619
FXCA62 TJSJ 141837
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
237 PM AST SUN DEC 14 2025
..NEW SHORT TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 237 PM AST SUN DEC 14 2025
* CHOPPY TO ROUGH SEAS ARE EXPECTED TO CONTINUE ACROSS THE
OFFSHORE ATLANTIC WATERS THROUGH AT LEAST EARLY MONDAY MORNING.
* UP TO A MODERATE RISK OF RIP CURRENTS TONIGHT, WITH A
NORTHWESTERLY SWELL FORECAST TO ARRIVE BY MIDWEEK AND
DETERIORATE CONDITIONS.
* A DRY AND STABLE AIR MASS WILL CONTINUE TO MOVE OVER PUERTO RICO
AND THE U.S. VIRGIN ISLANDS THIS AFTERNOON AND EARLY TONIGHT,
LIMITING SHOWER ACTIVITY.
* THE APPROACH OF A FRONTAL SYSTEM AND ITS ASSOCIATED UPPER-LEVEL
TROUGH OVER THE WESTERN ATLANTIC WILL PROMOTE MORE UNSTABLE AND
WET CONDITIONS DURING THE FIRST HALF OF THE WORKWEEK.
SHORT TERM(THIS EVENING THROUGH TUESDAY)
ISSUED AT 237 PM AST SUN DEC 14 2025
FAIR WEATHER PREVAILED TODAY, AS A DRY AND STABLE AIR MASS REMAINED
OVER THE ISLANDS. CURRENT SATELLITE DERIVED PRECIPITABLE WATER
(PWAT) VALUES INDICATE BETWEEN 1 TO 1.3 INCHES, BELOW SEASONAL
VALUES. ESE STEERING FLOW HELPED PROMOTE NORMAL TO SLIGHTLY ABOVE
NORMAL 925 MB TEMPERATURES. HIGHS REACHED THE MID TO UPPER 80S, WITH
SOME STATIONS REPORTING HIGHS IN THE LOW 90S, ACROSS COASTAL AND
URBAN AREAS. HIGHER ELEVATIONS OF PUERTO RICO SAW MAXIMUM
TEMPERATURES FROM THE 70S TO AROUND 80. SEVERAL COASTAL OFFICIAL AND
UNOFFICIAL STATIONS REPORTED SUSTAINED WINDS UP TO 13 TO 18 MPH WITH
HIGHER GUSTS AROUND 19 TO 28 MPH.
ONLY LIMITED SHOWER DEVELOPMENT IS POSSIBLE THIS AFTERNOON AND
EARLY TONIGHT OVER THE ISLANDS. PATCHY FOG WILL ONCE AGAIN RETURN
OVER AREAS OF THE INTERIOR. THE SURFACE HIGH OVER THE CENTRAL TO
WESTERN ATLANTIC, PROMOTING THE ABOVE MENTIONED STEERING FLOW,
WILL CONTINUE GRADUALLY MOVING EASTWARD AS A FRONTAL LOW EXITS THE
EASTERN U.S. ANOTHER HIGH WILL THEN ENTER THE WESTERN ATLANTIC
TOMORROW, LEAVING THE ISLANDS BETWEEN THE TWO HIGHS. THIS WILL
CONTINUE TO RESULT IN ESE STEERING FLOW, RESULTING IN PATCHES OF
MOISTURE AND WEAK SURFACE TROUGHS HEADING TOWARDS THE ISLANDS
TOMORROW AND TUESDAY.
PWAT VALUES ARE FORECAST AT SEASONAL TO ABOVE SEASONAL LEVELS
EARLY IN THE WORKWEEK AS MOISTURE CONTINUES TO BE STEERED TOWARDS
THE ISLANDS, A COLD FRONT AND RELATED TROUGH ARE NORTH OF THE
REGION, AND AN INDUCED PRE-FRONTAL TROUGH IS NEAR THE AREA.
CURRENT MODEL GUIDANCE HAS PWAT INCREASING LATE TONIGHT INTO
TOMORROW, HELPING PROMOTE A WETTER PATTERN AND SHOWER ACTIVITY
OVER THE EASTERN REGION MAINLY DURING THE MORNING AND OVERNIGHT
HOURS AND, DURING THE AFTERNOONS, WESTERN PR WITH A SLIGHT CHANCE
OF T-STORM DEVELOPMENT. 925 MB WIND SPEEDS WILL CONTINUE
DECREASING LATER TODAY AND TONIGHT BEFORE GRADUALLY INCREASING
TOMORROW ONWARDS, IN GENERAL THEY ARE FORECAST TO BE LIGHTER AND AT
MORE SEASONAL SPEEDS TO START THE WORKWEEK. 925 MB TEMPERATURES
ARE FORECAST AT SEASONAL TO ABOVE SEASONAL VALUES DUE TO THE ESE
STEERING FLOW.
