303
FXCA62 TJSJ 210650
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
250 AM AST SUN JUN 21 2026
...NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST, FIRE WEATHER...
KEY MESSAGES
ISSUED AT 250 AM AST SUN JUN 21 2026
* FATHER'S DAY IS EXPECTED TO BRING THE MOST ACTIVE WEATHER OF THE
FORECAST PERIOD AS A TROPICAL WAVE MOVES ACROSS THE REGION.
PERIODS OF HEAVY TO TORRENTIAL RAINFALL, THUNDERSTORMS, URBAN
AND SMALL-STREAM FLOODING, AND ISOLATED FLASH FLOODING ARE
POSSIBLE ACROSS PORTIONS OF PUERTO RICO AND THE U.S. VIRGIN
ISLANDS.
* MODERATE CONCENTRATIONS OF SAHARAN DUST WILL CONTINUE TO AFFECT
THE REGION EARLY THIS WEEK AND POSSIBLY THE SECOND PART OF THE
WEEK, RESULTING IN HAZY SKIES, REDUCED VISIBILITY, AND DEGRADED
AIR QUALITY, PARTICULARLY FOR SENSITIVE GROUPS.
* DANGEROUS HEAT INDEX VALUES WILL CONTINUE EACH AFTERNOON,
ESPECIALLY BETWEEN 10 AM AND 4 PM, AS HOT TEMPERATURES COMBINE
WITH TROPICAL MOISTURE. HEAT-RELATED ILLNESSES ARE POSSIBLE
WITHOUT ADEQUATE HYDRATION, COOLING, AND FREQUENT BREAKS FROM
THE HEAT.
* ANOTHER TROPICAL WAVE MAY APPROACH THE REGION BY THE MIDDLE OF
THE WEEK, BRINGING AN ADDITIONAL CHANCE FOR SHOWERS AND
THUNDERSTORMS. FORECAST DETAILS WILL CONTINUE TO BE REFINED AS
CONFIDENCE INCREASES.
* LIFE-THREATENING RIP CURRENTS WILL REMAIN POSSIBLE AT EXPOSED
BEACHES THROUGH MUCH OF THE WEEK DUE TO PERSISTENT MODERATE TO
LOCALLY BREEZY WINDS. BEACHGOERS SHOULD SWIM NEAR LIFEGUARDS,
HEED WARNING FLAGS, AND FOLLOW LOCAL BEACH SAFETY GUIDANCE.
SHORT TERM(TODAY THROUGH TUESDAY)
ISSUED AT 250 AM AST SUN JUN 21 2026
OVERNIGHT, WE HAD LITTLE OR NO RAIN AND WARM OVERNIGHT
TEMPERATURES AS A DRIER AIR MASS WITH MODERATE CONCENTRATIONS OF
SUSPENDED SAHARAN DUST PARTICLES LINGERED ACROSS PR AND THE USVI.
THE DOPPLER RADAR DETECTED SHOWERS APPROACHING THE ST CROIX
SURROUNDING WATERS, WITH SOME MOVING INLAND AS THE TROPICAL WAVE
FILTERS ACROSS THE REGION. ONCE AGAIN, AS WE WRITE THE DISCUSSION,
OVERNIGHT TEMPERATURES RANGED FROM THE MID- TO UPPER 70S TO THE
LOW 80S ALONG THE COAST, AND FROM THE MID- TO UPPER 60S TO THE LOW
70S ALONG THE MOUNTAINS. MOST WIND STATIONS REPORTED EAST TO
EAST-SOUTHEAST WINDS OF 5 TO 15 MPH, WITH FLUCTUATIONS DUE TO LAND
BREEZES. MEANWHILE, SOME STATIONS IN CULEBRA, ST. THOMAS, AND ST.
JOHN REPORTED EAST TO EAST-NORTHEAST WINDS AROUND 15, WITH HIGHER
GUSTS.
THE BEST CHANCE FOR WIDESPREAD AND BENEFICIAL RAINFALL WILL OCCUR
TODAY, FATHER'S DAY, AS A TROPICAL WAVE MOVES ACROSS PUERTO RICO
AND THE U.S. VIRGIN ISLANDS. ALTHOUGH THE WAVE IS EMBEDDED WITHIN
MODERATE TO HIGH CONCENTRATIONS OF SAHARAN DUST, AN ACCOMPANYING
SURGE OF MOISTURE WITH PRECIPITABLE WATER VALUES BETWEEN 1.85 AND
2.05 INCHES WILL SUPPORT PASSING SHOWERS ACROSS THE U.S. VIRGIN
ISLANDS AND EASTERN PUERTO RICO, FOLLOWED BY AFTERNOON CONVECTION
OVER WESTERN PUERTO RICO AND DOWNWIND OF EL YUNQUE. WHILE RAINFALL
WILL BE BENEFICIAL FOR AREAS EXPERIENCING ABNORMALLY DRY OR
MODERATE DROUGHT CONDITIONS, URBAN AND SMALL- STREAM FLOODING, AS
WELL AS ISOLATED FLASH FLOODING, REMAIN POSSIBLE WHERE PERSISTENT
DOWNPOURS AND THUNDERSTORMS DEVELOP.
