296
FXCA62 TJSJ 131815
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
215 PM AST SAT DEC 13 2025
..NEW SHORT TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 215 PM AST SAT DEC 13 2025
* CHOPPY TO ROUGH SEAS AND LIFE-THREATENING RIP CURRENTS ARE
EXPECTED TO CONTINUE THROUGH THE WEEKEND ACROSS THE ISLANDS.
* INCREASED MOISTURE DUE TO A TROUGH WILL CONTINUE TO REACH THE
ISLANDS FOR THE REST OF TODAY INTO SUNDAY, INCREASING PASSING
SHOWER ACTIVITY. LIMITED AFTERNOON CONVECTION POSSIBLE OVER
NORTHWEST PR.
* FOR THE U.S. VIRGIN ISLANDS, PASSING SHOWERS WILL INCREASE IN
FREQUENCY ONCE AGAIN FOR THE REST OF TODAY THROUGH SUNDAY.
* BREEZY TO LOCALLY WINDY CONDITIONS ARE EXPECTED TO CONTINUE
TOMORROW.
* THE APPROACH OF A FRONTAL SYSTEM AND ITS ASSOCIATED UPPER-LEVEL
TROUGH OVER THE WESTERN ATLANTIC WILL PROMOTE UNSTABLE CONDITIONS
DURING THE FIRST HALF OF THE WORKWEEK.
SHORT TERM(THIS EVENING THROUGH MONDAY)
ISSUED AT 215 PM AST SAT DEC 13 2025
EARLY THIS MORNING, ISOLATED TO SCATTERED SHOWERS MOVED ACROSS
WINDWARD PORTIONS OF THE ISLANDS, FOLLOWED BY A PATCH OF DRIER AIR
THAT RESULTED IN TRANQUIL CONDITIONS THROUGH MIDDAY. AFTERWARD,
MOISTURE CONTENT GRADUALLY INCREASED, BRINGING ADDITIONAL FAST-
MOVING SHOWERS WITH NO SIGNIFICANT IMPACTS. DAYTIME HIGHS REACHED
THE MID TO UPPER 80S, WITH SOME COASTAL STATIONS REPORTING LOW
90S. ACROSS THE HIGHER ELEVATIONS OF PUERTO RICO, TEMPERATURES
REMAINED IN THE 70S TO LOW 80S. AS ANTICIPATED, BREEZY WINDS
PERSISTED, WITH SEVERAL SURFACE STATIONS REPORTING SUSTAINED WINDS
OF 12 TO 20 MPH AND GUSTS BETWEEN 25 AND 30 MPH FROM THE EAST TO
SOUTHEAST.
FOR THE REST OF THE AFTERNOON, A VARIABLE WEATHER PATTERN IS
EXPECTED TO CONTINUE, WITH BREAKS AND PERIODS OF FAST-MOVING
SCATTERED TO NUMEROUS SHOWERS ACROSS THE ISLANDS. THIS ACTIVITY IS
ASSOCIATED WITH A SURGE OF MOISTURE FROM A WEAK TRADE-WIND TROUGH
MOVING THROUGH THE AREA. CONDITIONS ARE EXPECTED TO BECOME WETTER
BY LATE THIS AFTERNOON AND TONIGHT ACROSS THE U.S. VIRGIN
ISLANDS, MOST COASTAL AREAS OF NORTHERN AND SOUTHERN PUERTO RICO,
AND THE EASTERN HALF OF PUERTO RICO AS THE AFOREMENTIONED TROUGH
CROSSES THE LOCAL AREA. RECENT SATELLITE-DERIVED PWAT DATA
INDICATE VALUES NEAR 1.8 TO 2.0 INCHES, WHICH ARE ABOVE NORMAL
BASED ON CLIMATOLOGICAL DATA. AS A RESULT, THERE IS A LIMITED TO
ELEVATED FLOOD RISK TONIGHT ACROSS EASTERN PUERTO RICO AND THE
U.S. VIRGIN ISLANDS AS AN ADVECTIVE PATTERN BECOMES ESTABLISHED.
