885
FXCA62 TJSJ 171841
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
241 PM AST WED DEC 17 2025
..NEW SHORT TERM, LONG TERM, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 218 PM AST WED DEC 17 2025
* PULSES OF A NORTHERLY SWELL WILL BRING DANGEROUS MARINE AND
BEACH CONDITIONS THROUGH THURSDAY MORNING, INCLUDING HIGH SURF,
LOCALIZED COASTAL FLOODING, AND LIFE-THREATENING RIP CURRENTS
ACROSS NORTH-FACING BEACHES OF PUERTO RICO AND THE U.S. VIRGIN
ISLANDS. AFTER THURSDAY MORNING, HAZARDOUS SEAS AND DANGEROUS
RIP CURRENTS WILL CONTINUE INTO EARLY NEXT WEEK, MAINLY DUE TO
PERSISTENT MODERATE TO FRESH WINDS.
* MODERATE TO FRESH NON-THUNDERSTORM WINDS MAY AFFECT EXPOSED AND
ELEVATED AREAS OF PUERTO RICO AND THE U.S. VIRGIN ISLANDS,
CREATING LOCALLY WINDY CONDITIONS AT TIMES, ESPECIALLY ALONG
EXPOSED COASTLINES.
* THUNDERSTORM AND HEAVIER RAINFALL IMPACTS ARE MAINLY EXPECTED
TODAY, WITH PASSING SHOWERS AND ISOLATED STORMS CAPABLE OF
PRODUCING BRIEF HEAVY RAIN, LIGHTNING, GUSTY WINDS, AND
LOCALIZED MINOR FLOODING. THESE RISKS DECREASE TONIGHT, BUT MAY
RETURN NEXT WEEK AS A STRONGER WEATHER SYSTEM APPROACHES.
SHORT TERM(THIS EVENING THROUGH FRIDAY)
ISSUED AT 218 PM AST WED DEC 17 2025
AN ABOVE-NORMAL MOISTURE PATCH MOVED ACROSS THE REGION, PRODUCING
SCATTERED TO LOCALLY NUMEROUS SHOWERS WITH PERIODS OF MODERATE TO
LOCALLY HEAVY RAINFALL. SINCE MIDNIGHT, RAINFALL TOTALS PEAKED
NEAR ONE INCH ACROSS PORTIONS OF SOUTHEASTERN PUERTO RICO, WHILE
AMOUNTS ACROSS THE U.S. VIRGIN ISLANDS GENERALLY REMAINED BELOW A
QUARTER OF AN INCH. SKIES WERE MOSTLY CLOUDY, WITH CLOUDS AND
SHOWERS SPREADING WESTWARD INTO THE INTERIOR AND WESTERN PUERTO
RICO. TEMPERATURES RANGED FROM THE LOWER 60S ACROSS HIGHER
ELEVATIONS OF PUERTO RICO TO NEAR 90 DEGREES IN ISOLATED AREAS OF
WESTERN PUERTO RICO AND SAINT CROIX. WINDS WERE GENERALLY EASTERLY
AT 12 TO 18 MPH, WITH OCCASIONAL GUSTS NEAR SHOWERS AND LOCAL SEA
BREEZE INFLUENCES.
SHOWERS WILL CONTINUE THROUGH THE REST OF TODAY, WITH A FEW
ISOLATED THUNDERSTORMS POSSIBLE THIS AFTERNOON. WHILE WIDESPREAD
SEVERE WEATHER IS NOT EXPECTED, SOME SHOWERS MAY PRODUCE FREQUENT
LIGHTNING, GUSTY WINDS, AND BRIEF HEAVY RAINFALL, LEADING TO
LOCALIZED PONDING OF WATER AND REDUCED VISIBILITY. WINDS WILL
GRADUALLY INCREASE AS HIGH PRESSURE BUILDS OVER THE NORTH
ATLANTIC, REMAINING LIGHT AND VARIABLE INLAND AND STRONGEST ACROSS
EXPOSED COASTAL AREAS. AS DRIER AIR MOVES IN THIS EVENING, SHOWER
COVERAGE WILL DECREASE AND THE THREAT FOR LIGHTNING AND HEAVY
RAINFALL WILL DIMINISH. OVERNIGHT LOW TEMPERATURES WILL RANGE FROM
THE UPPER 60S TO LOWER 70S ACROSS COASTAL AND URBAN AREAS, AND
THE MID-60S ACROSS THE INTERIOR AND HIGHER ELEVATIONS.
