720
FXCA62 TJSJ 130618
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
218 AM AST FRI MAR 13 2026
...NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST, FIRE WEATHER...
KEY MESSAGES
ISSUED AT 158 AM AST FRI MAR 13 2026
* FLOODING IN URBAN AREAS, ON ROADS, AND ALONG SMALL STREAMS IS
POSSIBLE THIS MORNING OVER EASTERN PR AND USVI AND THEN THIS
AFTERNOON ACROSS THE INTERIOR AND WESTERN PUERTO RICO.
* A DRIER TREND IS EXPECTED BY LATE FRIDAY INTO SATURDAY,
ALTHOUGH LOCALIZED SHOWERS MAY STILL DEVELOP DURING THE
AFTERNOON HOURS DUE TO LOCAL EFFECTS.
* INCREASING WINDS ARE EXPECTED ON SUNDAY INTO NEXT WEEK, LEADING
TO HAZARDOUS MARINE AND BEACH CONDITIONS.
* ACROSS THE U.S. VIRGIN ISLANDS, OCCASIONAL PASSING TRADE-WIND
SHOWERS WILL CONTINUE, WITH A DRYING TREND EXPECTED BY LATE
FRIDAY INTO SATURDAY.
SHORT TERM(TODAY THROUGH SUNDAY)
ISSUED AT 158 AM AST FRI MAR 13 2026
DURING THE OVERNIGHT HOURS, CLEAR SKIES PREVAILED ACROSS WESTERN
PUERTO RICO, WHILE EASTERN PUERTO RICO, VIEQUES, CULEBRA, AND THE U.S.
VIRGIN ISLANDS OBSERVED PARTLY CLOUDY SKIES AS A PATCH OF
MOISTURE FILTERED ACROSS THE REGION, INCREASING THE FREQUENCY OF
SHOWERS. NEVERTHELESS, RAINFALL ACCUMULATIONS RANGED FROM 0.10 TO
0.30 BY 2 AM. TEMPERATURES ALONG COASTAL AREAS RANGED FROM THE
UPPER 60S TO THE MID-70S, WHILE INTERIOR AND MOUNTAINOUS LOCATIONS
COOLED INTO THE 60S, SIMILAR TO PREVIOUS NIGHTS. WINDS REMAINED
LIGHT AND VARIABLE.
TODAY, AN ANOTHER SURGE OF MOISTURE WILL CONTINUE TO MOVE ACROSS
EASTERN PUERTO RICO DURING THE MORNING HOURS, PRODUCING PERIODS OF
SHOWERS. THIS INCREASE IN MOISTURE, COMBINED WITH DAYTIME
HEATING, WILL PROMOTE THE DEVELOPMENT OF AFTERNOON CONVECTION
ACROSS THE INTERIOR AND WESTERN PUERTO RICO, WITH PERIODS OF
MODERATE RAINFALL, RAISING THE POTENTIAL FOR PONDING OF WATER ON
ROADS AND IN POORLY DRAINED AND URBAN AREAS. LATE TODAY INTO
SATURDAY, PRECIPITABLE WATER VALUES ARE FORECAST TO DECREASE TO
NEAR OR BELOW THE 25TH PERCENTILE FOR THIS TIME OF YEAR,
ACCOMPANIED BY LOWER MID-LEVEL RELATIVE HUMIDITY AND WARMING
TEMPERATURES AT 500 MB LEVEL, RESULTING IN A MORE STABLE
ATMOSPHERIC PROFILE AND IMPROVING WEATHER CONDITIONS AS A DRIER
AIR MASS PREVAILS ACROSS THE REGION. THEREFORE, EXPECT MOSTLY
SUNNY SKIES WITH ONLY BRIEF PASSING SHOWERS ACROSS WINDWARD AREAS,
MAINLY DURING THE MORNING HOURS, MAINLY ON SATURDAY. AS THE DAY
PROGRESSES ON SATURDAY, EASTERLY TRADE WINDS WILL STRENGTHEN AS A
HIGH- PRESSURE SYSTEM BUILDS OVER THE WESTERN ATLANTIC, PROMOTING
BREEZY CONDITIONS.
ON SUNDAY, PRECIPITABLE WATER VALUES ARE EXPECTED TO RETURN TO
NEAR-NORMAL LEVELS AS ANOTHER PATCH OF MOISTURE APPROACHES THE
REGION. HOWEVER, INSTABILITY IS NOT ANTICIPATED. AS A RESULT,
TYPICAL TRADE-WIND SHOWERS WILL AFFECT EASTERN PUERTO RICO AND THE
U.S. VIRGIN ISLANDS DURING THE OVERNIGHT AND MORNING HOURS,
FOLLOWED BY ISOLATED AFTERNOON ACTIVITY ACROSS WESTERN PUERTO
RICO. OVERALL RAINFALL ACCUMULATIONS ARE NOT EXPECTED TO BE
SIGNIFICANT, AS BREEZY TO LOCALLY WINDY CONDITIONS WILL PREVAIL,
AND CONDITIONS WILL REMAIN SEASONABLE.
