862
FXCA62 TJSJ 251616
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1216 PM AST SAT JUL 25 2026
..UPDATE
A HEAT ADVISORY WAS ISSUED DUE TO AN INCREASE IN THE HEAT INDICES
ALONG MOST OF THE COASTAL AND URBAN AREAS. THE ADVISORY WILL BE
IN EFFECT FROM NOW ALL THE WAY TROUGH 4 PM. ALTHOUGH SHOWERS HAD
DEVELOP ACROSS THE INTERIOR SECTIONS, THE AVAILABLE MOISTURE WITH
THE ACTUAL WARM TEMPERATURES WILL HOLD HEAT STRESS CONDITIONS FOR
THE REST OF THE AFTERNOON.
SHORT TERM(TODAY THROUGH MONDAY)
ISSUED AT 232 AM AST SAT JUL 25 2026
A WIND SURGE AHEAD OF A TROPICAL WAVE WILL CONTINUE TO BRING
PATCHES OF LOW-LEVEL MOISTURE ACROSS THE REGION TODAY. BREEZY
EASTERLY TRADE WINDS AND PASSING SHOWERS CAN BE EXPECTED
THROUGHOUT THE DAY, WHILE WEAKENING OF THE SAHARAN AIR LAYER WILL
REDUCE DUST CONCENTRATIONS. HOWEVER, THE AVAILABLE LOW-LEVEL
MOISTURE WILL COMBINE WITH DIURNAL HEATING AND LOCAL OROGRAPHIC
EFFECTS TO PRODUCE LOCALIZED AFTERNOON SHOWERS AND ISOLATED
THUNDERSTORMS ONCE AGAIN ACROSS THE INTERIOR AND WESTERN PR. MAX
TEMPS ARE EXPECTED TO RANGE FROM THE UPPER 80S TO LOW 90S ACROSS
THE LOWER ELEVATIONS, AND FROM THE UPPER 70S TO MID 80S ACROSS THE
HIGHER ELEVATIONS OF THE ISLANDS. HEAT INDICES ARE EXPECTED TO
REMAIN BELOW HEAT ADVISORY CRITERIA DUE TO THE EXPECTED CLOUD
COVERAGE.
THE WEATHER PATTERN WILL EVOLVE FROM LATE SUNDAY INTO MONDAY AS
THE TROPICAL WAVE APPROACHES THE ISLANDS. SIMULTANEOUSLY, AN
UPPER-LEVEL LOW IS EXPECTED TO MOVE OVER THE REGION, LOWERING
250MB HEIGHTS AND DROPPING MID-LEVEL (500MB) TEMPERATURES DOWN TO
AROUND -9C, ERODING THE LOW-LEVEL TRADE WIND CAP AND DESTABILIZING
THE ATMOSPHERIC COLUMN. MOISTURE CONTENT WILL GRADUALLY INCREASE,
WITH GUIDANCE SHOWING PRECIPITABLE WATER (PWAT) VALUES SURGING
ABOVE SEASONAL LEVELS, EXCEEDING 2.00 INCHES THROUGH THIS PERIOD.
WITH LIGHTER STEERING WINDS AND HIGHER MOISTURE CONTENT ON MONDAY,
SLOW-MOVING SHOWERS AND THUNDERSTORM CLUSTERS ARE ANTICIPATED TO
DEVELOP OVER PORTIONS OF THE ISLANDS AND REGIONAL WATERS. THE
STRONGEST CONVECTIVE DEVELOPMENT WILL FOCUS OVER THE INTERIOR,
NORTHERN, AND WESTERN PORTIONS OF PUERTO RICO DURING THE
AFTERNOON. PROLONGED HEAVY RAINFALL FROM THESE SLOW-MOVING CELLS
WILL ELEVATE THE POTENTIAL FOR URBAN AND SMALL STREAM FLOODING,
LOCALIZED RIVER RISES, AND PONDING OF WATER ON ROADWAYS AND POORLY
DRAINED AREAS. ADDITIONALLY, DUE TO THE EXPECTED FAVORABLE
POSITION OF THE UPPER-LEVEL LOW, THESE THUNDERSTORMS CAN PRODUCE
FREQUENT LIGHTNING AND STRONG GUSTY WINDS.
LONG TERM(TUESDAY THROUGH FRIDAY)
ISSUED AT 232 AM AST SAT JUL 25 2026
THE LATEST MODEL GUIDANCE CONTINUES TO SUGGEST ABOVE-NORMAL
PRECIPITABLE WATER (PWAT) VALUES EXCEEDING 2.00 INCHES BY THE
BEGINNING OF THE LONG-TERM PERIOD, AS MOISTURE ASSOCIATED WITH A
PASSING TROPICAL WAVE CONTINUES TO LINGER ACROSS THE AREA. AT THE
UPPER LEVELS, AN UPPER-LEVEL LOW WILL BEGIN TO MIGRATE NORTHWESTWARD
AWAY FROM THE REGION, PROVIDING SOME STABILITY ALOFT THAT WILL BE
REFLECTED IN RISING HEIGHTS AND WARMER MID-LEVEL TEMPERATURES (AT
500 MB). AT THE SURFACE, A HIGH-PRESSURE SYSTEM WILL CONTINUE TO
STRENGTHEN, RESULTING IN BREEZY TO LOCALLY WINDY EAST-SOUTHEASTERLY
WINDS ACROSS THE AREA.
