374
FXCA62 TJSJ 301827
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
227 PM AST THU OCT 30 2025
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 200 PM AST THU OCT 30 2025
* PUERTO RICO CAN EXPECT A LIMITED TO ELEVATED FLOODING RISKS AND
ISOLATED LIGHTNING RISK FRIDAY INTO SATURDAY.
* THE U.S. VIRGIN ISLANDS SHOULD EXPERIENCE PERIODS OF PASSING
SHOWERS PARTICULARLY DURING THE OVERNIGHT INTO THE EARLY MORNING
HOURS THROUGH AT LEAST SATURDAY.
* THE NORTH-FACING BEACHES IN PR AND THE US VIRGIN ISLANDS WILL
REMAIN WITH A MODERATE RISK OF RIP CURRENTS THROUGH THE WEEKEND.
* AN IMPROVEMENT IN WEATHER CONDITIONS IS FORECAST BY SUNDAY.
SHORT TERM (THIS EVENING THROUGH SATURDAY)
ISSUED AT 200 PM AST THU OCT 30 2025
MOSTLY CALM WEATHER CONDITIONS PREVAILED ACROSS PUERTO RICO AND THE
U.S. VIRGIN ISLANDS TODAY. TEMPERATURES ALONG THE COASTAL AND URBAN
AREAS STAYED IN THE UPPER 80S TO LOW AND MID-90S, WITH THE HIGHEST
READINGS OBSERVED ACROSS THE NORTH-CENTRAL SECTIONS OF PUERTO RICO.
MEANWHILE, THE MOUNTAINOUS AND MORE RURAL AREAS EXPERIENCED
TEMPERATURES IN THE UPPER 70S TO LOW 80S. BESIDES TEMPERATURES, HEAT
INDICES FROM NON-OFFICIAL WEATHER STATIONS RANGED BETWEEN 98 AND 108
DEGREES FAHRENHEIT ACROSS THE LOWER ELEVATIONS AND IN THE 80S ACROSS
THE HIGHER TERRAINS. IT IS ESSENTIAL TO REMEMBER THAT THE HEAT INDEX
REPRESENTS THE ACTUAL TEMPERATURE SENSATION EXPERIENCED BY THE HUMAN
BODY WHEN TEMPERATURE AND HUMIDITY ARE COMBINED. WINDS REMAINED
GENERALLY FROM THE SOUTHEAST AT 10 TO 15 MPH, WITH SLIGHTLY HIGHER
OCCASIONAL GUSTS. OVERALL, FAIR AND HOT WEATHER DOMINATED THE REGION
TODAY, WITH LIMITED SHOWER ACTIVITY ACROSS SOUTHERN PR AND MOSTLY
CLEAR SKIES ELSEWHERE.
TONIGHT, MAINLY FAIR WEATHER CONDITIONS ARE EXPECTED TO CONTINUE
ACROSS THE ISLANDS. HOWEVER, BRIEF PASSING SHOWERS MAY OCCASIONALLY
MOVE ACROSS THE U.S. VIRGIN ISLANDS AND THE COASTAL AND EASTERN
SECTIONS OF PUERTO RICO THROUGH THE EARLY MORNING HOURS. WINDS WILL
REMAIN FROM THE SOUTHEAST AROUND 10 TO 15 MPH AS HURRICANE MELISSA
CONTINUES TO MOVE INTO THE NORTHWESTERN ATLANTIC. THE OVERNIGHT
TEMPERATURES WILL RANGE FROM THE UPPER 70S TO THE LOW 80S ACROSS
COASTAL AREAS AND FROM THE UPPER 60S TO MID-70S IN THE HIGHER
ELEVATIONS.
