063
FXCA62 TJSJ 190530
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
130 AM AST MON OCT 19 2026
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
ISSUED AT 130 AM AST MON OCT 19 2026
* SLOW-MOVING THUNDERSTORMS MAY PRODUCE HEAVY RAINFALL LOCALLY AND
ISOLATED URBAN AND SMALL-STREAM FLOODING THIS AFTERNOON.
STRONGER STORMS MAY PRODUCE FREQUENT LIGHTNING AND GUSTY WINDS.
* HEAT WILL PRIMARILY AFFECT HEAT-SENSITIVE INDIVIDUALS OUTDOORS
WITHOUT EFFECTIVE COOLING OR ADEQUATE HYDRATION, ESPECIALLY
DURING THE LATE MORNING AND EARLY AFTERNOON.
* MODERATE RIP CURRENT RISK IS EXPECTED TODAY ALONG EXPOSED
ATLANTIC-FACING BEACHES OF PUERTO RICO AND THE U.S. VIRGIN
ISLANDS. A MORE ENERGETIC NORTHWESTERLY SWELL ARRIVING TONIGHT
WILL BRING BUILDING SEAS, HIGHER SURF, AND INCREASINGLY
HAZARDOUS RIP CURRENTS THROUGH MIDWEEK. THE SWELL WILL PEAK
TUESDAY AND SHIFT TO A NORTHERLY DIRECTION WEDNESDAY.
SHORT TERM(TODAY THROUGH WEDNESDAY)
ISSUED AT 130 AM AST MON OCT 19 2026
LINGERING SHOWERS OVER THE LOCAL WATERS AND WINDWARD AREAS SHOULD
GRADUALLY DIMINISH THIS MORNING, GIVING WAY TO HOT AND HUMID
CONDITIONS BEFORE AFTERNOON CONVECTION DEVELOPS. A WEAK PRESSURE
GRADIENT WILL MAINTAIN LIGHT EAST-SOUTHEAST WINDS, ALLOWING SEA
BREEZES AND TERRAIN EFFECTS TO DOMINATE. MEANWHILE, A WEAKENING
MID-LEVEL RIDGE AND A TROUGH NORTHEAST OF THE REGION WILL
GRADUALLY REDUCE SUBSIDENCE. DESPITE SLIGHTLY BELOW-NORMAL
MOISTURE (PWAT 1.7–1.8 INCHES) AND RELATIVELY DRY MID-LEVELS,
DAYTIME HEATING AND LOCAL CONVERGENCE WILL SUPPORT SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS INTERIOR AND WESTERN PUERTO RICO.
WEAK STEERING WINDS WILL FAVOR SLOW-MOVING ACTIVITY BEFORE
CONVECTION SUBSIDES THIS EVENING, WITH PASSING SHOWERS RETURNING
TO WINDWARD AREAS AND THE SURROUNDING WATERS OVERNIGHT.
A SIMILAR PATTERN WILL PERSIST TUESDAY, ALTHOUGH INCREASINGLY
SOUTHERLY FLOW ALOFT MAY EXTEND AFTERNOON CONVECTION INTO NORTHERN
PUERTO RICO. MOISTURE WILL DECREASE FURTHER BELOW SEASONAL LEVELS
(PWAT 1.5–1.6 INCHES) TUESDAY NIGHT INTO WEDNESDAY, LIMITING
SHOWER COVERAGE AND FAVORING THE DRIEST CONDITIONS OF THE PERIOD.
NEVERTHELESS, LOCAL EFFECTS MAY STILL TRIGGER AFTERNOON SHOWERS.
THIS IMPROVEMENT WILL BE BRIEF AS ABOVE-NORMAL TROPICAL MOISTURE
(PWAT EXCEEDING 2 INCHES) RETURNS LATE WEDNESDAY INTO THURSDAY.
MEANWHILE, SOUTHEAST FLOW WILL MAINTAIN ABOVE-NORMAL TEMPERATURES,
PARTICULARLY ACROSS NORTHERN COASTAL AND URBAN AREAS.
THE MAIN HAZARDS THROUGH TUESDAY WILL BE LOCALLY HEAVY RAINFALL,
LIGHTNING, AND GUSTY WINDS FROM SLOW-MOVING THUNDERSTORMS, WITH
ISOLATED URBAN AND SMALL-STREAM FLOODING POSSIBLE ACROSS INTERIOR
AND WESTERN PUERTO RICO. RAINFALL AND LIGHTNING THREATS SHOULD
DECREASE WEDNESDAY. LIMITED HEAT IMPACTS WILL PERSIST DAILY,
PRIMARILY AFFECTING HEAT-SENSITIVE INDIVIDUALS OUTDOORS WITHOUT
ADEQUATE COOLING OR HYDRATION, ESPECIALLY DURING THE LATE MORNING
AND EARLY AFTERNOON. RAINFALL IMPACTS ACROSS THE U.S. VIRGIN
ISLANDS SHOULD REMAIN GENERALLY LIMITED THROUGHOUT THE PERIOD.
