107
FXCA62 TJSJ 151823
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
223 PM AST MON DEC 15 2025
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 132 PM AST MON DEC 15 2025
* AN INCREASE IN MOISTURE WILL CONTINUE TO APPROACH THE ISLANDS
PROMOTING MORE UNSTABLE AND WET CONDITIONS DURING THE FIRST HALF
OF THE WORKWEEK (PARTICULARLY TUESDAY)ACROSS THE U.S. VIRGIN
ISLANDS AND PUERTO RICO.
* SMALL CRAFT ADVISORY NOW IN EFFECT UNTIL 8 PM TONIGHT FOR THE
OFFSHORE ATLANTIC WATERS, WHERE CHOPPY TO ROUGH SEAS EXPECTED
TO CONTINUE.
* A NORTHWESTERLY SWELL IS FORECAST TO ARRIVE BY MIDWEEK,
DETERIORATING MARINE AND COASTAL CONDITIONS THROUGH THE UPCOMING
WEEKEND.
SHORT TERM(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 132 PM AST MON DEC 15 2025
TODAY, MOSTLY CALM CONDITIONS PREVAILED ACROSS PUERTO RICO AND THE
U.S. VIRGIN ISLANDS, WITH MOSTLY CLEAR SKIES DURING THE MORNING
HOURS AND SKIES BECOMING PARTLY CLOUDY DURING THE AFTERNOON AS THE
COMBINATION OF AVAILABLE MOISTURE, DIURNAL HEATING, AND LOCAL
EFFECTS PROMOTED THE GRADUAL DEVELOPMENT OF SOME SHOWERS, MAINLY
OVER THE INTERIOR SECTIONS OF PUERTO RICO. TEMPERATURES ACROSS
URBAN AND COASTAL AREAS REMAINED IN THE UPPER 80S TO LOW 90S,
WHILE MOUNTAIN LOCATIONS STAYED IN THE 70S.
TONIGHT THROUGH WEDNESDAY, WINDS ARE EXPECTED TO REMAIN FROM THE
EAST TO SOUTHEAST AT 5 TO 15 KNOTS AS THE LOCAL AREA REMAINS BETWEEN
A FRONTAL BOUNDARY AND A DISTANT SURFACE HIGH PRESSURE. MODEL
GUIDANCE CONTINUES TO SHOW SIGNIFICANT VARIATIONS IN MOISTURE
CONTENT ON TUESDAY AND WEDNESDAY, WITH THE COLDEST 500 MB
TEMPERATURES OCCURRING TUESDAY AFTERNOON, AROUND −6 TO −7 DEGREES
CELSIUS, WHICH WILL FAVOR THE DEVELOPMENT OF HEAVIER SHOWERS AND
ISOLATED THUNDERSTORMS.
THEREFORE, EXPECTED IMPACTS INCLUDE PONDING OF WATER ON ROADS AND
IN POOR DRAINAGE AREAS EACH DAY ACROSS THE ISLANDS, WITH A HIGHER
RISK OF URBAN AND SMALL STREAM FLOODING ON TUESDAY ACROSS PUERTO
RICO.
LONG TERM(THURSDAY THROUGH NEXT SUNDAY)
ISSUED AT 132 PM AST MON DEC 15 2025
THE FORECAST REMAINS ON TRACK WITH PREVIOUS DISCUSSIONS. A
BUILDING SURFACE HIGH-PRESSURE SYSTEM OVER THE WESTERN ATLANTIC
WILL CONTINUE TO PUSH LINGERING MOISTURE FROM A FRONTAL BOUNDARY
INTO THE LOCAL AREA FROM THURSDAY INTO FRIDAY. THIS WILL INCREASE
THE FREQUENCY OF PASSING SHOWERS ACROSS PUERTO RICO AND THE U.S.