BY MONDAY, THE TROPICAL WAVE WILL MOVE AWAY INTO THE CENTRAL
CARIBBEAN, WHILE MODERATE CONCENTRATIONS OF SAHARAN DUST CONTINUE
TO AFFECT THE REGION. HAZY SKIES, REDUCED VISIBILITY, AND POOR AIR
QUALITY ARE EXPECTED, PARTICULARLY FOR SENSITIVE GROUPS AND THOSE
WITH RESPIRATORY CONDITIONS. BREEZY EAST TO EAST-SOUTHEAST WINDS
WILL PERSIST AS A STRONG ATLANTIC HIGH PRESSURE SYSTEM MAINTAINS A
TIGHT LOCAL PRESSURE GRADIENT.
ON TUESDAY, A RELATIVELY STABLE AND DRIER AIR MASS WILL PREVAIL
ACROSS THE ISLANDS AS MID-LEVEL RIDGING STRENGTHENS AND AN
UPPER-LEVEL LOW LIFTS FARTHER NORTH OF THE REGION. PASSING TRADE-
WIND SHOWERS WILL CONTINUE TO AFFECT WINDWARD AND EASTERN AREAS,
WHILE LEEWARD SECTIONS EXPERIENCE MOSTLY FAIR WEATHER. SEASONABLY
WARM TEMPERATURES WILL PERSIST, WITH HIGHS REACHING THE UPPER 80S
TO LOW 90S ACROSS COASTAL AND URBAN LOCATIONS.
LONG TERM(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 250 AM AST SUN JUN 21 2026
A TROPICAL WAVE IS FORECAST TO MOVE ACROSS THE REGION ON WEDNESDAY
AND THURSDAY. WHILE THE WAVE WILL BRING AN INCREASE IN LOW-LEVEL
MOISTURE AND RESULT IN A HIGHER FREQUENCY OF PASSING SHOWERS, MODEL
GUIDANCE SUGGESTS PRECIPITABLE WATER VALUES WILL REMAIN NEAR
SEASONAL LEVELS. IN ADDITION, MID-LEVEL RELATIVE HUMIDITY IS
EXPECTED TO REMAIN RELATIVELY LOW, WHILE TEMPERATURES NEAR 500 MB
STAY CLOSE TO NORMAL, LIMITING THE POTENTIAL FOR WIDESPREAD DEEP
CONVECTION. AS A RESULT, PERIODS OF PASSING SHOWERS ARE EXPECTED,
PARTICULARLY ACROSS WINDWARD AND EASTERN SECTIONS DURING THE MORNING
HOURS AND ACROSS WESTERN PUERTO RICO DURING THE AFTERNOON DUE TO
LOCAL EFFECTS. HOWEVER, SIGNIFICANT RAINFALL ACCUMULATIONS ARE NOT
ANTICIPATED AT THIS TIME.
DUST AEROSOL MODEL GUIDANCE SUGGESTS THAT LOW TO MODERATE
CONCENTRATIONS OF SAHARAN DUST MAY REACH THE LOCAL ISLANDS BY
THURSDAY. THE ARRIVAL OF THIS DUST COULD PROMOTE HAZY SKIES AND
OCCASIONALLY REDUCED VISIBILITY WHILE ALSO CONTRIBUTING TO A MORE
STABLE ATMOSPHERE. ALTHOUGH THE TROPICAL WAVE IS EXPECTED TO ENHANCE
SHOWER ACTIVITY, THE EXTENT TO WHICH RAINFALL ASSOCIATED WITH THE
WAVE OFFSETS THE EFFECTS OF THE DUST REMAINS SOMEWHAT UNCERTAIN.
THEREFORE, RESIDENTS AND VISITORS ARE ENCOURAGED TO CONTINUE
MONITORING THE LATEST FORECASTS FOR UPDATES REGARDING BOTH RAINFALL
POTENTIAL AND AIR QUALITY CONDITIONS. AT THIS TIME, THE HIGHEST
CONCENTRATIONS OF SAHARAN DUST WILL FRIDAY. THERFORE, THOSE WITH
RESPIRATORY CONDITIONS ARE URGED TO FOLLOW THE HEALTH EXPERTS
RECOMMENDATIONS AND AVOID OUTDOOR ACTIVITIES.
BY FRIDAY AND CONTINUING THROUGH SATURDAY, MOISTURE LEVELS ARE
EXPECTED TO REMAIN NEAR TO SLIGHTLY BELOW SEASONAL NORMALS WHILE
RELATIVELY DRY MID-LEVEL AIR PERSISTS ACROSS THE REGION. THIS SHOULD
SUPPORT A DECREASE IN SHOWER COVERAGE AND A RETURN TO A MORE TYPICAL
TRADE-WIND WEATHER PATTERN. NEVERTHELESS, PATCHES OF SHALLOW
MOISTURE EMBEDDED WITHIN THE TRADES MAY STILL RESULT IN BRIEF
PASSING SHOWERS ACROSS WINDWARD AREAS FROM TIME TO TIME.
