698
FXCA62 TJSJ 132012
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
412 PM AST SUN APR 13 2025
SYNOPSIS
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP EACH AFTERNOON
ACROSS THE ISLANDS, ENHANCING THE RISK FOR URBAN AND SMALL STREAM
FLOODING, AS WELL AS MUDSLIDES AND RAPID RIVER RISES. ALTHOUGH THE
HEAVIEST ACTIVITY IS EXPECTED TO FOCUS ACROSS THE INTERIOR INTO
WEST-NORTHWESTERN SECTIONS THROUGH MOST OF THE PERIOD, MONDAY'S
AFTERNOON HEAVY RAINS WILL FOCUS OVER THE SOUTHWESTERN QUADRANT.
OTHER HAZARD RISKS INCLUDE LIGHTNING AND EXCESSIVE HEAT OVER THE
NEXT FEW DAYS, WITH NON-THUNDERSTORM WIND RISKS ANTICIPATED ON
TUESDAY. THE RISK OF LIFE-THREATENING RIP CURRENTS WILL RISE TO
MODERATE BY TUESDAY NIGHT INTO WEDNESDAY FOR MOST NORTH- AND EAST-
FACING BEACHES.
SHORT TERM...NIGHT THROUGH TUESDAY
VARIABLY CLOUDY SKIES PREVAILED ACROSS PUERTO RICO AND THE US.
VIRGIN ISLANDS DURING THE MORNING WITH BRIEF PASSING SHOWERS
OBSERVED ACROSS THE EAST AND SOUTHEAST COASTAL AREAS OF PUERTO RICO.
NEVERTHELESS, RAINFALL ACCUMULATIONS ASSOCIATED WITH THESE SHOWERS
WERE MINIMAL. ALTHOUGH A DELAY IN THE ONSET OF AFTERNOON CONVECTION
WAS OBSERVED, SHOWERS WITH THUNDERSTORMS DEVELOPED - AS EXPECTED -
ACROSS NORTH-CENTRAL AND NORTHWEST PUERTO RICO IN THE AFTERNOON.
MAXIMUM RAINFALL ACCUMULATIONS WERE BETWEEN XX AND XX INCHES IN XX.
AS A SURFACE HIGH BUILDS ACROSS THE SOUTHWEST ATLANTIC AND NORTH OF
THE AREA TONIGHT INTO MONDAY, THE FRONTAL BOUNDARY OVER THE
HISPANIOLA WILL CONTINUE TO MOVE EAST WHILE DISSIPATING. AT UPPER
LEVELS, A BROAD MID- TO UPPER-LEVEL TROUGH WILL CONTINUE TO MOVE
ACROSS THE WESTERN ATLANTIC INTO THE CENTRAL ATLANTIC EARLY IN THE
CYCLE. ON TUESDAY, A MID-LEVEL RIDGE PATTERN WILL PREVAIL
MOMENTARILY ONCE THE AFOREMENTIONED UPPER-LEVEL TROUGH MOVES AWAY.
OVERALL, THE SHORT-TERM FORECAST IS STILL ON TRACK, WITH PASSING
SHOWERS EXPECTED ACROSS WINDWARD AREAS AND OUTLYING ISLANDS,
PARTICULARLY IN THE MORNING HOURS, AND AFTERNOON CONVECTION ACROSS
WESTERN REGIONS OF PUERTO RICO EACH DAY. DETERMINISTIC AND ENSEMBLE
GUIDANCE CONTINUES TO INDICATE PLENTY OF MOISTURE ACROSS THE
NORTHEAST CARIBBEAN DURING THE NEXT SEVERAL DAYS, WITH PRECIPITABLE
WATER (PW) VALUES NEAR OR EXCEEDING THE THRESHOLD VALUE OF 2 INCHES.
HAVING SAID THAT, THERE IS A HIGH CHANCE (>60%) OF RAINFALL TOTAL
ACCUMULATIONS EXCEEDING 1 INCH ACROSS THE WESTERN INTERIOR AND
CENTRAL PUERTO RICO MONDAY AFTERNOON. ON TUESDAY AFTERNOON, THIS
CHANCE IS MODERATE UNDER THE MID-LEVEL RIDGE PATTERN.
THIS WET PATTERN MARKS THE ONSET OF THE WET SEASON ACROSS THE LOCAL
ISLANDS WITH A RISK OF URBAN AND SMALL STREAM FLOODING EACH
AFTERNOON. PLEASE REFER TO ESFSJU FOR DETAIL.
LONG TERM...WEDNESDAY THROUGH SUNDAY
FROM PREVIOS DISCUSSION ISSUED AT 346 AM AST SUN APR 13 2025
UNSETTLED WEATHER CONDITIONS ARE EXPECTED TO CONTINUE ACROSS THE
ISLANDS THROUGH AT LEAST EARLY IN THE WEEKEND. ON WEDNESDAY, A
SURFACE LOW PRESSURE WILL DEVELOP NORTH OF THE ISLANDS WHILE
MOVING TOWARD THE NORTHEAST. THIS WILL MAINTAIN A STEADY
SOUTHERLY WIND FLOW FROM THE SURFACE ALL THE WAY UP INTO 700 MB.
