404
FXCA62 TJSJ 051856
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
256 PM AST MON MAY 5 2025
SYNOPSIS
A VARIABLE WEATHER PATTERN WILL PREVAIL ACROSS THE LOCAL ISLANDS.
FROM TUESDAY ONWARDS A DECREASE IN THE MOISTURE ALONG THE LOW TO
MID LEVELS WILL INDUCE MOSTLY LOCALIZED SHOWERS ACROSS THE
INTERIOR AND WESTERN PR. FROM WEDNESDAY ONWARDS, A SURFACE
PERTURBATION WILL RESULT IN VARIABLES WINDS BECOMING MORE FROM
THE NORTH- NORTHWEST.
SHORT TERM...TONIGHT THROUGH WEDNESDAY
THIS MORNING, CONDITIONS REMAINED RELATIVELY CALM WITH MOSTLY CLEAR
SKIES. TEMPERATURES RANGED FROM THE MID-80S TO LOW 90S ACROSS URBAN
AREAS, AND FROM THE UPPER 70S TO LOW 80S IN THE MOUNTAINS. HOWEVER,
BY THE AFTERNOON, THE COMBINATION OF DIURNAL HEATING, LOCAL
TOPOGRAPHY, SEA BREEZES, AND AVAILABLE SURFACE MOISTURE LED TO THE
DEVELOPMENT OF MODERATE TO LOCALLY HEAVY SHOWERS AND THUNDERSTORMS
OVER WESTERN AND INTERIOR PUERTO RICO. THESE AREAS, ALREADY
VULNERABLE DUE TO 12 TO 20 INCHES OF RAINFALL OVER THE PAST THREE
WEEKS, EXPERIENCED ADDITIONAL FLOODING, LANDSLIDES, AND RAPID RIVER
RISES. SHOWER DEVELOPED ACROSS THE INTERIOR ALONG THE CORDILLERA
CENTRAL WITH THE PEAK OF THE SHOWERS OVER OROCOVIS, UTUADO, AND
CIALES, SEVERAL FLASH FLOOD WARNING WERE ISSUED.
MODEL GUIDANCE SUGGESTS THAT A SHORTWAVE TROUGH ALOFT WILL MOVE
ACROSS THE REGION TUESDAY INTO WEDNESDAY. THIS FEATURE, COUPLED WITH
DEEPER MOISTURE POOLING OVER THE ISLANDS DURING PEAK AFTERNOON
HEATING, IS EXPECTED TO SUPPORT THE DEVELOPMENT OF ADDITIONAL
SHOWERS AND THUNDERSTORMS. BY TUESDAY EVENING, SHIFTING WINDS FROM
THE NORTHEAST WILL ENHANCE INTERACTION WITH LAND BREEZES,
POTENTIALLY TRIGGERING ADDITIONAL ACTIVITY ALONG PUERTO RICO
ATLANTIC COAST. ON WEDNESDAY, THE AFTERNOON ACTIVITY IS FORECAST TO
DEVELOP OVER EASTERN PUERTO RICO AS WELL AS OVER THE SOUTHWESTERN
SECTIONS. AS THE MID-TO-UPPER-LEVEL TROUGH DEEPENS OVER THE
NORTHEASTERN CARIBBEAN, INSTABILITY WILL INCREASE, SUPPORTING DEEPER
CONVECTION. HOWEVER, MOST MODELS SUGGEST MOISTURE EROSION AND
PRECIPITABLE WATER VALUES RANGING NEAR NORMAL FOR THIS TIME OF THE
YEAR, MEANING THAT THERE IS POTENTIAL TO OBSERVE LIMITED RAINFALL
COVERAGE. WE WILL CONTINUE TO CLOSELY MONITOR EVOLVING CONDITIONS,
AS DAILY AFTERNOON CONVECTION IS EXPECTED THROUGH THE SHORT-TERM
PERIOD. THEREFORE, THE LIMITED TO ELEVATED RISK OF FLOODING ACROSS
THE ISLANDS REMAINS THROUGHOUT THE WORKWEEK.