FROM THURSDAY THROUGH FRIDAY, WEATHER CONDITIONS WILL BECOME MORE
STABLE AS A MID-LEVEL RIDGE EXPANDS OVER THE REGION, LIMITING
SUSTAINED SHOWER AND THUNDERSTORM DEVELOPMENT. A BRIEF INCREASE IN
MOISTURE IS POSSIBLE THURSDAY NIGHT, BUT OVERALL MOISTURE LEVELS
WILL REMAIN NEAR NORMAL, WITH INCREASING MID-LEVEL DRYING LATE
FRIDAY INTO EARLY SATURDAY. SHOWER ACTIVITY WILL BE MAINLY TRADE-
WIND DRIVEN, FAVORING OVERNIGHT AND EARLY MORNING HOURS ACROSS
WINDWARD AREAS, WITH ONLY LIMITED AFTERNOON ACTIVITY OVER INTERIOR
AND WESTERN PUERTO RICO. WINDS WILL STRENGTHEN FROM THURSDAY
AFTERNOON INTO THURSDAY NIGHT, BECOMING MODERATE TO LOCALLY
BREEZY, THEN EASING ON FRIDAY. RAINFALL IMPACTS SHOULD REMAIN
MINOR AND SHORT-LIVED, WITH LITTLE TO NO RISK OF EXCESSIVE
RAINFALL, FLOODING, OR THUNDERSTORMS THROUGH 10Z SATURDAY.
LONG TERM(SATURDAY THROUGH NEXT TUESDAY)
ISSUED AT 429 AM AST WED DEC 17 2025
A MID-TO-UPPER-LEVEL RIDGE WILL DOMINATE LOCAL WEATHER FOR THE FIRST
HALF OF THE PERIOD, MAINTAINING STABLE CONDITIONS ALOFT. DURING THIS
TIME, PRECIPITABLE WATER (PWAT) VALUES WILL REMAIN BELOW THE
SEASONAL CLIMATOLOGICAL VALUES, RANGING FROM 1.2 TO 1.5 INCHES. AT
THE SURFACE, PATCHES OF LOW-LEVEL MOISTURE WILL CONTINUE TO DRIFT
INTO THE AREA, BRINGING PASSING SHOWERS TO WINDWARD SECTIONS OF THE
ISLANDS. RAINFALL ACCUMULATIONS WILL STAY LIMITED, THOUGH LOCALIZED
AFTERNOON SHOWERS ARE POSSIBLE ACROSS WESTERN PUERTO RICO. OVERALL
IMPACTS ARE EXPECTED TO REMAIN MINIMAL.
TRANSITIONING INTO THE SECOND HALF OF THE PERIOD AND THROUGH
CHRISTMAS EVE, A WETTER PATTERN WILL EVOLVE. THE MID-LEVEL RIDGE
WILL ERODE AS A POLAR TROUGH, EXITING THE EASTERN U.S. COAST,
APPROACHES FROM THE NORTHWEST. THIS WILL INCREASE INSTABILITY, WITH
500MB TEMPERATURES DROPPING TO BETWEEN -6 AND -8°C. AT THE SURFACE,
AN ASSOCIATED FRONTAL BOUNDARY IS FORECAST TO APPROACH LATE TUESDAY
INTO WEDNESDAY. DURING THIS PERIOD MOISTURE WILL INCREASE, WITH PWAT
VALUES REACHING 1.5 TO 1.75 INCHES. THIS COMBINATION OF COOLING
ALOFT AND INCREASED MOISTURE SUGGESTS AN UNSETTLED PATTERN FOR THE
CHRISTMAS HOLIDAY, POTENTIALLY BRINGING ISOLATED THUNDERSTORMS AND
LOCALLY HEAVY RAINFALL THAT COULD INCREASE THE RISK OF FLOODING IN
PRONE AREAS STARTING LATE TUESDAY OR WEDNESDAY.
