582
FXCA62 TJSJ 270801
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
401 AM AST MON OCT 27 2025
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST
KEY MESSAGES
* SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP, ONCE
AGAIN, THIS AFTERNOON OVER CENTRAL PUERTO RICO EARLY THIS
AFTERNOON AND SPREADING TOWARD THE NORTHWEST PORTIONS OF PUERTO
RICO. THEREFORE, MAINTAINING A LIMITED TO ELEVATED FLOODING RISK
FOR THESE AREAS.
* ACROSS THE U.S. VIRGIN ISLANDS, ISOLATED TO SCATTERED SHOWERS
ARE EXPECTED FROM TIME TO TIME, PARTICULARLY DURING THE MORNING
HOURS.
* A MODERATE RISK OF RIP CURRENTS WILL CONTINUE FOR MOST BEACHES
OF PUERTO RICO AND THE U.S. VIRGIN ISLANDS THROUGH LATE TUESDAY,
INCREASING TO A HIGH RISK ACROSS NORTH- EXPOSED BEACHES BY MID-WEEK.
SHORT TERM...TODAY THROUGH WEDNESDAY
ISSUED AT 351 AM AST MON OCT 27 2025
SHOWERS AND A FEW THUNDERSTORMS MOVED ACROSS THE REGION OVERNIGHT,
MAINLY AFFECTING THE EASTERN HALF OF PUERTO RICO WHILE THE U.S.
VIRGIN ISLANDS SAW LESS ACTIVITY. RADAR ESTIMATES INDICATE AROUND A
QUARTER INCH OF RAIN, WITH ISOLATED AREAS IN SOUTHEASTERN PUERTO
RICO RECEIVING UP TO HALF AN INCH. STEERING FLOW WAS GENERALLY FROM
THE EAST-SOUTHEAST, THOUGH WINDS OVER EXPOSED COASTAL AREAS WERE
LIGHT FROM THE EAST TO EAST-NORTHEAST AT 5–10 KNOTS, BECOMING
LIGHTER TO CALM AND VARIABLE ELSEWHERE. OVERNIGHT LOWS RANGED FROM
THE LOW 60S IN THE MOUNTAINS TO THE UPPER 70S ALONG THE COAST, WITH
A FEW EXPOSED COASTAL SITES IN EASTERN PUERTO RICO, CULEBRA, AND THE
USVI REMAINING AT OR SLIGHTLY ABOVE 80°F.
A MOIST AND MARGINALLY UNSTABLE WEATHER PATTERN WILL PERSIST ACROSS
THE LOCAL ISLANDS THROUGH MIDWEEK AS HURRICANE MELISSA SLOWLY MOVES
NORTHWARD WELL NORTHWEST OF THE AREA. THE SYSTEM’S BROAD
CIRCULATION, IN COMBINATION WITH A STRENGTHENING SURFACE HIGH
PRESSURE OVER THE CENTRAL ATLANTIC, WILL MAINTAIN A SOUTHEASTERLY TO
SOUTHERLY WIND FLOW ACROSS PUERTO RICO AND THE U.S. VIRGIN ISLANDS,
PARTICULARLY TUESDAY ONWARDS. THIS PATTERN WILL CONTINUE TO DRAW
DEEP TROPICAL COLUMNAR MOISTURE ACROSS THE REGION, WITH PRECIPITABLE
WATER VALUES EXCEEDING TWO INCHES AND OCCASIONALLY REACHING AROUND
2.3 INCHES, WHICH IS WELL ABOVE THE CLIMATOLOGICAL NORMAL.
SUCH MOISTURE LEVELS, IN COMBINATION WITH DIURNAL HEATING AND LOCAL
EFFECTS, WILL FAVOR AFTERNOON CONVECTION, PARTICULARLY ACROSS THE
INTERIOR AND NORTHWESTERN TO NORTH-CENTRAL PUERTO RICO, WHERE SEA
BREEZE BOUNDARIES ARE EXPECTED TO CONVERGE WITH TOPOGRAPHICALLY
DRIVEN CONVECTION DEVELOPING OVER THE MOUNTAINOUS INTERIOR,
ENHANCING SHOWER AND THUNDERSTORM ACTIVITY. IN ADDITION, STREAMER-
LIKE SHOWERS ARE EXPECTED TO DEVELOP OVER AND DOWNWIND OF THE U.S.