THEN, LATE ON WEDNESDAY AND INTO THE END OF THE WEEK, A POLAR
TROUGH WILL MOVE INTO THE WESTERN ATLANTIC. THIS WILL WEAKEN THE
PRESSURE GRADIENT CONSIDERABLY, WITH WIND SPEEDS FALLING FROM
NEARLY 13 KTS ON WEDNESDAY, 7 KTS ON THURSDAY, AND 2-3 KTS ON
FRIDAY. THE WINDS WILL GRADUALLY SHIFT FROM THE SOUTH TOO, PULLING
MOISTURE FROM THE CARIBBEAN INTO THE ISLANDS. AS A RESULT,
SHOWERS WILL CONTINUE TO STREAM AT TIMES OVER EASTERN AND SOUTHERN
PUERTO RICO AND THE VIRGIN ISLANDS AT TIMES. HOWEVER, THE
STRONGEST ACTIVITY IS ANTICIPATED FOR THE INTERIOR, WESTERN AND
NORTHERN PUERTO RICO IN THE AFTERNOON AND EARLY EVENING HOURS. THE
MAIN THREAT WILL BE URBAN AND SMALL STREAM FLOODING, RAPID RIVER
RISES, MUDSLIDES AND LIGHTNING STRIKES FROM THE THUNDERSTORMS.
THIS TROUGH WILL ALSO ESCORT A COLD FRONT INTO THE REGION, AND IT
COULD CROSS THE ISLAND SON SATURDAY, AND WINDS WILL BEGIN TO SHIFT
FROM THE NORTH BY THEN. PLENTY OF MOISTURE SHOULD CONTINUE TO FIRE
UP CONVECTION ACROSS THE CORDILLERA CENTRAL IN THE AFTERNOON
HOURS. AFTER THE FRONT CROSSES THE ISLANDS, DRIER AIR WILL MOVE
IN, WITH COOLER TEMPERATURES, BREEZY CONDITIONS AND LESS RAIN IN
FORECAST.
BEFORE THE FRONT MOVES, FROM WEDNESDAY THROUGH FRIDAY, THE
SOUTHERLY WIND FLOW WILL CAUSE TEMPERATURES TO INCREASE, WITH HEAT
INDICES JUST ABOVE 102 DEGREES FOR URBAN AND COASTAL AREAS. AREAS
WITH A THICK CLOUD LAYER AND FREQUENT SHOWERS WILL SEE A RELIEF
FROM THESE HIGH TEMPERATURES.
AVIATION
(18Z TAFS)
BRIEF PERIODS OF MVFR CONDITIONS WILL REMAIN POSSIBLE AT JSJ AND JBQ
THROUGH ABOUT 13/22Z IN SHRA/TSRA. WINDS WILL PREVAIL FROM THE SE AT
10-15 KTS WITH STRONGER GUSTS, BECOMING LIGHT AND VARIABLE
OVERNIGHT. MNTN OBSC IS EXPECTED ALONG THE CORDILLERA CENTRAL
THROUGH AT LEAST 13/22Z.
MARINE
A BROAD SURFACE HIGH PRESSURE WILL REMAIN ANCHORED OVER THE CENTRAL
ATLANTIC, PROMOTING LIGHT TO MODERATE EAST TO SOUTHEAST WINDS
THROUGH THE WEEKEND. HOWEVER, ANOTHER SURFACE HIGH PRESSURE WILL
BUILD OVER THE WESTERN ATLANTIC, PUSHING A FRONT OVER THE LOCAL AREA
EARLY IN THE WEEK, PROMOTING MODERATE TO FRESH NORTHEAST WINDS.
SHOWER AND THUNDERSTORM ACTIVITY WILL DEVELOP EACH DAY, MAINLY ACROSS
THE ATLANTIC WATERS AND THE MONA PASSAGE.
BEACH FORECAST
LIGHT WINDS WILL MAINTAIN THE RISK OF RIP CURRENTS LOW THROUGH
TUESDAY. HOWEVER, INCREASING WINDS ON TUESDAY WILL LEAD TO
MODERATE RISK FOR MOST NORTH- AND EAST-FACING BEACHES. BE AWARE
THAT AFTERNOON THUNDERSTORMS POSE A THREAT OF LIGHTNING, MOSTLY
FOR THE BEACHES IN THE WEST AND NORTH COAST OF PUERTO RICO.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
SHORT TERM/AVIATION...OMS/ICP
MARINE....ICP
PUBLIC/UA...MRR/MNG
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page