452
FXCA62 TJSJ 111803
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
203 PM AST THU SEP 11 2025
KEY MESSAGES
* HOT TEMPERATURES ARE EXPECTED TO CONTINUE OVER THE NEXT SEVERAL
DAYS ACROSS THE LOCAL ISLANDS.
* AFTERNOON SHOWERS AND THUNDERSTORMS ARE LIKELY EACH DAY,
ESPECIALLY ACROSS PUERTO RICO’S INTERIOR AND NORTHWESTERN AREAS.
THE CONVECTIVE ACTIVITY MAY BRING FLOODING RAINFALL AND
FREQUENT LIGHTNING.
* IN THE U.S. VIRGIN ISLANDS, EXPECT MOSTLY SUNNY SKIES WITH WARM TO
HOT TEMPERATURES AND OCCASIONAL PASSING SHOWERS.
* A TROPICAL WAVE IS FORECAST TO INCREASE THE CHANCE OF SHOWERS
AND THUNDERSTORMS BY EARLY NEXT WEEK.
SHORT TERM...REST OF TODAY THROUGH SATURDAY
STABLE WEATHER CONDITIONS PREVAILED ACROSS THE ISLANDS DURING MOST
OF THE MORNING HOURS, WITH MOSTLY CLEAR SKIES AND SOME BRIEF PASSING
SHOWERS ACROSS THE COASTAL AREAS OF ST. THOMAS. BY 11 AM, SATELLITE
AND DOPPLER RADAR IMAGERY INDICATED CLOUDINESS DEVELOPING NEAR THE
EASTERN PORTIONS OF PUERTO RICO AND THE CORDILLERA CENTRAL,
RESULTING IN LIMITED SHOWER ACTIVITY ACROSS THOSE AREAS. MAXIMUM
TEMPERATURES AND HEAT INDICES BETWEEN 110 AND 113 DEGREES WERE
OBSERVED ALONG THE NORTH-CENTRAL AND SOUTHERN SECTIONS.
FOR THE REST OF THE AFTERNOON INTO THE EVENING, VARIABLE WEATHER
CONDITIONS WILL PERSIST, WITH PERIODS OF LIGHT TO MODERATE SHOWERS
ASSOCIATED WITH A SURFACE PERTURBATION JUST NORTH OF THE FORECAST
AREA. THIS INDUCED SURFACE TROUGH AND THE ACCOMPANYING UPPER-LEVEL
TROUGH WILL GRADUALLY MOVE OUT OF THE REGION AS THEY TRACK
NORTHWESTWARD INTO THE NORTHWESTERN ATLANTIC. AS THIS FEATURE
EVOLVES, IT WILL WEAKEN THE PRESSURE GRADIENT, ALLOWING LIGHTER
WINDS TO DEVELOP BY TOMORROW MORNING. CONSEQUENTLY, LIGHTER WINDS
ARE EXPECTED THROUGH FRIDAY AND INTO SATURDAY, FAVORING SLOW-MOVING
SHOWERS THAT WILL ENHANCE RAINFALL ACCUMULATION WITH AFTERNOON
CONVECTION EACH DAY. ON FRIDAY, RESIDENTS CAN ANTICIPATE A SIMILAR
PATTERN: WARMER CONDITIONS, LIMITED SHOWERS IN THE MORNING, AND A
MORE ACTIVE AFTERNOON. BY SATURDAY, A SMALL PATCH OF DRIER AIR WILL
BRIEFLY MOVE IN, PROMOTING CLEARER SKIES ALOFT AND PARTLY CLOUDY
CONDITIONS BELOW. HOWEVER, ADDITIONAL MOISTURE WILL RETURN BY THE
AFTERNOON, FOCUSING SHOWER ACTIVITY ACROSS THE NORTHWESTERN
INTERIOR. ADDITIONALLY, 925 MB TEMPERATURE ANALYSES CONTINUE TO
SUGGEST AN ELEVATED TO SIGNIFICANT HEAT THREAT FOR THE REMAINDER OF
THE PERIOD. THIS THREAT WILL BE MOSTLY DUE TO THE PRESENCE OF
SUFFICIENT TROPICAL MOISTURE OVER THE ISLANDS THAT COMBINES WITH A
SOUTHEASTERLY WIND COMPONENT.
LONG TERM...SUNDAY THROUGH THURSDAY
PREV DISCUSSION
/ISSUED 257 AM AST THU SEP 11 2025/
A WET PATTERN IS ON THE WAY FOR THE ISLANDS. AN UPPER-LEVEL TROUGH
NORTHEAST OF THE REGION WILL BRING SHOWERS AND THUNDERSTORMS ON
SUNDAY. BY MONDAY, A TROPICAL WAVE WILL MOVE OVER THE ISLANDS,
BRINGING MORE ACTIVITY ACROSS PUERTO RICO AND THE U.S. VIRGIN
ISLANDS.
