793
FXCA62 TJSJ 192158
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
558 PM AST WED MAR 19 2025
SYNOPSIS
WEATHER CONDITIONS WILL IMPROVE GRADUALLY ON THURSDAY. HOWEVER,RAINFALL
ACTIVITY IS ANTICIPATED BY THE WEEKEND WITH PWAT VALUES
INCREASING FROM FRIDAY INTO SATURDAY. A LONG- PERIOD NORTHWESTERLY
SWELL WILL CREATE HAZARDOUS MARINE AND COASTAL CONDITIONS FROM
THURSDAY ONWARD. THEREFORE, WE URGE PEOPLE TO STAY INFORMED WITH
THE LATEST UPDATES.
SHORT TERM...TONIGHT THROUGH FRIDAY
AS A COLD FRONT MOVES THROUGH OUR AREA TODAY, SOME SHOWERS HAVE BEEN
OBSERVED DURING THE MORNING HOURS ACROSS THE NORTHWEST AND, DURING
THE EARLY AFTERNOON, FURTHER INLAND AND TO THE EAST. RADAR ESTIMATES
INDICATE MINIMAL ACCUMULATIONS, JUST LOCALIZED AREAS IN THE
INTERIOR OBSERVED AROUND 0.25 INCH OF RAIN. DAYTIME HIGH
TEMPERATURES REACHED THE LOW TO MID 80S, PARTICULARLY ACROSS
COASTAL AREAS OF THE ISLANDS, AND STAYED MAINLY IN THE 70S ACROSS
THE MOUNTAINS. MINIMUM TEMPERATURES THIS MORNING FELT COOLER THAN
NORMAL, WITH SOME STATIONS ACROSS THE INTERIOR DROPPING EVEN INTO
THE MID 50S TO LOW 60S, AND MAINLY LOW 70S ALONG COASTAL AREAS.
TONIGHT INTO THURSDAY, WEATHER CONDITIONS ARE EXPECTED TO REMAIN
STABLE AND PLEASANT FOR MOST OF THE FORECAST AREA, WITH LIGHTER
WINDS FROM THE NORTH-NORTHEAST TO KIND OF VARIABLE. DRIER AIR IN
THE WAKE OF THE FRONTAL PASSAGE WILL CAUSE A SHARP DECLINE IN
MOISTURE CONTENT TO AROUND 0.7 INCHES. ADDITIONALLY, AS SUGGESTED
BY BELOW-NORMAL 925 MB TEMPERATURES, COOLER-THAN-NORMAL
TEMPERATURES ARE EXPECTED DURING THIS OVERNIGHT PERIOD AND
THURSDAY MORNING.
THEN, THE LINGERING FRONT WILL INTERACT WITH AN INDUCED DISTURBANCE
NEAR THE SOUTHEAST CARIBBEAN FROM THURSDAY NIGHT INTO FRIDAY,
LIFTING ABUNDANT MOISTURE NEAR ST. CROIX AND SPREADING INTO THE REST
OF THE ISLANDS AS EARLY AS THURSDAY AFTERNOON INTO FRIDAY. AS A
RESULT, PWAT VALUES WILL GRADUALLY INCREASE TO NEAR CLIMATOLOGICAL
LEVELS BY THURSDAY NIGHT LIKELY ENHANCING SHOWER ACTIVITY ACROSS THE
REGION, WITH THE POTENTIAL FOR ISOLATED FLOODING IMPACTS ONCE
AGAIN.
LONG TERM...SATURDAY THROUGH WEDNESDAY
//FROM PREVIOUS DISCUSSION//
A SURFACE-INDUCED TROUGH WILL PROMOTE WET AND UNSTABLE WEATHER
CONDITIONS ON SATURDAY. A GRADUAL INCREASE IN MOISTURE IS EXPECTED
FROM SATURDAY ONWARDS WITH PRECIPITABLE WATER VALUES (PWAT) FROM 1.4
TO 1.8 INCHES. THEREFORE, THE MOISTURE INCREASE IN COMBINATION WITH
DAYTIME HEATING AND LOCAL EFFECTS WILL FAVOR THE DEVELOPMENT OF
SHOWER ACTIVITY ACROSS PORTIONS OF THE INTERIOR AND WESTERN PUERTO
RICO DURING THE AFTERNOON HOURS. WITH THE EXPECTED ACTIVITY, THERE
IS AN INCREASED POTENTIAL OF ISOLATED FLOODING IMPACTS MAINLY IN
URBAN AND LOW-LAYING AREAS.