VIRGIN ISLANDS AND OTHER SMALLER ISLANDS. ALTHOUGH THE DEVELOPMENT
OF AN UPPER-LEVEL RIDGE WILL LIMIT LARGE-SCALE ASCENT AND WIDESPREAD
CONVECTION, THE AVAILABLE MOISTURE AND INSTABILITY WILL STILL ALLOW
FOR LOCALIZED HEAVY SHOWERS AND ISOLATED THUNDERSTORMS. AS A RESULT,
LIMITED TO ELEVATED FLOODING IMPACTS WILL REMAIN POSSIBLE IN URBAN
AREAS, POOR-DRAINAGE SPOTS, AND ALONG SMALL STREAMS DURING THE
AFTERNOON HOURS. PASSING SHOWERS WILL CONTINUE TO AFFECT THE U.S.
VIRGIN ISLANDS AND EASTERN PUERTO RICO DURING THE NIGHTTIME AND
EARLY MORNING HOURS.
THE PRESSURE GRADIENT IS ALSO EXPECTED TO TIGHTEN ACROSS THE
NORTHEASTERN CARIBBEAN DUE TO THE INTERACTION BETWEEN HURRICANE
MELISSA, AS IT MOVES NORTHWARD, AND THE SURFACE ATLANTIC RIDGE,
RESULTING IN BREEZY TO LOCALLY WINDY CONDITIONS, PARTICULARLY ACROSS
COASTAL AREAS. THE COMBINATION OF THE PERSISTENT SOUTHERLY WIND FLOW
AND ELEVATED MOISTURE CONTENT WILL ALSO RESULT IN ABOVE-NORMAL
TEMPERATURES AND HEAT INDICES, ESPECIALLY ACROSS COASTAL AND URBAN
AREAS, WHERE HEAT INDICES MAY REACH OR EXCEED THE MID-100S. OVERALL,
A WARM, HUMID, AND BREEZY PATTERN WILL DOMINATE THROUGH AT LEAST
WEDNESDAY, WITH LOCALIZED FLOODING AND ELEVATED HEAT INDICES
REMAINING THE PRIMARY WEATHER HAZARDS.
LONG TERM...THURSDAY THROUGH MONDAY
ISSUED AT 351 AM AST MON OCT 27 2025
THE LONG-TERM FORECAST ACROSS THE AREA WILL BE DEPENDENT ON THE
TRACK OF MAJOR HURRICANE MELISSA ONCE IT ENTERS THE WESTERN ATLANTIC
WATERS AND MOVES NORTH OF THE SOUTHEASTERN BAHAMAS AND THE TURKS AND
CAICOS ISLANDS. TRAILING MOISTURE ASSOCIATED WITH MELISSA WILL BEGIN
TO REACH THE LOCAL AREA FROM THURSDAY INTO FRIDAY. ALTHOUGH THE BULK
OF THE MOISTURE IS EXPECTED TO REMAIN OVER HISPANIOLA AND TO THE
WEST OF THE LOCAL AREA, SUFFICIENT MOISTURE CONTENT (WITH
PRECIPITABLE WATER VALUES UP TO 2.25 INCHES) WILL SUPPORT THE
DEVELOPMENT OF AFTERNOON CONVECTIVE ACTIVITY ACROSS THE REGION,
PARTICULARLY OVER NORTHWESTERN PUERTO RICO. BY LATE FRIDAY INTO THE
WEEKEND, THE MOISTURE ASSOCIATED WITH MELISSA WILL BEGIN TO MOVE
AWAY FROM THE AREA AS A STRONG SURFACE HIGH-PRESSURE SYSTEM BUILDS
OVER THE CENTRAL ATLANTIC. THEREFORE, WINDS WILL BE PREVAILING FROM
THE SOUTHEASTERLY-SOUTHERLY DIRECTION THROUGH SATURDAY, WHEN THE
WIND PATTERN WILL SHIFT TO THE EAST IN RESPONSE TO THE SURFACE HIGH.