THE LATEST PRECIPITABLE WATER CONTENT GUIDANCE (PWAT) INDICATES
VALUES OF 1.90 TO 2.20 INCHES THROUGH LATE MONDAY. FOLLOWING THIS, A
MASS OF DRIER AIR WILL QUICKLY MOVE IN, BRINGING STABLE CONDITIONS
THROUGH THE MIDDLE OF THE WEEK. BY LATE TUESDAY AND INTO WEDNESDAY,
A SECOND TROPICAL WAVE WILL APPROACH THE U.S. VIRGIN ISLANDS AND
PUERTO RICO. THIS WAVE, COMBINED WITH MOISTURE AND INSTABILITY FROM
A NEARBY UPPER-LEVEL TROUGH, WILL RESULT IN PERIODS OF MODERATE TO
HEAVY SHOWERS AND THUNDERSTORMS ACROSS THE REGION. THE U.S. VIRGIN
ISLANDS CAN EXPECT SHOWERS AND FEW ISOLATED THUNDERSTORMS,
PARTICULARLY DURING THE MORNING HOURS. THEN, AFTERNOON CONVECTIVE
ACTIVITY IS EXPECTED ACROSS CENTRAL AND NORTHWESTERN PUERTO RICO
THROUGH THE EARLY EVENING HOURS. UNDER THESE CONDITIONS, THERE IS
A LIMITED TO ELEVATED RISK FOR URBAN AND SMALL STREAM FLOODING,
AS WELL AS LIGHTNING ACROSS THE ISLANDS.
THE 925 MB TEMPERATURE WILL REMAIN ABOVE-THAN-NORMAL THROUGHOUT
THE PERIOD. HIGHS WILL REMAIN IN THE UPPER 80S TO LOW 90S ALONG
THE COASTAL AND URBAN AREAS OF THE ISLANDS, TO THE LOW 80S IN THE
HIGHER ELEVATIONS. RESIDENTS AND VISITORS ARE ADVISED TO MONITOR
THE WEATHER CONDITIONS AND PLAN ACCORDINGLY IF HAVING OUTDOOR
ACTIVITIES UNDER SUN EXPOSURE.
AVIATION
(18Z TAFS)
VFR CONDITIONS WILL REMAIN FOR MOST OF THE PERIOD ACROSS ALL TAF
SITES. BRIEF MVFR CONDITIONS ARE FORECASTED FOR TJBQ AT AROUND
11/19Z TO 11/23Z DUE TO THE TSRA LOWERING THE CEILING AND VIS.
WINDS WILL CONTINUE FROM THE E AT 15 KNOTS WITH GUSTY WINDS NEAR
THE COASTAL AREA AND SHOWERS. WINDS WILL DIMINISH AT 11/23Z,
BECOMING LIGHTER FROM THE EAST TOMORROW AT AROUND 12/15Z. SHRA &
TSRA ARE FORECAST AGAIN FOR TJSJ, TJBQ & TJPS TOMORROW AT 12/16Z.
MARINE
A SURFACE HIGH PRESSURE OVER THE CENTRAL ATLANTIC AND A FRONT OVER
THE WESTERN ATLANTIC WILL CONTINUE TO SUPPORT LIGHT TO MODERATE
EAST TO SOUTHEAST WINDS THROUGH THE WEEKEND. SEAS WILL REMAIN
AROUND 2 TO 4 FEET ACROSS MOST LOCAL WATERS AND THE CARIBBEAN
PASSAGES. BY LATE IN THE WEEKEND INTO EARLY NEXT WEEK, WINDS ARE
EXPECTED TO INCREASE TO MODERATE TO LOCALLY FRESH LEVELS, WITH A
BETTER CHANCE OF SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS THE
REGION.
BEACH FORECAST
A MODERATE RISK OF RIP CURRENTS CONTINUES THROUGH THIS EVENING FOR
NORTHERN AND EAST-FACING BEACHES OF PUERTO RICO AND ST. CROIX. THE
RISK IS EXPECTED TO DECREASE TO LOW LEVELS TONIGHT AND CONTINUE
INTO THE WEEKEND. HOWEVER, EVEN WITH A LOW RISK, LIFE-THREATENING
RIP CURRENTS CAN STILL OCCUR NEAR GROINS, JETTIES, REEFS, AND
PIERS, SO BEACHGOERS ARE ADVISED TO EXERCISE CAUTION AT ALL TIMES.
THE RIP CURRENT RISK IS FORECAST TO INCREASE TO MODERATE AGAIN BY
EARLY NEXT WEEK. ADDITIONAL HAZARDS INCLUDE ISOLATED AFTERNOON
THUNDERSTORMS AND AN ELEVATED TO SIGNIFICANT HEAT RISK. REMEMBER:
IF YOU HEAR THUNDER, SEEK SHELTER INDOORS IMMEDIATELY, AND BE SURE
TO STAY WELL HYDRATED.
SJU WATCHES/WARNINGS/ADVISORIES
PR...EXTREME HEAT WARNING UNTIL 4 PM AST THIS AFTERNOON FOR
PRZ001>005-007-008-010-011.
HEAT ADVISORY UNTIL 4 PM AST THIS AFTERNOON FOR PRZ012-013.
VI...HEAT ADVISORY UNTIL 4 PM AST THIS AFTERNOON FOR VIZ001-002.
AM...NONE.
SHORT TERM/AVIATION...LIS
LONG TERM...GRS
MARINE/BEACH FORECAST...YZR
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page