LONG TERM(WEDNESDAY THROUGH NEXT SATURDAY)
ISSUED AT 403 AM AST SUN DEC 14 2025
THE INHERITED FORECAST REMAINS ON TRACK. INSTABILITY IS EXPECTED
TO ARRIVE IN THE AREA ON WEDNESDAY, DRIVEN BY AN UPPER-LEVEL
TROUGH POSITIONED ALONG A FRONTAL BOUNDARY NORTH OF THE REGION.
AT THE SURFACE, A BUILDING HIGH-PRESSURE SYSTEM OVER THE WESTERN
ATLANTIC WILL BEGIN TO PUSH MOISTURE ASSOCIATED WITH THIS FRONT
INTO THE LOCAL AREA, PROMOTING WETTER CONDITIONS BY THE LATTER
PART OF THE WEEK. AS THIS SURFACE HIGH STRENGTHENS, WINDS WILL
SHIFT TO THE NORTHEAST, PUSHING SLIGHTLY COOLER AIR INTO THE AREA.
UNDER THIS PATTERN, FREQUENT PASSING SHOWERS ARE EXPECTED DURING
THE MORNING HOURS ACROSS PORTIONS OF EASTERN PUERTO RICO AND THE
U.S. VIRGIN ISLANDS, FOLLOWED BY AFTERNOON SHOWERS OVER PORTIONS
OF CENTRAL AND WESTERN PUERTO RICO. DURING THIS PERIOD,
PRECIPITABLE WATER CONTENT VALUES ARE EXPECTED TO RANGE FROM 1.6
TO 1.8 INCHES, SUGGESTING NORMAL TO NEAR-ABOVE-NORMAL VALUES FOR
THE SEASON. AT THE 500 MB LEVEL, TEMPERATURES ARE EXPECTED TO
REMAIN AROUND -6C; HOWEVER, ISOLATED THUNDERSTORMS CANNOT BE RULED
OUT, PARTICULARLY WITH THE AFTERNOON ACTIVITY OVER WESTERN PUERTO
RICO. FURTHERMORE, THE INCREASING PRESSURE GRADIENT FORCE DRIVEN
BY THE STRENGTHENING HIGH PRESSURE WILL RESULT IN BREEZY
CONDITIONS DURING THE LATTER HALF OF THE WEEK, WITH WIND SPEEDS
SUSTAINED BETWEEN 15 TO 20 KNOTS.
AVIATION
(18Z TAFS)
ISSUED AT 237 PM AST SUN DEC 14 2025
VFR CONDITIONS ARE EXPECTED FOR THE REST OF TODAY ACROSS ALL TAF
SITES. WINDS FROM THE E TO SE AROUND 10 TO 15 KTS THRU 14/22Z, THEN
BELOW 7 KTS THRU 15/14Z ACROSS PR TAF SITES. VCSH AND PERIODS OF -RA
ACROSS TIST AND TISX DURING THE OVERNIGHT PERIOD INTO THE MORNING
HOURS, THEN INTO TJSJ, TJPS AND TJBQ AROUND 15/15-17Z ONWARD. EXPECT
INTERMITTENT PERIODS OF MVFR CONDITIONS DUE TO CIGS AND REDUCED VIS
AT TIMES. E-SE WINDS FORM 15/14Z AT AROUND 8 TO 12 KTS.
MARINE
ISSUED AT 237 PM AST SUN DEC 14 2025
A SURFACE HIGH-PRESSURE SYSTEM ACROSS THE EASTERN INTO CENTRAL
ATLANTIC WILL CONTINUE TO PROMOTE MODERATE TO LOCALLY FRESH EAST TO
SOUTHEAST WINDS ACROSS THE LOCAL WATERS TONIGHT. WIND-DRIVEN SEAS
ARE PROMOTING HAZARDOUS MARINE CONDITIONS FOR SMALL CRAFT OPERATORS
ACROSS THE OFFSHORE ATLANTIC WATERS, WHERE A SMALL CRAFT ADVISORY
REMAIN IN EFFECT AT LEAST THROUGH MONDAY MORNING. A COLD FRONT AND
ANOTHER SURFACE HIGH-PRESSURE SYSTEM WILL MOVE FROM THE WESTERN
ATLANTIC INTO THE CENTRAL ATLANTIC OVER THE NEXT FEW DAYS, WEAKENING
THE PRESSURE GRADIENT AND ALLOWING FOR GENTLE TO MODERATE WINDS
MONDAY AND TUESDAY. BY MIDWEEK, INCREASING WINDS AND A NORTHWESTERLY
SWELL WILL LIKELY DETERIORATE MARINE CONDITIONS ONCE AGAIN.
BEACH FORECAST
ISSUED AT 237 PM AST SUN DEC 14 2025
TONIGHT, THERE IS A MODERATE RISK OF RIP CURRENTS ALONG MOST BEACHES
OF THE ISLANDS. THIS MEANS THAT LIFE-THREATENING RIP CURRENTS ARE
POSSIBLE IN THE SURF ZONE, AND BEACHGOERS ARE ENCOURAGED TO EXERCISE
CAUTION. EARLY THIS WEEK, A 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.
BY 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 6 AM AST MONDAY FOR AMZ711.
MRR/YZR
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