762
FXCA62 TJSJ 021845
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
245 PM AST FRI MAY 2 2025
SYNOPSIS
UNSETTLE AND WET WEATHER CONDITIONS WILL PERSIST ACROSS THE
ISLANDS DURING THE REST OF TODAY INTO THE WEEKEND. ADDITIONALLY
RAIN ACTIVITY AND SATURATED SOILS WILL KEEP A SIGNIFICANT FLOODING
THREAT ALONG THE CORDILLERA CENTRAL AND WESTERN INTERIOR.
RESIDENTS AND VISITORS ARE URGED TO STAY TUNE TO THE WEATHER
CONDITIONS.
SHORT TERM...TONIGHT THROUGH SUNDAY
IMPORTANT: A FLOOD WATCH REMAINS IN EFFECT FOR PUERTO RICO THROUGH
AT LEAST SATURDAY.
TODAY, BRIEF PERIODS OF SUNSHINE AND PARTLY CLOUDY SKIES DOMINATED
MUCH OF PUERTO RICO AND THE U.S. VIRGIN ISLANDS. THESE CONDITIONS
ALLOWED TEMPERATURES TO RISE INTO THE UPPER 80S TO LOW 90S DEGREES
FAHRENHEIT ALONG COASTAL AREAS, WHILE MOUNTAINOUS REGIONS
EXPERIENCED TEMPERATURES IN THE UPPER 70S AND LOW 80S. HOWEVER, BY
LATE MORNING, SHOWERS BEGAN DEVELOPING ACROSS EASTERN PUERTO RICO,
SAINT THOMAS, SAINT JOHN, AND SAINT CROIX. RAINFALL INTENSIFIED
RIGHT AFTER THAT, SPREADING OVER THE CORDILLERA CENTRAL, SOUTH
CENTRAL AND NORTH WESTERN PUERTO RICO. BY THE EARLY AFTERNOON HOURS,
THUNDERSTORMS PROCEEDED TO DEVELOP OVER THE SAME VULNERABLE AREAS.
IN RECENT DAYS, THIS ACTIVITY HAS PRODUCED PONDING OF WATER ON
ROADWAYS, FLOODING IN POORLY DRAINED AREAS, ADDITIONAL LANDSLIDES,
AND RAPID RISES IN RIVERS, AND TODAY IS NO EXCEPTION. THIS IS DUE TO
ALREADY SATURATED SOILS AND RIVER LEVELS RUNNING ABOVE TO MUCH ABOVE
NORMAL, ACCORDING TO THE UNITED STATES GEOLOGICAL SURVEY (USGS)
RIVER SENSORS. THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO THE
EVENING HOURS.
THE CURRENT WET PATTERN WILL PERSIST THROUGH AT LEAST SATURDAY.
PRECIPITABLE WATER VALUES ARE FORECAST TO PEAK BETWEEN 2.15 AND 2.20
INCHES THROUGH SATURDAY BEFORE GRADUALLY DECREASING TO AROUND 1.80
INCHES BY SUNDAY EVENING. THIS ABOVE-NORMAL MOISTURE, COMBINED WITH
FAVORABLE MID- TO UPPER-LEVEL ATMOSPHERIC SUPPORT FROM A DEVELOPING
TROUGH OR LOW TO OUR NORTHWEST, WILL CONTINUE TO PROMOTE ISOLATED TO
SCATTERED THUNDERSTORMS WITH PERIODS OF HEAVY RAINFALL OVER THE NEXT
24 TO 36 HOURS. ON SUNDAY, ALTHOUGH OVERALL MOISTURE LEVELS ARE
EXPECTED TO DECLINE, AFTERNOON THUNDERSTORMS TRIGGERED BY DAYTIME
HEATING WILL LIKELY DEVELOP AGAIN OVER PUERTO RICO'S MOUNTAINOUS
REGIONS. THESE STORMS MAY PRODUCE LOCALIZED HEAVY RAINFALL AND RENEW
FLOOD CONCERNS DUE TO PERSISTENTLY SATURATED SOILS. RESIDENTS AND
VISITORS ARE STRONGLY ENCOURAGED TO MONITOR WEATHER CONDITIONS AND
BE PREPARED TO TAKE PROTECTIVE ACTION AGAINST FLOODING IMPACTS
THROUGH THE WEEKEND.