THIS WEATHER PATTERN WILL LIKELY PREVAIL INTO EARLY NEXT WEEK WITH
AN ADVECTIVE PATTERN PERSISTING DURING THE OVERNIGHT AND MORNING
HOURS. SUBSEQUENTLY, SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED
DURING THE AFTERNOON HOURS ALONG THE CENTRAL MOUNTAIN RANGE AND THE
NORTHWESTERN QUADRANT OF THE ISLAND DUE TO DAYTIME HEATING AND LOCAL
EFFECTS. THE FLOODING THREAT WILL REMAIN LIMITED BUT ELEVATED ACROSS
THE AFOREMENTIONED AREAS.
AVIATION
(06Z TAFS)
ISSUED AT 351 AM AST MON OCT 27 2025
MAINLY VFR CONDS EXPECTED THRU PRD. BRIEF MVFR CONDS PSBL IN
SHRA/TSRA WITH BRIEF REDUCTIONS IN VIS/CIGS MAINLY AFT 27/17Z,
AFFECTING PARTICULARLY TJBQ/TJSJ. WINDS BCMG SE 10-15 KT AFT 27/13Z,
WITH HIGHER GUSTS PSBL, ESP NR TSRA. WINDS BCM LGT/VRB AFT 27/23Z
WITH LAND BREEZE INFLUENCE.
MARINE
ISSUED AT 351 AM AST MON OCT 27 2025
MODERATE TO LOCALLY FRESH EASTERLY WINDS WILL PREVAIL THROUGH LATE
TONIGHT INTO TUESDAY, GRADUALLY SHIFTING FROM THE SOUTHEAST TO SOUTH
BY TUESDAY AS MAJOR HURRICANE MELISSA MOVES OVER JAMAICA INTO THE
HISPANIOLA AND A HIGH PRESSURE BUILDS OVER THE EASTERN ATLANTIC. SEAS
WILL INCREASE TO CAUTIONARY LEVELS BY WEDNESDAY ACCOMPANIED BY SHOWERS
AND THUNDERSTORMS ASSOCIATED WITH MELISSA'S MOISTURE FIELD LEADING
TO PERIODS OF LOCALIZED HAZARDOUS MARINE CONDITIONS.
BEACH FORECAST
ISSUED AT 351 AM AST MON OCT 27 2025
A MODERATE RISK OF RIP CURRENTS WILL CONTINUE TUESDAY FOR MOST
BEACHES IN PUERTO RICO AND THE U.S. VIRGIN ISLANDS. BY MIDWEEK,
THE RISK OF RIP CURRENT THREAT WILL INCREASE TO A HIGH RISK ALONG
SOME OF THE NORTH FACING BEACHES OF PUERTO RICO AND USVI DUE TO A
SMALL NORTHWEST SWELL FROM MAJOR HURRICANE MELISSA. BEACHGOERS
ARE ADVISED TO CLOSELY MONITOR THE LOCAL FORECAST AS WELL AS THE
EVOLUTION AND TRACK OF MAJOR HURRICANE MELISSA FOR UPDATED
INFORMATION. IN ADDITION, SHOWERS AND ISOLATED THUNDERSTORMS CAN
FORM NEAR COASTAL AREAS, ESPECIALLY DURING AFTERNOON HOURS. ANYONE
OUTDOORS SHOULD STAY ALERT FOR RAPIDLY CHANGING WEATHER AND MOVE
INDOORS OR SEEK SHELTER IMMEDIATELY IF THUNDER IS HEARD.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
MIDNIGHT SHIFT...ICP/CVB/GRS
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