339
FXCA62 TJSJ 051602
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1202 PM AST WED MAR 5 2025
UPDATE
..HIGH RIP CURRENT RISK NOW IN EFFECT FOR THE NORTH COAST OF PR
LOCALLY INDUCED SHOWERS ARE DEVELOPING FROM COAMO/AIBONITO
WESTWARD TO AGUADA/CABO ROJO. STREAMERS WERE ALREADY DEVELOPING
OVER THE USVI WITH SHOWERS STREAMING WESTWARD OVER THE COASTAL
WATERS. THE FORECAST REMAINS ON TRACK, AND HEAVY SHOWERS ARE
EXPECTED TO DEVELOP ALONG PORTIONS OF THE CORDILLERA AND WESTERN
PR. ALSO, SHOWERS WITH POSSIBLE ISO THUNDERSTORMS CAN DEVELOP OVER
EL YUNQUE AND DOWNWIND INTO THE SAN JUAN METRO AREA AND NEARBY
MUNICIPALITIES.
AVIATION
(12Z TAFS)
VFR EARLY IN THE FCST CYCLE. SHRA/TSRA EXPECTED TO DEVELOP OVER
THE INTERIOR AND WESTERN PR BTW 05/16Z-23Z. THE 05/12Z TJSJ
SOUNDING INDICATED EAST WINDS UP TO 12 KT BLO FL100.
MARINE
OFFSHORE BUOY 41043 INDICATED A NORTH SWELL AROUND 7 FEET AT 10/11
SECONDS DURING THE EARLY MORNING HOURS AND THIS ENERGY IS REACHING
THE LOCAL ATLANTIC WATERS AND CARIBBEAN PASSAGES. THE RINCON AND
SAN JUAN BUOYS INDICATED 5 FT SEAS AT 10/11 SECONDS. ALTHOUGH, SCA
ARE NOT NEEDED, SMALL CRAFT SHOULD CONTINUE TO EXERCISE CAUTION
DUE TO SEAS UP 6 FEET. LIGHT EAST WINDS WITH SEA BREEZE INFLUENCE
ACROSS COASTAL AREAS WILL CONTINUE FOR THE REST OF THE DAY.
BEACH FORECAST
HIGH RIP CURRENT RISK NOW IN EFFECT THROUGH THIS EVENING FOR THE
NORTHERN BEACHES OF PUERTO RICO FROM FAJARDO TO AGUADILLA. A
NORTHERLY SWELL IS GRADUALLY BUILDING ACROSS THE ATLANTIC WATERS,
AND LIFE-THREATENING RIP CURRENTS ARE LIKELY TO DEVELOP ACROSS THE
NORTHERN COAST OF PR AT LEAST THROUGH THIS EVENING.
PREV DISCUSSION
/ISSUED ISSUED BY NATIONAL WEATHER SERVICE MIAMI FL/
SYNOPSIS...
AN UNSTABLE WEATHER PATTERN IS EXPECTED TODAY THROUGH THE END OF THE WORKWEEK,
AS INSTABILITY AND MOISTURE PERSIST OVER THE REGION. MORNING CONDITIONS
WILL BE VARIABLE, FOLLOWED BY AFTERNOON CONVECTION DEVELOPING ALONG
THE MOUNTAINSIDES AND IN THE NORTHWESTERN QUADRANT. THERE IS AN
ELEVATED THREAT OF URBAN FLOODING, PARTICULARLY IN AREAS THAT HAVE
EXPERIENCED RECENT RAINFALL.
SHORT TERM...TODAY THROUGH FRIDAY...
AS EXPECTED, THE MID-TO UPPER-LEVEL TROUGH PERSISTED OVER THE LOCAL AREA,
ALTHOUGH THE MOST ACTIVE REGION REMAINED WELL NORTH OF THE NORTHEASTERN
CARIBBEAN. STILL, THE LAND BREEZE COMBINED WITH SUFFICIENT LOW-LEVEL
MOISTURE AND INSTABILITY ALOFT GENERATED A LINE OF HEAVY SHOWERS
JUST OFFSHORE OF NORTHERN COASTAL PUERTO RICO. THESE SHOWERS PERSISTED
FOR MOST OF THE NIGHT, OCCASIONALLY BRUSHING PORTIONS OF THE COAST.
MARINE WEATHER STATEMENTS WERE ISSUED THROUGHOUT THE NIGHT FOR THIS
AREA. SIMILAR ACTIVITY IS EXPECTED TO CONTINUE OVER THE NEXT FEW HOURS,
WITH SOME AREAS ALONG NORTHERN COASTAL PUERTO RICO LIKELY TO SEE AN
INCREASE IN SHOWERS AS THE LAND BREEZE SUBSIDES AND SOME OF THESE
SHOWERS MOVE INLAND.
