405
FXCA62 TJSJ 220600
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
200 AM AST THU OCT 22 2026
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 200 AM AST THU OCT 22 2026
* A WETTER PATTERN TODAY THROUGH SATURDAY WILL BRING MORE FREQUENT
SHOWERS AND THUNDERSTORMS, INCLUDING NIGHTTIME ACTIVITY. HEAVY
DOWNPOURS MAY CAUSE URBAN AND SMALL-STREAM FLOODING, RAPID RIVER
RISES, AND ISOLATED FLASH FLOODING. REPEATED RAINFALL WILL ALSO
INCREASE THE POTENTIAL FOR LANDSLIDES ALONG VULNERABLE SLOPES.
* A MODERATE RISK OF RIP CURRENTS WILL PERSIST ALONG EXPOSED
NORTHERN BEACHES TODAY. ANOTHER NORTHERLY SWELL ARRIVING EARLY
FRIDAY WILL BRING A RENEWED HIGH RISK ALONG NORTHERN PUERTO
RICO, WITH DANGEROUS RIP CURRENTS POTENTIALLY CONTINUING THROUGH
THE WEEKEND AND INTO EARLY NEXT WEEK.
* WARM AND HUMID CONDITIONS WILL CONTINUE, PARTICULARLY DURING
PERIODS OF SUNSHINE. HEAT IMPACTS MAY BECOME MORE PRONOUNCED
SUNDAY AND MONDAY, ESPECIALLY ACROSS COASTAL AND URBAN AREAS AND
AMONG INDIVIDUALS SENSITIVE TO HEAT.
SHORT TERM(TODAY THROUGH SATURDAY)
ISSUED AT 200 AM AST THU OCT 22 2026
A TRANSITION TOWARD WETTER CONDITIONS IS EXPECTED ACROSS PUERTO
RICO AND THE U.S. VIRGIN ISLANDS AS DEEPER TROPICAL MOISTURE
SPREADS NORTHWARD INTO THE NORTHEASTERN CARIBBEAN. SURFACE HIGH
PRESSURE OVER THE CENTRAL ATLANTIC AND BROAD TROUGHING NORTHWEST
OF THE REGION WILL MAINTAIN A GENERALLY SOUTHEASTERLY FLOW,
FAVORING PASSING SHOWERS AND ISOLATED THUNDERSTORMS OVER THE
SURROUNDING WATERS, THE U.S. VIRGIN ISLANDS, AND EASTERN AND
SOUTHERN PUERTO RICO DURING THE OVERNIGHT AND MORNING HOURS. THE
LATEST GFS GUIDANCE INDICATES PRECIPITABLE WATER VALUES INCREASING
TO AROUND 2.1 TO 2.2 INCHES TODAY, ACCOMPANIED BY A SUBSTANTIAL
INCREASE IN MID-LEVEL MOISTURE. DURING THE AFTERNOON, DAYTIME
HEATING, SEA-BREEZE CONVERGENCE, AND LOCAL TERRAIN EFFECTS WILL
FAVOR SCATTERED TO NUMEROUS SHOWERS AND ISOLATED TO SCATTERED
THUNDERSTORMS ACROSS INTERIOR, NORTHERN, AND NORTHWESTERN PUERTO
RICO. INCREASING CLOUD COVER MAY LIMIT DAYTIME HEATING IN SOME
AREAS, BUT SUFFICIENT MOISTURE AND INSTABILITY SHOULD REMAIN
AVAILABLE FOR LOCALLY HEAVY RAINFALL. SOME ACTIVITY MAY PERSIST
INTO THE EVENING.
A MOIST AND UNSETTLED PATTERN WILL CONTINUE FRIDAY AND SATURDAY,
WITH PRECIPITABLE WATER VALUES GENERALLY REMAINING NEAR 2.1 TO 2.2
INCHES. SUPPORT FROM THE UPPER-LEVEL TROUGH SHOULD GRADUALLY
WEAKEN AS HEIGHTS RISE AND TEMPERATURES ALOFT WARM. NEVERTHELESS,
ABUNDANT MOISTURE THROUGH THE LOWER AND MIDDLE LEVELS WILL
CONTINUE TO SUPPORT SHOWERS AND THUNDERSTORMS. AT THE SURFACE, A
TIGHTENING PRESSURE GRADIENT BETWEEN THE ATLANTIC RIDGE AND LOW
PRESSURE DEVELOPING NORTHWEST OF THE REGION WILL PROMOTE A MORE
EAST-SOUTHEASTERLY FLOW, WITH WINDS INCREASING FRIDAY. PASSING
SHOWERS WILL CONTINUE TO FAVOR WINDWARD SECTORS DURING THE
OVERNIGHT AND MORNING HOURS, FOLLOWED BY AFTERNOON CONVECTION
ACROSS INTERIOR, NORTHERN, AND WESTERN PUERTO RICO. INCREASING
STEERING WINDS SHOULD HELP SHOWERS MOVE MORE READILY, ALTHOUGH
REPEATED ROUNDS OF RAINFALL MAY STILL AFFECT THE SAME AREAS.