LONG TERM...THURSDAY THROUGH MONDAY...FROM PREVIOUS DISCUSSION
A STRONG SURFACE HIGH PRESSURE LOCATED OVER THE CENTRAL TOWARD THE
NORTHEASTERN ATLANTIC WILL PROMOTE EAST TO SOUTHEASTERLY WINDS
THROUGHOUT THE FORECAST PERIOD. WINDS WILL BECOME FROM THE EAST ON
SUNDAY, AS ANOTHER SURFACE HIGH BUILDS OVER THE WESTERN ATLANTIC AND
MOVES TOWARD THE CENTRAL ATLANTIC. A MID-LEVEL RIDGE IS EXPECTED TO
BUILD OVER THE REGION, PROMOTING RELATIVELY DRIER CONDITIONS AND
STABILITY ALOFT. THE LATEST PRECIPITABLE WATER CONTENT HAS NEAR
NORMAL CLIMATOLOGICAL VALUES FROM 1.4 TO 1.6 INCHES. UNDER THIS
PATTERN, LIMITED RAINFALL ACTIVITY IS EXPECTED OVER THE AREA.
HOWEVER, AFTERNOON SHOWERS ARE POSSIBLE OVER PORTIONS OF THE
INTERIOR, WESTERN AND NORTHERN PUERTO RICO WITH ISOLATED
THUNDERSTORMS DUE TO THE COMBINATION OF DAYTIME HEATING AND
TOPOGRAPHIC EFFECT. BY THE END NEXT WEEKEND, A WIND SURGE COULD
POTENTIALLY REACHED THE AREA, INCREASING ONCE AGAIN THE LIKELIHOOD
TO OBSERVE SHOWERS SHOWERS AND ISOLATED THUNDERSTORMS OVER THE
ISLAND. THE 925 MB TEMPERATURES WILL REMAIN AT NORMAL
CLIMATOLOGICAL VALUES FOR THIS TIME OF THE YEAR, WITH TEMPERATURES
IN THE MID 80S ALONG THE COASTAL AND URBAN AREAS; AND FROM THE
MID TO UPPER 70S IN THE MOUNTAINS. ACROSS THE U.S. VIRGIN ISLANDS,
MAINLY FAIR WEATHER CONDITIONS WILL PREVAIL WITH LIMITED OR NONE
PRECIPITATION.
AVIATION
(18Z TAFS)
VFR CONDITIONS WILL PERSIST ACROSS MOST TAF SITES. HOWEVER,
SHRA/TSRA WILL IMPACTING THE VICINITY OF JPS/JBQ AFTER 05/18Z-22Z,
WITH MVFR CONDITIONS LIKELY, IF IT MOVES OVER THOSE TERMINALS.
THE WINDS WILL BE CALM TO LIGHT AND VRB AFTER 05/23Z.
MARINE
A BROAD SURFACE HIGH PRESSURE EXTENDING FROM THE WESTERN INTO THE
CENTRAL ATLANTIC, IN COMBINATION WITH AN INDUCED SURFACE TROUGH JUST
NORTHEAST OF THE REGION, WILL RESULT IN LIGHT TO MODERATE EASTERLY
WINDS ACROSS THE LOCAL WATERS. MARINERS CAN EXPECT SEAS BETWEEN 3 TO
5 FEET FOR THE NEXT SEVERAL DAYS. THUNDERSTORMS ARE LIKELY TODAY
ACROSS THE REGIONAL WATERS, RESULTING IN HIGHER SEAS WITH THE
STRONGEST ACTIVITY. VARIABLE WINDS FROM CALM TO LIGHT WILL BE
PRESENT FROM WEDNESDAY ONWARDS ALONG THE LOCAL WATERS.
BEACH FORECAST
THERE IS A MODERATE RISK OF RIP CURRENTS FOR THE BEACHES OF PUERTO
RICO FROM AGUADILLA TO FAJARDO. 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 BY TUESDAY THROUGH THE REST OF THE WEEK.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
SHORT TERM...MMC
LONG TERM....GRS
AVIATION...LIS
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