THE STRONGEST PHASE OF THE TROUGH WILL OCCUR TODAY, PROMOTING LOW 250 MB
HEIGHT FIELDS AND COOL 500 MB TEMPERATURES. HOWEVER, AS MENTIONED EARLIER,
ITS MOST ACTIVE AREA WILL REMAIN NORTH OF THE CARIBBEAN. AT LOW LEVELS,
AN INDUCED SURFACE TROUGH WILL CONTINUE MOVING ACROSS THE FORECAST
AREA TODAY, MAINTAINING ABOVE-NORMAL MOISTURE CONTENT. THIS PATTERN,
COMBINED WITH DIURNAL HEATING AND SEA BREEZE CONVERGENCE, WILL
LEAD TO ANOTHER ACTIVE AFTERNOON. SHOWERS AND ISOLATED THUNDERSTORMS
ARE EXPECTED TO DEVELOP OVER INTERIOR PUERTO RICO BY EARLY AFTERNOON,
PROPAGATING OUTWARD TOWARD COASTAL AREAS THROUGH THE EVENING.
LATER TONIGHT, SHOWER ACTIVITY IS EXPECTED TO DEVELOP OVER REGIONAL
WATERS, WITH SOME SHOWERS POTENTIALLY AFFECTING COASTAL AREAS OF
PUERTO RICO AND THE U.S. VIRGIN ISLANDS, PARTICULARLY ST. THOMAS.
HOWEVER, SIGNIFICANT RAINFALL ACCUMULATIONS ARE NOT ANTICIPATED
DURING THIS PERIOD.
A SIMILAR WEATHER PATTERN IS EXPECTED ON THURSDAY AND FRIDAY, WITH
DYNAMICS ALOFT GRADUALLY BECOMING LESS UNSTABLE AS THE TROUGH
MOVES EASTWARD AND WEAKENS, THOUGH SOME MARGINAL INSTABILITY WILL
LINGER THROUGH FRIDAY. MEANWHILE, MOISTURE CONTENT WILL SLIGHTLY
DECREASE TO NEAR NORMAL LEVELS. HOWEVER, A FRONTAL BOUNDARY
NORTHWEST OF PUERTO RICO WILL APPROACH THE NORTHEASTERN CARIBBEAN.
AS IT NEARS, WINDS WILL SHIFT MORE SOUTHEASTERLY ON THURSDAY AND
SOUTHERLY BY FRIDAY, WHILE WIND SPEEDS WILL PLUMMET AS A COL
SETTLES JUST NORTH OF PUERTO RICO. ALTHOUGH ABOVE-NORMAL MOISTURE
AND INSTABILITY ARE NOT EXPECTED FOR THE REMAINDER OF THE SHORT-
TERM FORECAST, SUFFICIENT MOISTURE WILL STILL COMBINE WITH SURFACE
HEATING DURING THE AFTERNOON HOURS. ADDITIONALLY, WEAK STEERING
WINDS WILL PROLONG THE RESIDENCE TIME OF SHOWERS AND ANY THUNDERSTORMS
THAT DEVELOP, ENHANCING RAINFALL ACCUMULATIONS. AS A RESULT, EXPECT
A LIMITED TO ELEVATED FLOODING RISK EACH AFTERNOON, MOSTLY ACROSS
INTERIOR PUERTO RICO, POTENTIALLY LEADING TO URBAN AND SMALL-STREAM
FLOODING. QUICK RIVER RISES AND WATER SURGES ARE ALSO ANTICIPATED
IN SOME RIVERS.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
MID- TO UPPER-LEVEL ATMOSPHERIC STABILITY WILL REMAIN IN PLACE FROM
SATURDAY THROUGH WEDNESDAY AS A MID-LEVEL RIDGE BUILDS OVER THE WESTERN
ATLANTIC, EXTENDING INTO THE CARIBBEAN. THIS FEATURE WILL SUPPORT
WARMER-THAN-NORMAL 500 MB TEMPERATURES, SUPPRESSING DEEP CONVECTIVE
DEVELOPMENT ACROSS THE REGION.
A BROAD SURFACE PRESSURE SYSTEM WILL DOMINATE THE REGION THROUGH THE
WEEKEND, MAINTAINING A NORTHEASTERLY WIND FLOW UNTIL SUNDAY MORNING.