LONG TERM(MONDAY THROUGH FRIDAY)
ISSUED AT 158 AM AST FRI MAR 13 2026
A BROAD SURFACE HIGH-PRESSURE SYSTEM OVER THE WESTERN ATLANTIC WILL
STRENGTHEN BY EARLY NEXT WEEK, TIGHTENING THE PRESSURE GRADIENT
ACROSS THE NORTHEASTERN CARIBBEAN AND PROMOTING A STEADY INCREASE IN
EASTERLY TO EAST-SOUTHEASTERLY LOW-LEVEL FLOW BEGINNING MONDAY AND
PERSISTING THROUGH MUCH OF THE WORKWEEK. MODEL GUIDANCE INDICATES
925 MB WINDS INCREASING WELL ABOVE CLIMATOLOGICAL VALUES, PEAKING
NEAR OR ABOVE TWO STANDARD DEVIATIONS ABOVE NORMAL ON MONDAY. AS A
RESULT, BREEZY TO LOCALLY WINDY CONDITIONS ARE EXPECTED,
PARTICULARLY ACROSS COASTAL AREAS OF PUERTO RICO, CULEBRA, VIEQUES,
AND THE U.S. VIRGIN ISLANDS, WHERE A LIMITED TO LOCALLY ELEVATED
WIND THREAT MAY DEVELOP AND UNSECURED OUTDOOR ITEMS COULD BE BLOWN
AROUND OR DAMAGED. ALTHOUGH THE PRESSURE GRADIENT IS EXPECTED TO
RELAX SLIGHTLY AFTER MONDAY, WINDS WILL LIKELY REMAIN ABOVE NORMAL
THROUGH THE REMAINDER OF THE FORECAST PERIOD.
MID-LEVEL CONDITIONS WILL REMAIN GENERALLY STABLE THROUGH THE
FORECAST PERIOD. MODEL GUIDANCE CONTINUES TO SHOW 700–500 MB LAPSE
RATES BELOW NORMAL TO NEAR THE LOWER END OF CLIMATOLOGICAL VALUES,
WHILE 500 MB TEMPERATURES REMAIN NEAR CLIMATOLOGICAL NORMALS.
ALTHOUGH A POLAR TROUGH AND ITS ASSOCIATED FRONTAL BOUNDARY ARE
FORECAST TO MOVE OFF THE EASTERN SEABOARD EARLY NEXT WEEK, AND AN
UPPER-LEVEL TROUGH MAY DEVELOP NORTHEAST OF THE FORECAST AREA TOWARD
THE END OF THE PERIOD, THE LOCAL AREA WILL REMAIN LARGELY REMOVED
FROM THE STRONGEST DYNAMICAL FORCING. AS A RESULT, MOST OF THE
REGION WILL CONTINUE TO EXPERIENCE MARGINALLY STABLE CONDITIONS,
LIMITING DEEP CONVECTIVE DEVELOPMENT AND FAVORING MAINLY SHALLOW
TRADE WIND SHOWERS. RELATIVE HUMIDITY VALUES IN THE MID-LEVELS WILL
ALSO REMAIN MODEST, FURTHER SUPPORTING A GENERALLY STABLE PATTERN.
MOISTURE LEVELS WILL REMAIN NEAR CLIMATOLOGICAL NORMALS THROUGH MOST
OF THE PERIOD, WITH PRECIPITABLE WATER GENERALLY FLUCTUATING BETWEEN
AROUND 1.2 AND 1.5 INCHES. PATCHES OF SHALLOW MOISTURE EMBEDDED
WITHIN THE TRADE WIND FLOW WILL PERIODICALLY MOVE ACROSS THE REGION,
RESULTING IN BRIEF PASSING SHOWERS ACROSS WINDWARD SECTORS,
PARTICULARLY DURING THE NIGHTTIME AND MORNING HOURS ACROSS EASTERN
PUERTO RICO AND THE U.S. VIRGIN ISLANDS. DURING THE AFTERNOONS,
DIURNAL HEATING COMBINED WITH LOCAL EFFECTS MAY SUPPORT THE
DEVELOPMENT OF ISOLATED TO SCATTERED SHOWERS ACROSS INTERIOR AND
WESTERN PORTIONS OF PUERTO RICO. HOWEVER, THE FASTER STEERING WIND
FLOW WILL LIMIT THE RESIDENCE TIME OF SHOWERS AND KEEP RAINFALL
ACCUMULATIONS GENERALLY LOW. DESPITE THIS, PONDING OF WATER ON ROADS
AND IN POORLY DRAINED AREAS, ALONG WITH BRIEF REDUCTIONS IN
VISIBILITY, CAN STILL OCCUR IN AREAS EXPERIENCING THE HEAVIEST
SHOWERS.