TEMPERATURES WILL CONTINUE NEAR SEASONAL NORMALS. WHILE NO
SIGNIFICANT WEATHER IMPACTS ARE ANTICIPATED THROUGH THE END OF THE
FORECAST PERIOD, THOSE PLANNING OUTDOOR ACTIVITIES SHOULD REMAIN
AWARE OF PASSING SHOWERS AND ANY LINGERING HAZY CONDITIONS THAT
COULD PRODUCE LOCALIZED VISIBILITY REDUCTIONS.
AVIATION
(06Z TAFS)
ISSUED AT 250 AM AST SUN JUN 21 2026
A TROPICAL WAVE WILL BRING SHRA/-SHRA, FIRST ACROSS ISX, AND LATER
THIS MORNING NEAR IST, SPREADING INTO EASTERN PR< WHERE JSJ WILL
POSSIBLY BE AFFECTED BY THIS ACTIVITY. THERE IS A GOOD CHANCE OF
OBSERVING TSRA/+TSRA FROM MID-MORNING INTO THE AFTERNOON ACROSS
THE INTERIOR SECTIONS OF PR, BUT THE USVI COULD SEE IT, MAINLY
ACROSS THE SURROUNDING WATERS. WINDS WILL BE FROM THE E-ESE AT 5
TO 15 KT THROUGH 21/13Z, THEN AT 10-20KT WITH GUSTS UP TO 30 KT,
ESPECIALLY AROUND SHRA/TSRA AND DUE TO SEA BREEZE.
MARINE
ISSUED AT 250 AM AST SUN JUN 21 2026
A BROAD SURFACE HIGH PRESSURE SYSTEM BUILDING ACROSS THE CENTRAL
ATLANTIC WILL CONTINUE TO PROMOTE MODERATE TO LOCALLY FRESH EASTERLY
TO EAST-SOUTHEASTERLY WINDS OVER THE NEXT SEVERAL DAYS. THESE
CONDITIONS WILL MAINTAIN CHOPPY SEAS ACROSS THE LOCAL WATERS AND
CARIBBEAN PASSAGES, AND SMALL CRAFT SHOULD EXERCISE CAUTION.
MEANWHILE, MODERATE TO OCCASIONALLY HIGH CONCENTRATIONS OF SAHARAN
DUST WILL PERSIST THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK,
RESULTING IN HAZY SKIES, REDUCED VISIBILITIES, AND DEGRADED AIR
QUALITY. A TROPICAL WAVE MOVING ACROSS THE CARIBBEAN SEA TODAY INTO
MONDAY WILL INCREASE MOISTURE ACROSS THE REGION, LEADING TO A HIGHER
LIKELIHOOD OF SHOWERS AND ISOLATED THUNDERSTORMS OVER THE REGIONAL
WATERS.
BEACH FORECAST
ISSUED AT 250 AM AST SUN JUN 21 2026
A MODERATE RISK OF RIP CURRENTS CONTINUES FOR THE NORTH AND EAST-
FACING BEACHES OF PUERTO RICO, INCLUDING VIEQUES AND CULEBRA, AND
ACROSS THE U.S. VIRGIN ISLANDS, WHILE A LOW RISK REMAINS ALONG THE
SOUTH AND WEST COASTS OF PUERTO RICO. LIFE-THREATENING RIP CURRENTS
REMAIN POSSIBLE ALONG BEACHES WITH A MODERATE RISK. ON SUNDAY,
INCREASING SHOWERS ARE EXPECTED ACROSS EASTERN PUERTO RICO, WHILE
ISOLATED THUNDERSTORMS MAY DEVELOP OVER NORTHWESTERN PUERTO RICO
DURING THE AFTERNOON HOURS. IN ADDITION, MODERATE TO HIGH
CONCENTRATIONS OF SAHARAN DUST WILL CONTINUE TO MOVE ACROSS THE
REGION, RESULTING IN HAZY SKIES, REDUCED VISIBILITY, AND POOR AIR
QUALITY.
FIRE WEATHER
ISSUED AT 250 AM AST SUN JUN 21 2026
A TROPICAL WAVE WILL BRING BENEFICIAL RAINS ACROSS PORTIONS OF THE
ISLANDS TODAY. WINDS WILL PREVAIL MAINLY FROM THE EAST TO EAST-
SOUTHEAST AT 10 TO 20 MPH, WITH GUSTS UP TO 33 MPH, ESPECIALLY
FROM MID MORNING INTO THE AFTERNOON. THE TROPICAL WAVE WILL
MAINTAIN RH VALUES ABOVE CRITICAL LEVELS.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
KEY MESSAGES/SHORT TERM/AVIATION/FIRE WEATHER...CAM
LONG TERM....MMC
MARINE/BEACH FORECAST...ICP
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