ADDITIONAL SHOWERS AND THUNDERSTORMS OVER THE SURROUNDING WATERS
MAY REACH COASTAL AREAS DURING THE EVENING AND OVERNIGHT HOURS.
THE PRIMARY CONCERN THROUGH THE SHORT-TERM PERIOD WILL BE LOCALLY
HEAVY RAINFALL CAPABLE OF PRODUCING URBAN AND SMALL-STREAM
FLOODING, RAPID RIVER RISES, AND ISOLATED FLASH FLOODING,
PARTICULARLY WHERE SHOWERS MOVE SLOWLY OR REPEATEDLY AFFECT THE
SAME LOCATIONS. AS RAINFALL ACCUMULATES OVER SEVERAL DAYS,
LANDSLIDES WILL BECOME A GREATER CONCERN ALONG STEEP AND
VULNERABLE SLOPES. THE STRONGEST THUNDERSTORMS MAY ALSO PRODUCE
FREQUENT LIGHTNING AND GUSTY WINDS. THESE HAZARDS WILL NOT BE
CONFINED TO THE AFTERNOON, AS SHOWERS AND THUNDERSTORMS MAY
CONTINUE OR REDEVELOP DURING THE EVENING AND OVERNIGHT HOURS.
CONFIDENCE REMAINS HIGH IN THE WETTER PATTERN, WHILE THE TIMING
AND PLACEMENT OF THE HEAVIEST RAINFALL WILL DEPEND ON CLOUD COVER,
LOCAL CONVERGENCE, AND THE EVOLUTION OF INDIVIDUAL SHOWERS AND
THUNDERSTORMS. WARM AND HUMID CONDITIONS WILL PERSIST BETWEEN
PERIODS OF RAINFALL, WITH SOME HEAT IMPACTS POSSIBLE DURING
PROLONGED BREAKS IN CLOUD COVER.
LONG TERM(SUNDAY THROUGH THURSDAY)
ISSUED AT 200 AM AST THU OCT 22 2026
WET AND UNSETTLED CONDITIONS WILL CONTINUE INTO SUNDAY BEFORE
GRADUALLY IMPROVING EARLY NEXT WEEK AS DRIER AND MORE STABLE AIR
SPREADS ACROSS THE REGION. SURFACE HIGH PRESSURE OVER THE CENTRAL
ATLANTIC AND LOWER PRESSURE TO THE NORTHWEST WILL MAINTAIN A
SOUTHEASTERLY FLOW, KEEPING TROPICAL MOISTURE OVER PUERTO RICO AND THE
U.S. VIRGIN ISLANDS. PRECIPITABLE WATER VALUES NEAR 2.0 TO 2.2
INCHES AND SUFFICIENT MID-LEVEL MOISTURE WILL SUPPORT PASSING
SHOWERS AND ISOLATED THUNDERSTORMS ACROSS WINDWARD SECTORS DURING
THE OVERNIGHT AND MORNING HOURS. DURING THE AFTERNOON, DAYTIME
HEATING, SEA-BREEZE CONVERGENCE, AND LOCAL TERRAIN EFFECTS WILL
FAVOR ADDITIONAL SHOWERS AND THUNDERSTORMS ACROSS INTERIOR,
NORTHERN, AND WESTERN PUERTO RICO. ALTHOUGH THE OVERALL RAINFALL
THREAT SHOULD BE LOWER THAN DURING THE PRECEDING DAYS, LOCALLY
HEAVY DOWNPOURS MAY STILL CAUSE URBAN AND SMALL-STREAM FLOODING
WHERE SHOWERS REPEATEDLY AFFECT THE SAME AREAS. RAINFALL
ACCUMULATED DURING THE SHORT-TERM PERIOD MAY ALSO LEAVE VULNERABLE
SLOPES MORE SUSCEPTIBLE TO LANDSLIDES.
A MORE NOTICEABLE DRYING TREND IS EXPECTED MONDAY AS DRIER AIR
FILTERS INTO THE MIDLEVELS AND AVAILABLE MOISTURE BECOMES
INCREASINGLY CONFINED TO THE LOWER PORTION OF THE ATMOSPHERE.
PRECIPITABLE WATER VALUES SHOULD DECREASE TOWARD SEASONAL LEVELS,
ALTHOUGH RESIDUAL MOISTURE AND LOCAL EFFECTS WILL CONTINUE TO
SUPPORT AFTERNOON SHOWERS AND ISOLATED THUNDERSTORMS, MAINLY
ACROSS INTERIOR AND WESTERN PUERTO RICO. LIGHTER STEERING WINDS
COULD ALLOW LOCALIZED RAINFALL ACCUMULATIONS, MAINTAINING SOME
FLOODING POTENTIAL DESPITE DECREASING OVERALL SHOWER COVERAGE.