AVIATION
(06Z TAFS)
ISSUED AT 158 AM AST FRI MAR 13 2026
ALL TAF SITES SHOULD EXPERIENCE VFR CONDS WILL PREVAIL. VCSH
POSSIBLE AT TJSJ, TIST, AND TISX THROUGH 13/14Z. HOWEVER, -SHRA
COULD CAUSE PERIODS OF MVFR CONDT MAINLY BY 14/17Z AT
TJSJ/TJBQ/TJPS. EASTERLY WINDS BTWN 10-15 KT WITH GUSTS UP TO 20
KT AND SEA BREEZE VARIATIONS AFT 13/14Z.
MARINE
ISSUED AT 158 AM AST FRI MAR 13 2026
UNDER A WEAKENING PRESSURE GRADIENT ACROSS THE NORTHEASTERN
CARIBBEAN, WINDS WILL REMAIN GENTLE TO MODERATE FROM THE EAST TO
NORTHEAST WITH SEAS OF 3 TO 5 FEET. HOWEVER, A HIGH PRESSURE WILL
BUILD ACROSS THE NORTHWESTERN ATLANTIC LATE SATURDAY INTO EARLY NEXT
WEEK WILL TIGHTEN THE LOCAL PRESSURE GRADIENT AND PROMOTE INCREASED
WIND SPEEDS. FRESH TO STRONG TRADE WINDS ARE EXPECTED BY TOMORROW,
SATURDAY, NIGHT INTO EARLY NEXT WEEK, AND WILL RESULT IN ROUGH AND
CHOPPY SEAS AND OVERALL DETERIORATED MARINE CONDITIONS. SMALL CRAFT
ADVISORIES WILL LIKELY BE ISSUED LATER ON FROM LATE IN THE WEEKEND
INTO EARLY NEXT WEEK, WITH SEAS FORECAST TO BUILD TO AROUND 6 TO 8
FEET.
BEACH FORECAST
ISSUED AT 158 AM AST FRI MAR 13 2026
TODAY, A MODERATE RISK OF RIP CURRENTS (LIFE-THREATENING RIP
CURRENTS ARE POSSIBLE IN THE SURF ZONE) WILL PERSIST FOR NORTHERN
BEACHES OF PUERTO RICO (FROM AGUADILLA TO FAJARDO), CULEBRA, AND
NORTHERN AND EASTERN BEACHES OF ST. CROIX. BEACHGOERS SHOULD
CONTINUE TO EXERCISE CAUTION. A LOW RISK OF RIP CURRENTS WILL BE
PRESENT ACROSS OTHER EXPOSED BEACHES OF THE ISLANDS. EVEN IF THE
RISK IS LOW, LIFE-THREATENING RIP CURRENTS OFTEN OCCUR IN THE
VICINITY OF GROINS, JETTIES, REEFS, AND PIERS.
A SIMILAR PATTERN WILL PERSIST THROUGH TOMORROW, SATURDAY, NIGHT. ON
SUNDAY THE MODERATE RISK WILL START TO EXPAND TO OTHER BEACHES AS
BREEZY CONDITIONS START TO DEVELOP, AND BY MONDAY ONWARDS, A HIGH
RIP CURRENT RISK WILL LIKELY BE IN EFFECT, ALONG WITH BREEZY TO
WINDY CONDITIONS. BEACHGOERS SHOULD CONTINUE MONITORING THE
FORECAST FOR ANY UPDATES. FOR ADDITIONAL INFORMATION, PLEASE VISIT:
WEATHER.GOV/BEACH/SJU.
FIRE WEATHER
ISSUED AT 158 AM AST FRI MAR 13 2026
ONCE AGAIN, THE RISK FOR FIRE WEATHER TREATS REMAINS LOW TODAY.
WINDS WILL REMAIN LIGHT TO MODERATE AND RH VALUES ARE EXPECTED
TO REMAIN ABOVE CRITERIA DUE TO THE ARRIVAL OF ANOTHER PATCH OF
MOISTURE ACROSS THE AREA. AT THIS TIME AN RFD WILL NOT BE ISSUED,
BUT WE ENCOURAGE PARTNERS TO CONTINUE MONITORING CONDITIONS IN THE
COMING DAYS, PARTICULARLY ON SATURDAY AS A DRIER AIRMASS IS
EXPECTED TO ARRIVE.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
SHORT TERM/AVIATION/FIRE WEATHER...MMC
LONG TERM...CVB
MARINE/BEACH FORECAST...MRR
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