MARINE
ISSUED AT 218 PM AST WED DEC 17 2025
MODERATE TO LOCALLY FRESH EAST-SOUTHEAST WINDS WILL CONTINUE
ACROSS THE LOCAL WATERS TODAY. COMBINED WITH PULSES OF A NORTHERLY
SWELL, THESE CONDITIONS WILL MAINTAIN HAZARDOUS MARINE CONDITIONS
FOR SMALL CRAFT, ESPECIALLY ACROSS THE ATLANTIC WATERS AND
CARIBBEAN PASSAGES. AS A RESULT, A SMALL CRAFT ADVISORY REMAINS IN
EFFECT THROUGH AT LEAST THURSDAY MORNING. WINDS WILL THEN INCREASE
AND SHIFT TO THE EAST TO EAST-NORTHEAST AS A BROAD SURFACE HIGH
BUILDS OVER THE NORTH ATLANTIC, PRODUCING A MODERATE TO FRESH
BREEZE THAT WILL MAINTAIN HAZARDOUS MARINE CONDITIONS THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK.
BEACH FORECAST
ISSUED AT 218 PM AST WED DEC 17 2025
LIFE-THREATENING BEACH CONDITIONS WILL CONTINUE DUE TO REPEATED
PULSES OF A NORTHERLY SWELL. HIGH SURF AND COASTAL FLOOD
ADVISORIES REMAIN IN EFFECT FOR NORTH-FACING BEACHES OF PUERTO
RICO, WHERE LARGE BREAKING WAVES, LIFE-THREATENING RIP CURRENTS, AND
MINOR COASTAL FLOODING ARE POSSIBLE, ESPECIALLY FROM RINCóN TO
FAJARDO AND AROUND HIGH TIDE. CULEBRA AND THE NORTHERN U.S. VIRGIN
ISLANDS WILL ALSO FACE A LIFE-THREATENING RIP CURRENT RISK. SMALL
CRAFT ADVISORIES REMAIN IN EFFECT ACROSS THE ATLANTIC WATERS AND
CARIBBEAN PASSAGES.
THE RIP CURRENT RISK WILL EXPAND TONIGHT TO THE SOUTHWEST COAST OF
PUERTO RICO AND VIEQUES. WHILE THE NORTHERLY SWELL DECREASES AFTER
THURSDAY MORNING, STRENGTHENING EAST TO EAST-NORTHEAST WINDS WILL
CONTINUE TO SUPPORT LIFE-THREATENING RIP CURRENTS THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK. BEACHGOERS SHOULD STAY OUT OF
THE WATER AT AFFECTED BEACHES.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HIGH RIP CURRENT RISK THROUGH LATE TONIGHT FOR PRZ001-002-005-
008-010-012.
COASTAL FLOOD ADVISORY UNTIL 6 PM AST THIS EVENING FOR PRZ001-
002-005-008-010.
HIGH SURF ADVISORY UNTIL 6 AM AST THURSDAY FOR PRZ001-002-005-
008-010.
HIGH RIP CURRENT RISK FROM 6 PM AST THIS EVENING THROUGH LATE
TONIGHT FOR PRZ011-013.
VI...HIGH RIP CURRENT RISK THROUGH LATE TONIGHT FOR VIZ001.
AM...SMALL CRAFT ADVISORY UNTIL 6 AM AST THURSDAY FOR AMZ711-712-716-
723-726-741-742.
DAY SHIFT...ICP/MMC
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