LONG TERM(THURSDAY THROUGH MONDAY)
ISSUED AT 130 AM AST MON OCT 19 2026
NO MAJOR CHANGES TO THE LONG-TERM FORECAST. A SOUTHEAST TO
SOUTHERLY STEERING FLOW WILL PERSIST ACROSS THE REGION DUE TO THE
INTERACTION BETWEEN A DEEP-LAYER LOW MOVING ACROSS THE EASTERN
CONUS AND SURFACE HIGH PRESSURE OVER THE CENTRAL ATLANTIC. DEEP
TROPICAL MOISTURE WILL RETURN THURSDAY, WITH PRECIPITABLE WATER
VALUES GENERALLY AROUND OR EXCEEDING 2 INCHES THROUGH MUCH OF THE
PERIOD. ALTHOUGH A MID-LEVEL RIDGE IS EXPECTED TO BUILD OVER THE
EASTERN CARIBBEAN, ABUNDANT MOISTURE, DAYTIME HEATING, SEA BREEZE
CONVERGENCE, AND LOCAL TOPOGRAPHIC EFFECTS WILL CONTINUE TO
SUPPORT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. PASSING
SHOWERS WILL FAVOR WINDWARD AREAS DURING THE OVERNIGHT AND MORNING
HOURS, FOLLOWED BY AFTERNOON CONVECTION ACROSS INTERIOR PUERTO
RICO, SPREADING TOWARD NORTHERN AND WESTERN SECTIONS. INCREASING
STEERING WINDS THURSDAY THROUGH SATURDAY SHOULD FAVOR MORE
PROGRESSIVE CONVECTION. HOWEVER, WEAKENING WINDS LATE IN THE
WEEKEND INTO EARLY NEXT WEEK MAY ALLOW SLOWER-MOVING OR REPEATEDLY
DEVELOPING THUNDERSTORMS, INCREASING LOCALIZED RAINFALL
ACCUMULATIONS. THE MAIN HAZARDS WILL BE LIGHTNING, URBAN AND
SMALL-STREAM FLOODING, AND ISOLATED FLASH FLOODING WHERE HEAVIER
RAINFALL PERSISTS, PARTICULARLY DURING THE AFTERNOON HOURS.
MEANWHILE, THE PREVAILING SOUTHEAST TO SOUTHERLY FLOW WILL
MAINTAIN HOT AND HUMID CONDITIONS, ESPECIALLY ACROSS NORTHERN
COASTAL AND URBAN AREAS OF PUERTO RICO. HEAT IMPACTS WILL
PRIMARILY AFFECT HEAT-SENSITIVE INDIVIDUALS OUTDOORS WITHOUT
EFFECTIVE COOLING OR ADEQUATE HYDRATION DURING THE LATE MORNING
AND EARLY AFTERNOON.
AVIATION
(06Z TAFS)
ISSUED AT 130 AM AST MON OCT 19 2026
VFR CONDS EXPECTED TO PREVAIL ACROSS MOST TERMINALS THROUGH THE
TAF PRD. BRIEF SHRA MAY AFFECT TJSJ AND USVI TERMINALS THROUGH
19/14Z. AFT 19/16-18Z, SHRA/TSRA DEVELOPMENT ACROSS INTERIOR AND
WESTERN PR MAY PRODUCE MVFR/IFR CONDS, PARTICULARLY NEAR TJBQ AND
TJSJ, WITH VCTS POSSIBLE NEAR TJBQ. MOUNTAIN OBSCURATIONS AND
LOCALLY GUSTY WINDS POSSIBLE NEAR STRONGER TSRA. ACTIVITY SHOULD
DIMINISH AFT 19/22-23Z. LIGHT ESE- SE WINDS AT 5-10 KT WILL
PREVAIL, INCREASING TO 8-12 KT WITH AFTERNOON SEA BREEZE
VARIATIONS.
MARINE
ISSUED AT 130 AM AST MON OCT 19 2026
GENTLE TO MODERATE EAST-SOUTHEAST WINDS WILL PREVAIL THROUGH
MIDWEEK UNDER A WEAK PRESSURE GRADIENT. AN ENERGETIC, LONG-PERIOD
NORTHWESTERLY SWELL WILL ARRIVE TONIGHT, PEAK TUESDAY, AND BECOME
NORTHERLY BY WEDNESDAY. INITIAL SWELL PERIODS OF 13 TO 15 SECONDS
WILL ACCOMPANY BUILDING SEAS OF 5 TO 7 FEET ACROSS THE ATLANTIC
WATERS AND EXPOSED PASSAGES. HAZARDOUS CONDITIONS FOR SMALL CRAFT
ARE POSSIBLE TUESDAY, WITH SEAS GRADUALLY SUBSIDING WEDNESDAY INTO
THURSDAY. AFTERNOON THUNDERSTORMS MAY ALSO PRODUCE LOCALLY GUSTY
WINDS, LIGHTNING, AND REDUCED VISIBILITY IN HEAVY RAINFALL.
BEACH FORECAST
ISSUED AT 130 AM AST MON OCT 19 2026
A MODERATE RISK OF RIP CURRENTS WILL CONTINUE TODAY ALONG EXPOSED
NORTHERN BEACHES OF PUERTO RICO. CONDITIONS WILL DETERIORATE
TONIGHT AS A LONG-PERIOD NORTHWESTERLY SWELL ARRIVES, PEAKING
TUESDAY WITH BREAKING WAVES OF 6 TO 8 FEET ALONG EXPOSED
SHORELINES. A HIGH RISK OF LIFE-THREATENING RIP CURRENTS IS
LIKELY ACROSS NORTHERN, NORTHWESTERN, AND WESTERN PUERTO RICO,
INCLUDING RINCON. THEREFORE, A RIP CURRENT STATEMENT WILL LIKELY
BE ISSUED LATER TODAY. ACROSS THE U.S. VIRGIN ISLANDS, A MODERATE
RISK IS EXPECTED AROUND ST. THOMAS AND ST. JOHN TUESDAY, WITH
GENERALLY LOWER RISKS ELSEWHERE. HAZARDOUS SURF AND RIP CURRENTS
MAY PERSIST WEDNESDAY AS THE SWELL BECOMES NORTHERLY. BEACHGOERS
SHOULD ALSO REMAIN ALERT FOR LIGHTNING ASSOCIATED WITH AFTERNOON
THUNDERSTORMS.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
SHORT/AVIATION
ICP
LONG/MARINE/BEACH
MRR/GRS
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