PONDING OF WATER ON ROADS AND IN POORLY DRAINED AREAS, AS WELL AS
URBAN, ROADS, SMALL-STREAM, AND WASH FLOODING, ARE POSSIBLE.
BY SUNDAY, PWAT VALUES ARE EXPECTED TO DROP NOTABLY BELOW NORMAL
AS A DRIER AND MORE STABLE AIR MASS MOVES IN FROM THE EAST. THIS
WILL ALLOW FOR A MOSTLY SUNNY DAY WITH ONLY ISOLATED SHOWERS
(0–20%), ALTHOUGH BREEZY WINDS ARE EXPECTED TO PERSIST,
PARTICULARLY ACROSS COASTAL AREAS. BY MONDAY, LIGHTER WINDS ARE
FORECAST, AND MOISTURE CONTENT WILL GRADUALLY INCREASE AGAIN LATE
SUNDAY NIGHT INTO MONDAY. SCATTERED SHOWERS (30 TO 50%) ARE
FORECAST TO INCREASE AGAIN AS THE SYNOPTIC SETUP, AFFECTED BY A
PRE-FRONTAL TROUGH, STARTS TO BECOME MORE FAVORABLE FOR RAINFALL.
LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 345 AM AST SAT DEC 13 2025
THE APPROACH OF A FRONTAL SYSTEM AND ITS ASSOCIATED UPPER-LEVEL
TROUGH OVER THE WESTERN ATLANTIC WILL PROMOTE UNSTABLE CONDITIONS
DURING THE FIRST HALF OF THE LONG TERM PERIOD. NORMAL TO SLIGHTLY
ABOVE-NORMAL PRECIPITABLE WATER CONTENT (PWAT) OF 1.75 TO 1.90
INCHES WILL ENHANCE THE POTENTIAL FOR SHOWER DEVELOPMENT ACROSS THE
REGION. SHOWERS ARE MOST LIKELY OVER PORTIONS OF EASTERN PUERTO RICO
AND THE U.S. VIRGIN ISLANDS DURING THE OVERNIGHT AND MORNING HOURS,
FOLLOWED BY AFTERNOON SHOWERS OVER PORTIONS OF CENTRAL AND WESTERN
PUERTO RICO. DURING THIS PERIOD, THE 500 MB TEMPERATURES ARE
EXPECTED TO DROP INTO THE -6C TO -7C RANGE, MEANING THE POTENTIAL
FOR AFTERNOON THUNDERSTORMS, PARTICULARLY ACROSS WESTERN PUERTO
RICO, CANNOT BE RULED OUT.
AT THE SURFACE, A STRONG HIGH-PRESSURE SYSTEM LOCATED OVER THE
CENTRAL ATLANTIC WILL MAINTAIN AN EAST-SOUTHEASTERLY WIND FLOW
ACROSS THE AREA, PROMOTING SLIGHTLY HIGHER THAN NORMAL TEMPERATURES
THROUGHOUT THE WEEK. HOWEVER, BY THE SECOND HALF OF THE LONG-TERM
PERIOD, ANOTHER HIGH-PRESSURE SYSTEM IS EXPECTED TO BUILD OVER THE
WESTERN ATLANTIC BEHIND THE FRONTAL SYSTEM. BY THEN, WINDS ARE
EXPECTED TO SHIFT FROM THE NORTHEAST, LEADING TO COOLER TEMPERATURES
INTO THE NORTHEASTERN CARIBBEAN REGION.