UNDER THIS WIND FLOW, MOSTLY SHALLOW PATCHES OF MOISTURE WITH
PRECIPITABLE WATER (PWAT) VALUES BELOW CLIMATOLOGICAL NORMALS
WILL PERSIST. HOWEVER, SURFACE HEATING AND LOCAL EFFECTS WILL
CONTRIBUTE TO SHOWER DEVELOPMENT SHIFTING TOWARD THE SOUTHWESTERN
QUADRANT OF PUERTO RICO. BY LATE SUNDAY, WINDS WILL GRADUALLY
SHIFT FROM THE EAST-SOUTHEAST AS A SURFACE HIGH PRESSURE MOVES
WESTWARD INTO THE CENTRAL ATLANTIC. ACCORDING TO THE MODEL GLOBAL
GUIDANCE, PRECIPITABLE WATER VALUES WOULD REMAIN NEAR OR JUST
BELOW NORMAL. AS A RESULT, SHOWER ACTIVITY WILL FOLLOW A SEASONAL
PATTERN, WITH ISOLATED TO SCATTERED SHOWERS MOVING ACROSS WINDWARD
COASTAL AREAS DURING THE NIGHT AND EARLY MORNING HOURS, FOLLOWED
BY LOCALIZED SHALLOW CONVECTION DEVELOPING ACROSS WESTERN AND SOME
INTERIOR SECTIONS OF PUERTO RICO IN THE AFTERNOONS. GIVEN THE
STABLE CONDITIONS AND LIMITED MOISTURE AVAILABILITY, SIGNIFICANT
RAINFALL ACCUMULATIONS OR WIDESPREAD FLOODING CONCERNS ARE NOT
ANTICIPATED.
BY EARLY NEXT WORKWEEK, DRIER AIR WILL GRADUALLY FILTER INTO THE
REGION. TUESDAY AND WEDNESDAY ARE EXPECTED TO BE THE DRIEST DAYS
UNDER THE INFLUENCE OF THE MID-LEVEL RIDGE AND LIMITED MOISTURE
AVAILABILITY. OVERALL, A QUIET WEATHER PATTERN IS EXPECTED THROUGH
THE LONG-TERM PERIOD, WITH LIMITED SHOWER ACTIVITY AND STABLE
ATMOSPHERIC CONDITIONS DOMINATING THE LOCAL FORECAST.
AVIATION...
(06Z TAFS)
VFR CONDS WILL PREVAIL EXCEPT FOR MVFR IN PASSING SHRA, PARTICULARLY
FOR TJSJ TAF SITE. EXPECT AREAS OF +SHRA/TSRA TO BRING MVFR/IFR
CONDS TO WRN AND INTERIOR PR WITH MTN OBSCURATIONS AFT 05/17Z,
SHRA WILL DIMINISH AFT 05/23Z, BUT SCT SHRA WILL CONT OVR ERN PR.
SFC WINDS E 10-15 KTS WITH HIR GUSTS IN SEA BREEZES. WINDS BCMG
LAND BREEZES AT LESS THAN 10 KTS AFT 06/00Z.
MARINE...
A FRONTAL BOUNDARY APPROACHING FROM THE WESTERN ATLANTIC WILL
GRADUALLY WEAKEN THE PRESSURE GRADIENT ASSOCIATED WITH THE BROAD
SURFACE HIGH PRESSURE EXTENDING FROM THE EASTERN TO CENTRAL
ATLANTIC, LEAVING MOSTLY LIGHT TO MODERATE EASTERLY WINDS. AN
UPPER-LEVEL TROUGH AND THE ASSOCIATED INSTABILITY WILL CONTINUE TO
RESULT IN SHOWERS AND SOME ISOLATED THUNDERSTORMS OVER THE
REGIONAL WATERS THROUGHOUT THE DAY. ADDITIONALLY, A LONG-PERIOD
NORTHWESTERLY SWELL IS EXPECTED TO ARRIVE THIS WEEKEND, LIKELY
CREATING HAZARDOUS MARINE CONDITIONS ACROSS THE ATLANTIC WATERS
AND NORTHERN LOCAL PASSAGES.
BEACH FORECAST...
A MODERATE RISK OF RIP CURRENTS WILL PERSIST ALONG THE NORTHERN
COASTAL AREAS OF PUERTO RICO DUE TO A BRIEF AND WEAK NORTHERLY
SWELL. BREAKING WAVES ARE EXPECTED TO REACH UP TO 5 FEET ALONG
NORTHERN AREAS, WITH LOWER HEIGHTS ACROSS THE REST OF THE COASTAL
SECTIONS OF THE ISLANDS.
COASTAL CONDITIONS ARE EXPECTED TO DETERIORATE OVER THE WEEKEND
AS ANOTHER NORTHERLY SWELL ARRIVES, INCREASING BREAKING WAVES
ALONG THE NORTHERN SECTIONS OF THE ISLANDS.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HIGH RIP CURRENT RISK UNTIL 6 PM AST THIS EVENING FOR PRZ001-002-
005-008.
VI...NONE.
AM...NONE.
SHORT TERM...DS
LONG TERM....99
AVIATION...DS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page