A STRONG SURFACE HIGH PRESSURE MOVING FROM THE WESTERN ATLANTIC INTO
THE CENTRAL ATLANTIC WILL PROMOTE AN EASTERLY WIND FLOW THROUGH AT
LEAST WEDNESDAY WHEN WINDS WILL BECOME FROM THE SOUTHEAST. IN THE
MID-LEVELS A RIDGE WILL BUILD OVER THE NORTHEASTERN CARIBBEAN REGION
PROMOTING DRIER AIR INTRUSION AND STABLE CONDITIONS ALOFT. HOWEVER,
PATCHES OF LOW-LEVEL MOISTURE WILL CONTINUE TO MOVE INTO THE AREA
FROM THE EAST PROMOTING PASSING TRADE WIND SHOWERS DURING THE
MORNING HOURS ACROSS THE U.S. VIRGIN ISLANDS AND EASTERN PUERTO
RICO. THE 925 MB TEMPERATURES WILL GRADUALLY INCREASE OVER THE
WEEKEND WITH TEMPERATURES AT NORMAL AND ABOVE-NORMAL
CLIMATOLOGICAL VALUES. AT THIS TIME HIGHS ARE EXPECTED TO RANGE
FROM UPPER 80S TO LOW 90S ALONG THE COASTAL AND URBAN AREAS, AND
FROM THE UPPER 70S TO THE LOW TO MID 80S IN THE MOUNTAINS AND
HIGHER TERRAINS.
AVIATION
(18Z TAFS)
MAINLY VFR CONDITIONS ARE EXPECTED THIS FORECAST PERIOD. ADDITIONAL
VCSH TO -SHRA ARE LIKELY MAINLY ACROSS TJPS AND AND USVI TERMINALS
TONIGHT, AND DRIER CONDITIONS ARE FORECAST FOR TOMORROW. NW TO N
WINDS ARE EXPECTED AT AROUND 10 KNOTS OR LESS, WITH SEA BREEZE
VARIATIONS BTWN 20/14-19/23Z.
MARINE
A SERIES OF SURFACE LOW PRESSURE SYSTEMS OVER THE NORTH ATLANTIC
WILL CONTINUE TO BRING NORTHERLY SWELLS ACROSS THE LOCAL WATERS OVER
THE NEXT FEW DAYS. THESE SWELLS WILL CREATE HAZARDOUS SEAS FOR SMALL
CRAFT THROUGH THE END OF THE WORKWEEK. IN THE MEANTIME, AS A FRONTAL
BOUNDARY CROSSES THE LOCAL AREA, EXPECT WINDS TO STRENGTHEN AND TURN
FROM THE NORTHWEST.
BEACH FORECAST
LIFE-THREATENING RIP CURRENTS WILL CONTINUE ACROSS THE NORTH-FACING
BEACHES OF THE ISLANDS THROUGH THE REST OF THE WEEK DUE TO PULSES OF
LONG PERIOD NORTHERLY SWELLS. A LARGER, NORTHWESTERLY SWELL WILL
ARRIVE ON THURSDAY, BUILDING SEAS BETWEEN 8 AND 12 FEET AT 13 TO 15
SECONDS. THIS WILL LIKELY RESULT IN COASTAL FLOOD AND HIGH SURF
ADVISORY CONDITIONS, PARTICULARLY FROM THE WEST/NORTHWEST TO
NORTHEAST COAST OF PUERTO RICO FROM THURSDAY THROUGH FRIDAY.
THEREFORE, A COASTAL FLOOD ADVISORY AND A HIGH SURF ADVISORY ARE NOW
IN EFFECT, STARTING ON THURSDAY MORNING AND CONTINUING THROUGH AT
LEAST FRIDAY. FOR THE NORTHERN USVI AND CULEBRA, A HIGH SURF
ADVISORY AND A HIGH RIP CURRENT RISK ARE IN EFFECT. FOR THE
SOUTHWEST COAST OF PUERTO RICO, PARTICULARLY FOR THE WEST FACING
BEACHES, A HIGH RIP CURRENT RISK IS IN EFFECT.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HIGH RIP CURRENT RISK THROUGH LATE FRIDAY NIGHT FOR PRZ001-002-
005-008-012.
COASTAL FLOOD ADVISORY FROM 6 AM THURSDAY TO 6 AM AST FRIDAY FOR
PRZ001-002-005-008-010.
HIGH SURF ADVISORY FROM 6 AM THURSDAY TO 6 PM AST FRIDAY FOR
PRZ001-002-005-008-010-012.
HIGH RIP CURRENT RISK FROM THURSDAY MORNING THROUGH LATE FRIDAY
NIGHT FOR PRZ010-011.
VI...HIGH RIP CURRENT RISK THROUGH LATE FRIDAY NIGHT FOR VIZ001.
HIGH SURF ADVISORY FROM 6 AM THURSDAY TO 6 PM AST FRIDAY FOR
VIZ001.
HIGH RIP CURRENT RISK UNTIL 6 PM AST THIS EVENING FOR VIZ002.
AM...SMALL CRAFT ADVISORY UNTIL 6 PM AST FRIDAY FOR AMZ711-712-741.
SMALL CRAFT ADVISORY FROM 6 AM THURSDAY TO 6 PM AST FRIDAY FOR
AMZ716-742.
SMALL CRAFT ADVISORY FROM 6 PM THURSDAY TO 6 PM AST FRIDAY FOR
AMZ745.
SHORT TERM...YZR/MMC
LONG TERM...GRS
AVIATION...YZR/DSR
MARINE/BEACH FORECAST...DSR
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