WARM AND HUMID CONDITIONS WILL ALSO REMAIN A CONCERN, PARTICULARLY
SUNDAY AND MONDAY, WHEN PERIODS OF SUNSHINE MAY INCREASE HEAT
IMPACTS ACROSS COASTAL AND URBAN AREAS AND AMONG HEAT-SENSITIVE
INDIVIDUALS.
FROM TUESDAY THROUGH THURSDAY, A BUILDING MID-LEVEL RIDGE AND
INCREASINGLY LIMITED MOISTURE SHOULD FAVOR A DRIER AND MORE STABLE
WEATHER PATTERN. SUBSIDENCE AND WARMING ALOFT WILL SUPPRESS
WIDESPREAD CONVECTIVE DEVELOPMENT AS PRECIPITABLE WATER VALUES
TREND BELOW NORMAL. BRIEF PASSING SHOWERS AND ISOLATED AFTERNOON
CONVECTION WILL REMAIN POSSIBLE, BUT THE POTENTIAL FOR WIDESPREAD
HEAVY RAINFALL AND FLOODING SHOULD DIMINISH AS THE WEEK
PROGRESSES.
AVIATION
(06Z TAFS)
ISSUED AT 200 AM AST THU OCT 22 2026
MAINLY VFR CONDS EXPECTED, WITH VCSH AT TJPS/TIST/TISX OVERNIGHT
INTO THE MORNING AS MOISTURE INCREASES FROM THE S. SHRA/TSRA
DEVELOPING OVER INTERIOR AND NORTHERN PR AFT 22/17Z MAY PRODUCE
PERIODS OF MVFR AND BRIEF IFR CIGS/VSBYS WITH DIRECT +RA/TSRA
PASSAGE AT TJBQ AND POSSIBLY TJSJ, WITH TJBQ IMPACTS FAVORED LATER
IN THE 22/17-23Z PERIOD. BRIEF MVFR VSBYS ALSO PSBL WITH PASSING
SHRA AT USVI TERMINALS. SFC WINDS L/V OVERNIGHT, BCMG ESE-SE AT
8-10 KT AFT 22/13Z, WITH SEA-BREEZE VARIATIONS AND LOCALLY GUSTY
WINDS NEAR TSRA.
MARINE
ISSUED AT 200 AM AST THU OCT 22 2026
LIGHT TO GENTLE SOUTHEASTERLY WINDS WILL BECOME EAST TO SOUTHEAST
AND INCREASE TO MODERATE TO LOCALLY FRESH SPEEDS FRIDAY INTO THE
WEEKEND AS THE PRESSURE GRADIENT TIGHTENS. THE CURRENT NORTHERLY
SWELL WILL CONTINUE TO SUBSIDE TODAY BEFORE ANOTHER NORTH-
NORTHWESTERLY SWELL ARRIVES EARLY FRIDAY, FOLLOWED BY ADDITIONAL
PULSES THROUGH THE WEEKEND. SEAS WILL BUILD TO 5 TO 6 FEET ACROSS
PORTIONS OF THE ATLANTIC WATERS AND MONA PASSAGE, GENERALLY
REMAINING BELOW SMALL CRAFT ADVISORY CRITERIA, ALTHOUGH SMALL
CRAFT SHOULD EXERCISE CAUTION. MORE FREQUENT SHOWERS AND
THUNDERSTORMS, INCLUDING NIGHTTIME ACTIVITY, WILL BRING LIGHTNING,
GUSTY WINDS, REDUCED VISIBILITY, AND LOCALLY HIGHER SEAS.
BEACH FORECAST
ISSUED AT 200 AM AST THU OCT 22 2026
SUBSIDING NORTHERLY SWELL WILL ALLOW A MODERATE RISK OF RIP
CURRENTS TODAY ALONG EXPOSED BEACHES OF NORTHERN AND NORTHWESTERN
PUERTO RICO, CULEBRA, ST. THOMAS, AND ST. JOHN. ANOTHER NORTH-
NORTHWESTERLY SWELL ARRIVING EARLY FRIDAY WILL BRING A RENEWED
HIGH RISK ALONG NORTHERN PUERTO RICO, WHERE BREAKING WAVES AROUND
6 FEET ARE FORECAST FRIDAY AND SATURDAY. ADDITIONAL SWELL PULSES
MAY MAINTAIN DANGEROUS RIP CURRENTS THROUGH THE WEEKEND AND INTO
EARLY NEXT WEEK. INCREASING SHOWER AND THUNDERSTORM ACTIVITY WILL
ALSO BRING LIGHTNING AND GUSTY WINDS TO COASTAL AREAS. BEACHGOERS
SHOULD AVOID SWIMMING WHERE THE RIP CURRENT RISK IS HIGH AND SEEK
SHELTER INDOORS WHEN THUNDERSTORMS APPROACH.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
EVE...MRR/MMC
MID...ICP
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page