AVIATION
(18Z TAFS)
ISSUED AT 215 PM AST SAT DEC 13 2025
VFR CONDITIONS FOR THE TERMINALS. E-SE WINDS AT 13-20 KTS, WITH
GUSTS UP TO 23-30 KTS THROUGH 13/23Z, DECREASING AFTER. AN INCREASE
IN VCSH/-SHRA (DUE TO A WEAK SURFACE TROUGH) IS FORECAST DURING THE
AFTERNOON TO OVERNIGHT HOURS, THESE CAN PROMOTE TEMPO MVFR
CONDITIONS TO BRIEF IFR CONDITIONS OVER EASTERN TERMINALS. ISOL
VCTS/-TSRA ALSO POSSIBLE, THROUGH 14/07Z. WINDS WILL INCREASE AGAIN
AFTER AROUND 14/13-14Z TO 12 TO 18 KT FROM THE E-SE, WITH HIGHER
GUSTS AND SEA BREEZE VARIATIONS.
MARINE
ISSUED AT 215 PM AST SAT DEC 13 2025
A SURFACE HIGH-PRESSURE SYSTEM WILL CONTINUE TO BUILD NEAR THE
AZORES THROUGH THE WEEKEND, PROMOTING MODERATE TO FRESH EAST TO
SOUTHEAST WINDS ACROSS THE LOCAL WATERS. INCREASING WINDS AND A
FADING LONG-PERIOD NORTHERLY SWELL WILL RESULT IN CHOPPY TO ROUGH
SEAS, MAINLY ACROSS THE ATLANTIC WATERS. SMALL CRAFT ADVISORIES
REMAIN IN EFFECT AT LEAST THROUGH SUNDAY AFTERNOON ACROSS THE
OFFSHORE ATLANTIC WATERS. A COLD FRONT AND ANOTHER SURFACE HIGH-
PRESSURE SYSTEM WILL MOVE FROM THE WESTERN ATLANTIC INTO THE
CENTRAL ATLANTIC EARLY NEXT WEEK, WEAKENING THE PRESSURE GRADIENT
AND ALLOWING FOR GENTLE TO MODERATE WINDS THROUGH TUESDAY. BY
MIDWEEK, INCREASING WINDS AND A NORTHWESTERLY SWELL WILL
DETERIORATE MARINE CONDITIONS ONCE AGAIN.
BEACH FORECAST
ISSUED AT 215 PM AST SAT DEC 13 2025
A FADING, LONG-PERIOD NORTHERLY SWELL WILL CREATE LIFE-THREATENING
RIP CURRENTS ALONG THE NORTH AND EAST FACING BEACHES OF THE
ISLANDS, WHERE A RIP CURRENT STATEMENT REMAINS IN EFFECT AT LEAST
THROUGH SUNDAY MORNING. BEACHGOERS ARE URGED TO AVOID SWIMMING
UNDER THESE CONDITIONS. THE WEST AND SOUTH-FACING BEACHES OF THE
ISLANDS WILL HAVE A MODERATE RISK OF RIP CURRENTS TONIGHT. BY
SUNDAY AND EARLY NEXT WEEK, A LOW TO MODERATE RISK OF RIP CURRENTS
IS EXPECTED TO DOMINATE, WITH BEACH CONDITIONS DETERIORATING
AGAIN BY MIDWEEK AS A NORTHWESTERLY SWELL SPREADS ACROSS THE LOCAL
ATLANTIC WATERS. FOR SPECIFIC LOCATION INFORMATION, PLEASE VISIT
WEATHER.GOV/BEACH/SJU.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HIGH RIP CURRENT RISK THROUGH LATE TONIGHT FOR PRZ001-002-005-
008.
HIGH RIP CURRENT RISK UNTIL 6 PM AST THIS EVENING FOR PRZ012.
VI...HIGH RIP CURRENT RISK UNTIL 6 PM AST THIS EVENING FOR VIZ002.
AM...SMALL CRAFT ADVISORY UNTIL 5 PM AST SUNDAY FOR AMZ711.
SHORT TERM...YZR
LONG TERM....GRS
AVIATION...MRR
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page