FOR THE ADDITIONAL INFORMATION AND UPDATES, PLEASE REFER TO: FLOOD
WATCH (FFASJU), HAZARDOUS WEATHER OUTLOOK (HWOSJU), GRAPHICAL
HAZARDOUS WEATHER OUTLOOK (HTTPS://WWW.WEATHER.GOV/ERH/GHWO?WFO=SJU)
LONG TERM...MONDAY THROUGH FRIDAY...FROM PREVIOUS DISCUSSION
NO SIGNIFICANT CHANGES WERE MADE TO THE LONG-TERM FORECAST. THE
SYNOPTIC PATTERN CONTINUES AS EXPECTED, WITH A SURFACE HIGH PRESSURE
BUILDING IN THE WESTERN ATLANTIC THAT SHOULD MOVE EASTWARD AND AN
INDUCED LOW LINGERING OVER THE CENTRAL ATLANTIC. THE MID TO
UPPER- LEVEL TROUGH HIGHLIGHTED BY THE GLOBAL MODELS FOR THE PAST
FEW DAYS IS STILL EXPECTED TO APPROACH THE CWA BY WEDNESDAY,
INCREASING INSTABILITY ALOFT. THE WIND PATTERN WILL BE VARIABLE,
AS ENE WINDS WILL REDUCE BY TUESDAY AND REMAIN LIGHT FOR THE REST
OF THE FORECAST PERIOD. REGARDING THE SHOWER ACTIVITY, THE LATEST
GLOBAL MODEL ENSEMBLES SHOWED AN INCREASE IN UNCERTAINTY, WITH
SOME MEMBERS GOING FOR A LESS AGGRESSIVE SOLUTION COMPARED TO THE
PAST FEW DAYS. HOWEVER, THEY STILL EXPECT PWAT VALUES TO REMAIN
NEAR TO ABOVE CLIMATOLOGICAL NORMALS (1.7 - 1.9 INCHES) THROUGHOUT
THE ENTIRE PERIOD. THE TEMPERATURES IN THE 500 MB SHOULD INCREASE
TO SEASONAL VALUES (AROUND -7 CELSIUS) BY MONDAY AND TUESDAY, BUT
WILL GET COLDER BY MIDWEEK (AROUND -8 CELSIUS). ADDITIONALLY,
STRONGER UPPER LEVEL WINDS SHOULD BRING VENTILATION ALOFT,
INCREASING INSTABILITY. THEREFORE, THERE'S CONFIDENCE OF
DEVELOPMENT OF THUNDERSTORMS DURING THE AFTERNOONS EACH DAY.
WINDWARD SECTIONS CAN EXPECT LIGHT TO MODERATE SHOWERS
MOVING OCCASIONALLY DURING THE NIGHT AND THE MORNING HOURS, WHILE
THE DEEP AFTERNOON CONVECTION WILL CONCENTRATE ON THE INTERIOR
PORTIONS OF PUERTO RICO. WITH THE RECENT HEAVY RAINFALL, ABOVE-
NORMAL STREAMFLOWS, SATURATED SOILS, AND THE EXPECTED CONDITIONS,
THE FLOOD THREAT REMAINS ELEVATED MAINLY OVER THE AFOREMENTIONED
AREAS. THERE SHOULD BE AN IMPROVEMENT IN THE WEATHER CONDITIONS BY
FRIDAY, AS A DRIER AIR MASS FILTERS INTO THE REGION, PROMOTING
STABLE CONDITIONS ACROSS THE LOCAL ISLANDS.
SEASONAL TEMPERATURES SHOULD PREVAIL FOR THE REST OF THE FORECAST
PERIOD, WITH THE HEAT RISK REMAINING LOW ACROSS THE CWA.
AVIATION
(18Z TAFS)
PERIODS OF SHRA AND TSRA WILL RESULT IN MVFR AND BRIEFLY IFR
CONDITIONS ALONG TJBQ AND TJPS. FOR TJSJ SHRA WITH VCTS WILL RESULT
IN LOWER CEILINGS, MAINTAINING BKN/OCV LYRS BTW FL020-F040 EXPECTED
UNTIL 02/23Z. STEERING WINDS WILL HAVE A MORE EASTERLY COMPONENT
TODAY PREVAILING AT THE SFC AND INCREASING BTW 12-16 KT. STRONGER
SUSTAINED WINDS BTW 16-21 KT ARE EXPECTED TONIGHT FROM 03/01Z-
03/06Z ACROSS THE ATLANTIC AND EASTERN WATERS BTW PR AND THE
USVI.FOR TOMORROW VCSH ARE FORECASTED FOR TIST AND TISX FROM 03/10-
0315Z.
MARINE
A SURFACE HIGH PRESSURE BUILDING ACROSS THE WESTERN ATLANTIC AND A
DEEP LAYERED TROUGH NORTHEAST OF THE REGION WILL CONTINUE PROMOTING
LIGHT TO MODERATE EAST-NORTHEAST TO NORTHEAST WINDS FOR THE REST
OF TODAY. AN INCREASE IN WINDS IS FORECAST FOR TONIGHT, RESULTING
IN BRIEFLY WINDS UP TO 20 KNOTS. FOR TOMORROW, WINDS WILL PERSIST
FROM THE EAST UP TO 15 KNOTS. SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP ACROSS THE LOCAL WATERS, PRODUCING LOCALLY
HIGHER WINDS AND SEAS. SMALL CRAFT SHOULD EXERCISE CAUTION AND
STAY WEATHER ALERT.
BEACH FORECAST
THE MODERATE RISK OF RIP CURRENTS WILL CONTINUE FOR THE BEACHES IN
NORTHERN PUERTO RICO, CULEBRA, AND ST. THOMAS AND ST. JOHN IN THE
U.S. VIRGIN ISLANDS. BEACHGOERS MUST EXERCISE CAUTION DUE TO
POSSIBLE LIFE- THREATENING RIP CURRENTS ALONG THE SURF ZONE AND
STAY WEATHER ALERT. THE RIP CURRENT RISK IS STILL EXPECTED TO
GRADUALLY DECREASE THIS WEEKEND INTO EARLY NEXT WEEK.
SJU WATCHES/WARNINGS/ADVISORIES
PR...FLOOD WATCH THROUGH SATURDAY MORNING FOR PRZ001>013.
VI...NONE.
AM...NONE.
SHORT TERM...MMC
LONG TERM...AVIATION...LIS
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