UNDER THIS SCENARIO, MOISTURE CONTENT WILL REMAIN ABOVE AVERAGE AND
WHEN COMBINED WITH LOCAL EFFECTS AND DIURNAL HEATING, WILL LIKELY
SUPPORT FAST MOVING SHOWERS DURING THE MORNING HOUR ACROSS THE
WINDWARD AREAS OF THE ISLANDS, FOLLOWED BY AFTERNOON CONVECTION
ACROSS THE INTERIOR AND WESTERN PORTIONS OF PUERTO RICO. DURING THIS
PERIOD, PONDING OF WATER ON ROADS AND IN POORLY DRAINED AREAS IS
POSSIBLE.
FROM WEDNESDAY ONWARDS, A DRIER AIRMASS WILL FILTER INTO THE REGION,
DROPPING PWAT VALUES BELOW NORMAL TO AROUND 1.30 INCHES. THIS DRIER
AIRMASS WILL BE ACCOMPANIED BY LOW CONCENTRATIONS OF SAHARAN DUST
THROUGH AT LEAST SATURDAY. DESPITE THE EXPECTED DRIER PATTERN,
PATCHES OF MOISTURE EMBEDDED IN THE TRADE WINDS WILL CONTINUE TO
REACH THE REGION, BRINGING FAST-MOVING, PASSING SHOWERS ACROSS
PORTIONS OF PUERTO RICO AND THE U.S. VIRGIN ISLANDS WITH MINIMAL TO
NO IMPACTS. NORMAL TO ABOVE-NORMAL TEMPERATURES WILL PERSIST ACROSS
THE AREA, WITH DAYTIME HIGHS REMAINING BETWEEN THE UPPER 80S AND LOW
90S IN COASTAL AND URBAN LOCATIONS. RESIDENTS AND VISITORS ARE
ENCOURAGED TO STAY HYDRATED AND MONITOR LOCAL WEATHER UPDATES.
AVIATION
(06Z TAFS)
ISSUED AT 232 AM AST SAT JUL 25 2026
A WIND SURGE AND THE PROXIMITY OF AN UPPER-LEVEL LOW WILL BRING
QUICK PASSING SHRA AND BRIEF GUSTY WINDS ACROSS THE USVI/EASTERN
PR TERMINALS THROUGH THE EARLY MORNING HOURS. THIS MAY LEAD TO
BRIEF MVFR CIGS. ISO TSTMS WITH MAX TOPS TO 380 WERE OBSERVED
S-SW OF ST. CROIX, AND MAY CAUSE VCTS TILL SUNRISE. AFTERNOON
SHRA/TSRA EXPECTED TO DEVELOP IN AND AROUND THE PR TERMINALS THRU
SUNSET. HOWEVER, MOSTLY VCSH/VCTS EXPECTED. HZ DUE TO SAHARAN
DUST WILL CONTINUE BUT VSBY SHOULD REMAIN P6SM. EAST WINDS AT
15-25 KT BLO FL080.
MARINE
ISSUED AT 232 AM AST SAT JUL 25 2026
MODERATE TO LOCALLY FRESH EASTERLY WINDS WILL CONTINUE THROUGH THE
WEEKEND, PRODUCING CHOPPY SEAS AND HAZARDOUS CONDITIONS FOR SMALL
CRAFT ACROSS PORTIONS OF THE LOCAL WATERS. WINDS ARE EXPECTED TO
DECREASE EARLY NEXT WEEK, LEADING TO IMPROVING MARINE CONDITIONS.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL INCREASE LATE
SUNDAY INTO MONDAY AS A TROPICAL WAVE APPROACHES. SAHARAN DUST WILL
GRADUALLY DIMINISH, ALTHOUGH LOW CONCENTRATIONS WILL LINGER INTO
EARLY NEXT WEEK.
BEACH FORECAST
ISSUED AT 232 AM AST SAT JUL 25 2026
A MODERATE RISK OF RIP CURRENTS WILL CONTINUE THROUGH THE REST OF
THE WEEKEND ACROSS BEACHES OF NORTHERN AND EASTERN PUERTO RICO,
VIEQUES, CULEBRA, AND ST. CROIX. AS WINDS DECREASE EARLY NEXT
WEEK, THE RIP CURRENT RISK SHOULD GRADUALLY LESSEN, RESULTING IN
IMPROVING BEACH CONDITIONS THROUGH MIDWEEK. HOWEVER, LIFE-
THREATENING RIP CURRENTS WILL REMAIN POSSIBLE NEAR REEFS, JETTIES,
GROINS, AND PIERS. THE RIP CURRENT RISK IS EXPECTED TO INCREASE
AGAIN LATER IN THE WORKWEEK AS EASTERLY WINDS STRENGTHEN.
BEACHGOERS SHOULD ALSO REMAIN ALERT FOR THUNDERSTORMS AND HEAT.
SJU WATCHES/WARNINGS/ADVISORIES
PR...HEAT ADVISORY UNTIL 4 PM AST THIS AFTERNOON FOR PRZ001>005-007-
008-010-011.
VI...NONE.
AM...NONE.
SHORT TERM...DS
LONG TERM....GRS
AVIATION...DSR
UPDATE...LIS
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