ON FRIDAY, WINDS WILL GRADUALLY BECOME MORE EASTERLY AS A TROPICAL
WAVE APPROACHES THE LESSER ANTILLES AND CONTINUES ITS MOVEMENT SOUTH
OF PR AND THE USVI, SUPPORTING A MORE FAVORABLE ENVIRONMENT FOR
SHOWER AND THUNDERSTORM DEVELOPMENT, PARTICULARLY DURING THE
AFTERNOON HOURS, COMBINED WITH LOCAL EFFECTS. THE LATEST MODEL
GUIDANCE SUGGESTS PRECIPITABLE WATER VALUES EXCEEDING 2.0 INCHES
WILL PROMOTE MORE FREQUENT AND WIDESPREAD CONVECTION. SHOWERS ARE
EXPECTED TO FAVOR WINDWARD AND EASTERN AREAS DURING THE EARLY
MORNING AND NIGHTTIME HOURS, THEN SHIFT TOWARD THE INTERIOR AND
WESTERN SECTIONS EACH AFTERNOON. AS A RESULT, FLOODING AND LIGHTNING
HAZARDS ARE EXPECTED TO INCREASE, WITH FLOODING RISKS RISING TO
ELEVATED LEVELS AND LIGHTNING TO LIMITED OR MODERATE. WIND RISKS MAY
ALSO INCREASE LATE FRIDAY AS THE SURFACE FLOW BACKS TO THE EAST-
SOUTHEAST AND STRENGTHENS.
THESE WEATHER CONDITIONS WILL REMAIN THROUGH SATURDAY. SOME
GRADUAL DRYING IS FORECAST BY LATE SATURDAY AS A DRIER AIR MASS
FROM THE EAST. HIGH TEMPERATURES WILL REMAIN IN THE UPPER 80S TO
MID-90S ALONG COASTAL AND URBAN AREAS AND IN THE UPPER 70S TO LOW
80S ACROSS THE MOUNTAINS. HEAT INDICES WILL CONTINUE TO REACH
DANGEROUS LEVELS, ESPECIALLY IN AREAS WITH PROLONGED SUNSHINE.
LONG TERM (SUNDAY THROUGH NEXT WEDNESDAY)
ISSUED AT 200 PM AST THU OCT 30 2025
FROM PREVIOUS DISCUSSION
A MID- TO UPPER-LEVEL RIDGE OF HIGH PRESSURE IS LIKELY TO REMAIN
IN PLACE THROUGH MUCH OF THE LONG-TERM FORECAST, BUT BY MONDAY OR
TUESDAY, A WEAK UPPER-LEVEL LOW-PRESSURE SYSTEM WILL MOVE ACROSS
THE CARIBBEAN SEA, WEAKENING ATMOSPHERIC STABILITY. CONFIDENCE IN
THIS OUTCOME REMAINS MEDIUM (30% - 50%). DESPITE THIS UPPER-LEVEL
FEATURE, A STRONG RIDGE NEAR THE 700 MB LEVEL IS EXPECTED TO
PERSIST ACROSS THE NORTHEAST CARIBBEAN, MAINTAINING GENERALLY
STABLE CONDITIONS ALOFT.
AT THE SURFACE, HIGH PRESSURE BUILDING OVER THE WESTERN ATLANTIC
AND EXPANDING INTO THE CENTRAL ATLANTIC WILL LIKELY STRENGTHEN THE
LOCAL PRESSURE GRADIENT, RESULTING IN BREEZY EAST TO EAST-
SOUTHEAST WINDS ACROSS THE ISLANDS. THIS PATTERN SHOULD TRANSPORT
PATCHES OF LOW-LEVEL MOISTURE, LEADING TO A VARIABLE MIX OF MOSTLY
CLEAR SKIES AND OCCASIONAL PASSING SHOWERS. THERE IS A MODERATE
CHANCE (30-50%) THAT THIS SCENARIO WILL OCCUR ACROSS THE ISLANDS
EACH DAY.