VIRGIN ISLANDS, PARTICULARLY DURING THE MORNING HOURS ACROSS THE
WINDWARD PORTIONS. AS THE SURFACE HIGH CONTINUES TO MOVE OVER THE
ATLANTIC OCEAN, ANOTHER FRONTAL BOUNDARY WILL MOVE EAST OF THE
EASTERN COAST OF THE CONUS, PROMOTING A NORTHEASTERLY WIND FLOW
ACROSS THE AREA. UNDER THIS PATTERN, COOLER TEMPERATURES WILL BE
FELT ACROSS THE REGION DURING THE UPCOMING WEEKEND. BY SUNDAY,
ANOTHER SURFACE HIGH PRESSURE BEHIND THE FRONT IS EXPECTED TO
STRENGTHEN NORTH OF THE LOCAL AREA, BRINGING SLIGHTLY DRIER
CONDITIONS; NONETHELESS, PATCHES OF MOISTURE WILL CONTINUE TO MOVE
INTO THE ISLANDS, PROMOTING SHOWERS FROM TIME TO TIME.
AVIATION
(18Z TAFS)
ISSUED AT 132 PM AST MON DEC 15 2025
MAINLY VFR CONDITIONS ACROSS ALL TAF SITES. E-SE WINDS AROUND 10 TO
15 KTS, WITH HIGHER GUST AND SEA BREEZE VARIATIONS THROUGH
15/22Z, BCMG LIGHT AND VARIABLE BTW 15/22Z TO 16/13Z. SHRA AT OR
IN THE VCTY OF TIST AND TISX THROUGHOUT THE OVERNIGHT PERIOD. VCSH
ALSO POSSIBLE ALONG PR TERMINALS.
MARINE
ISSUED AT 132 PM AST MON DEC 15 2025
MODERATE SOUTHEAST WINDS AND A SUBSIDING LONG-PERIOD NORTHERLY SWELL
WILL RESULT IN CHOPPY SEAS THROUGH TONIGHT, MAINLY ACROSS THE
OFFSHORE ATLANTIC WATERS. A SMALL CRAFT ADVISORY REMAIN IN EFFECT AT
LEAST THROUGH 8 PM TONIGHT ACROSS THE ATLANTIC OFFSHORE WATERS. A
SURFACE HIGH PRESSURE SYSTEM WILL CONTINUE TO BUILD NEAR THE AZORES.
A WEAK COLD FRONT AND ANOTHER SURFACE HIGH PRESSURE SYSTEM WILL MOVE
FROM THE WESTERN ATLANTIC INTO THE CENTRAL ATLANTIC OVER THE NEXT FEW
DAYS. THIS PATTERN WILL PROMOTE MODERATE TO LOCALLY FRESH EAST TO
SOUTHEAST TRADE WINDS ACROSS THE LOCAL WATERS, PARTICULARLY TUESDAY
ONWARDS. ANOTHER LONG-PERIOD NORTHERLY SWELL WILL REACH THE ATLANTIC
WATERS AND LOCAL PASSAGES ON WEDNESDAY WITH SMALL CRAFT ADVISORIES
LIKELY RETURNING.
BEACH FORECAST
ISSUED AT 132 PM AST MON DEC 15 2025
A MODERATE RISK OF RIP CURRENTS WILL CONTINUE ALONG MOST BEACHES
OF THE ISLANDS THROUGH MID-WEEK. THIS MEANS THAT LIFE-THREATENING
RIP CURRENTS ARE POSSIBLE IN THE SURF ZONE, AND BEACHGOERS ARE
ENCOURAGED TO EXERCISE CAUTION. THE MODERATE RISK OF RIP CURRENTS
IS EXPECTED TO PREVAIL ACROSS NORTH-FACING BEACHES OF PUERTO
RICO, CULEBRA, AND THE U.S. VIRGIN ISLANDS, WITH A LOW RISK
ELSEWHERE. REMEMBER THAT EVEN WHEN THE RISK IS LOW, LIFE-
THREATENING RIP CURRENTS CAN STILL OCCUR, ESPECIALLY NEAR GROINS,
JETTIES, REEFS, AND PIERS.
LATE MIDWEEK, BEACH CONDITIONS ARE ANTICIPATED TO DETERIORATE
AGAIN DUE TO INCREASING WINDS AND A NORTHWESTERLY SWELL SPREADING
ACROSS THE LOCAL ATLANTIC WATERS. STAY TUNED TO THE FORECAST! FOR
SPECIFIC LOCATION INFORMATION, PLEASE VISIT WEATHER.GOV/BEACH/SJU.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 8 PM AST THIS EVENING FOR AMZ711.
SHORT TERM...MMC
LONG TERM....GRS
AVIATION...MRR
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