECTING TJBQ/TJSJ. TRADE-WIND SHRA WILL REMAIN PERSISTENT AT
TJSJ/USVI TERMINALS THRU PRD, PRODUCING BRIEF VIS/CIGS REDUCTIONS
AT TIMES. SFC WINDS SE 10–15 KT, BCMG LGT/VRB AFT 27/23Z UNDER
LAND-BREEZE INFLUENCE. HIGHER GUSTS PSBL NR SHRA/TSRA.
MARINE...
ISSUED AT 200 PM AST TUE OCT 28 2025
MODERATE EAST-SOUTHEASTERLY WINDS WILL PREVAIL TONIGHT, VEERING
SOUTHEAST ON TUESDAY AND SOUTH-SOUTHEAST BY WEDNESDAY AS MAJOR
HURRICANE MELISSA MOVES NORTHWARD. WINDS WILL INCREASE BY
WEDNESDAY NIGHT, BECOMING LOCALLY WINDY ACROSS THE ATLANTIC WATERS
AND CARIBBEAN PASSAGES DUE TO THE INTERACTION WITH A STRENGTHENING
ATLANTIC HIGH. MARINE CONDITIONS WILL REMAIN ROUGH, WITH A BROADER
AREA OF CONCERN FOR SMALL CRAFT BY MIDWEEK AS NORTHERLY SWELLS AND
STRONGER WINDS SPREAD ACROSS THE LOCAL WATERS. SMALL CRAFT SHOULD
EXERCISE CAUTION, PARTICULARLY ACROSS THE ATLANTIC WATERS AND
CARIBBEAN PASSAGES BY MIDWEEK. A SECOND SWELL EVENT GENERATED BY
HURRICANE MELISSA WILL AFFECT THE AREA OVER THE WEEKEND. SHOWERS
AND ISOLATED THUNDERSTORMS WILL AT TIMES CREATE ADDITIONAL
HAZARDS, INCLUDING GUSTY WINDS, LIGHTNING, AND LOCALLY HIGHER
SEAS.
BEACH FORECAST...
ISSUED AT 200 PM AST TUE OCT 28 2025
A MODERATE RISK OF RIP CURRENTS WILL PERSIST TONIGHT ACROSS MOST
BEACHES OF PUERTO RICO AND THE U.S. VIRGIN ISLANDS, WHERE LIFE-
THREATENING RIP CURRENTS REMAIN POSSIBLE. THE RISK WILL INCREASE
TO HIGH ON WEDNESDAY AND THURSDAY ALONG NORTH-FACING BEACHES OF
PUERTO RICO, CULEBRA, AND ST. CROIX, AS NORTHERLY SWELLS SPREAD
ACROSS THE LOCAL ATLANTIC WATERS AND PASSAGES, MAKING LIFE-
THREATENING RIP CURRENTS LIKELY FOR BEACHGOERS. A BRIEF
IMPROVEMENT IS EXPECTED THURSDAY NIGHT INTO FRIDAY, BEFORE
CONDITIONS DETERIORATE AGAIN DURING THE WEEKEND AS SWELLS FROM
HURRICANE MELISSA REACH THE AREA. IN ADDITION, SHOWERS AND
ISOLATED THUNDERSTORMS MAY LOCALLY WORSEN BEACH AND SURF
CONDITIONS, BRINGING GUSTY WINDS, DANGEROUS LIGHTNING, AND CHOPPY
SURF THAT CAN QUICKLY MAKE SWIMMING UNSAFE.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HIGH RIP CURRENT RISK THROUGH WEDNESDAY AFTERNOON FOR PRZ001-002-
005-008-012.
VI...NONE.
AM...NONE.
UPDATE...LIS
PREVIOUS AFD....MIDNIGHT CREW
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