WHILE ISOLATED AFTERNOON CONVECTION CANNOT BE RULED OUT (20%-30%
CHANCE), MAINLY DUE TO LOCAL TOPOGRAPHY, SEA-BREEZE INTERACTIONS,
AND DIURNAL HEATING, ONLY A SLIGHT CHANCE (LESS THAN 30%) EXISTS
FOR THUNDERSTORM DEVELOPMENT GIVEN THE PERSISTENT TRADE-WIND
INVERSION AND DRY AIR ALOFT. THE MOST FAVORABLE WINDOW FOR
AFTERNOON SHOWERS OR AN ISOLATED THUNDERSTORM APPEARS TO BE MONDAY
INTO TUESDAY (WITH A 30-50% CHANCE), ALTHOUGH OVERALL CONFIDENCE
IN SIGNIFICANT CONVECTIVE ACTIVITY REMAINS LOW.
AVIATION...
(18Z TAFS)
ISSUED AT 200 PM AST THU OCT 30 2025
MAINLY VFR THRU PRD WITH QUIET WX AND VERY LTD CONVECTIVE
DVLPMNT. NO SHRA/TSRA EXPECTED THRU TONIGHT, EXCEPT BRIEF -SHRA
PSBL NR TJBQ THRU 30/22Z. MVFR CONDS UNLIKELY AT MOST TAF SITES,
BUT BRIEF MVFR PSBL AT TJSJ/USVI TERMINALS AFT 31/13Z DUE TO
PASSING SHRA. SFC WNDS S–SE 10–15KT, OCNL G20KT THRU AFTN, BCMG
LGT/VRB AFT 30/23Z, THEN INCR TO 10–15KT FM E–ESE AND GUSTY AFT
31/13Z. FEW–SCT CLDS XPCD THRU PRD.
MARINE
ISSUED AT 200 PM AST THU OCT 30 2025
THE REGION WILL CONTINUE UNDER A SOUTHEASTERLY WIND FLOW THROUGH
TONIGHT, AS MELISSA MOVES INTO THE WESTERN ATLANTIC. THEN, A
FRONTAL BOUNDARY WILL APPROACH THE REGION FROM THE WEST,
INTERACTING WITH A SURFACE HIGH PRESSURE ANCHORED ACROSS THE
CENTRAL ATLANTIC AROUND FRIDAY, PROMOTING THE RETURN OF A MODERATE
TO LOCALLY FRESH EASTERLY WIND FLOW. A TROPICAL WAVE WILL MOVE
NEAR THE NORTHEAST CARIBBEAN AND THE LOCAL WATERS AROUND SATURDAY,
INCREASING THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS.
BEACH FORECAST
ISSUED AT 200 PM AST THU OCT 30 2025
BEACHGOERS CAN EXPECT A MODERATE RISK OF RIP CURRENTS ALONG THE
NORTH AND EAST-FACING BEACHES IN PR AND THE USVI. THE MODERATE
RISK WILL PERSIST THROUGH THE WEEKEND AND EARLY NEXT WEEK. OVER
THE WEEKEND, THE MODERATE RISK WILL EXPAND TO MOST LOCAL BEACHES
AS WINDS STRENGTHEN AHEAD OF AN APPROACHING TROPICAL WAVE. ADDITIONALLY,
THE POTENTIAL FOR THUNDERSTORMS WILL INCREASE ON SATURDAY DUE TO
THE ARRIVAL OF A TROPICAL WAVE. BEACHGOERS SHOULD REMAIN CAUTIOUS
AND FOLLOW GUIDANCE FROM LOCAL AUTHORITIES AND LIFEGUARDS.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HEAT ADVISORY UNTIL 5 PM AST THIS AFTERNOON FOR PRZ001>005-007-
008-010>013.
VI...HEAT ADVISORY UNTIL 5 PM AST THIS AFTERNOON FOR VIZ001-002.
AM...NONE.
SHORT TERM...MMC/ICP
LONG TERM...MIDNIGHT CREW
AVIATION...ICP
MARINE/BEACH FORECAST...MMC
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