309
FXCA62 TJSJ 060859
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
459 AM AST TUE MAY 6 2025
KEY MESSAGES
* AFTERNOON SHOWERS AND THUNDERSTORMS WILL CONTINUE TO POSE AN
ELEVATED THREAT OF FLOODING, ESPECIALLY TODAY AND WEDNESDAY.
* DUE TO ONGOING SOIL SATURATION, THE RISK OF MUDSLIDES/LANDSLIDES
PERSISTS ALONG THE STEEP TERRAINS.
* CONDITIONS WILL GRADUALLY IMPROVE AFTER MIDWEEK AS A SOMEWHAT
DRIER AIR MASS AND MORE STABLE CONDITIONS BUILD OVER THE
ISLANDS.
* THE RISK OF RIP CURRENTS WILL BECOME MODERATE BY SUNDAY AND
MONDAY AS THE EASTERLY WINDS INCREASE ACROSS THE ISLANDS.
SHORT TERM...TODAY THROUGH THURSDAY
MOSTLY CALM WEATHER CONDITIONS PREVAILED OVERNIGHT ACROSS PUERTO
RICO AND THE U.S. VIRGIN ISLANDS. DOPPLER RADAR AND SATELLITE
OBSERVATIONS SHOWED THE DEVELOPMENT OF PASSING SHOWERS, MAINLY OVER
THE LOCAL CARIBBEAN WATERS. WINDS WERE LIGHT AND VARIABLE THROUGHOUT
MUCH OF THE NIGHT. MINIMUM TEMPERATURES WERE SEEN IN THE MID TO
UPPER 60S IN THE MOUNTAINS, AND FROM THE LOW TO MID 70S ALONG THE
COASTAL AND URBAN AREAS.
TODAY, FAIR WEATHER CONDITIONS ARE EXPECTED TO PREVAIL DURING THE
MORNING HOURS WITH FEW PASSING SHOWERS REACHING THE WINDWARD
PORTIONS OF THE ISLANDS. HOWEVER, THE PROXIMITY OF A SHORT WAVE
TROUGH ALOFT AND ABUNDANT MOISTURE OVER THE REGION WILL HELP TO
ENHANCE AFTERNOON CONVECTIVE ACTIVITY OVER PUERTO RICO TODAY THROUGH
WEDNESDAY. THE LATEST PRECIPITABLE WATER CONTENT GUIDANCE (PWAT) HAS
VALUES OF 1.8 TO 2.0 INCHES. IN ADDITION, AT THE 500 MB LEVEL THE
TEMPERATURES WILL DROP INTO -8 TO -9 DEGREES CELSIUS, INCREASING THE
POTENTIAL TO SUPPORT DEEP CONVECTION. UNDER THIS MOIST ENVIRONMENT
IN COMBINATION WITH DAYTIME HEATING AND LOCAL EFFECTS, HEAVY SHOWERS
WITH THUNDERSTORMS ARE LIKELY OVER THE INTERIOR AND WESTERN PUERTO
RICO. THEREFORE, THERE IS A LIMITED TO ELEVATED RISK OF FLOODING
RAINS, ONCE AGAIN, OVER THE ISLANDS. WEATHER CONDITIONS WILL LIKELY
IMPROVE FROM THURSDAY ONWARD WITH THE ENTRANCE OF A DRIER AIRMASS
INTO THE REGION WITH PWAT VALUES AT NORMAL-TO-BELOW NORMAL
CLIMATOLOGICAL VALUES (1.4 TO 1.6 INCHES).
SEASONAL TEMPERATURES WILL CONTINUE OVER THE NEXT SEVERAL DAYS.
MAXIMUM TEMPERATURES ARE EXPECTED TO REMAIN IN THE MID 80S ALONG THE
COASTAL AND URBAN AREAS, AND FROM THE UPPER 70S TO LOW 80S ACROSS
THE CENTRAL MOUNTAIN RANGE.
DUE TO THE RECENT RAIN EVENTS OVER PUERTO RICO, SOILS ARE VERY
SATURATED AND ANY ADDITIONAL RAINFALL ACTIVITY COULD LEAD TO FLASH
FLOODING, MUDSLIDES AND LANDSLIDES, QUICK RIVER RISES, AND WATER
SURGES ALONG ALREADY IMPACTED AREAS. RESIDENTS AND VISITORS SHOULD
CONTINUE TO MONITOR THE WEATHER CONDITIONS IN YOUR LOCATION AS THE
DAY PROGRESSES FOR SAFETY CONCERNS.
LONG TERM...FRIDAY THROUGH TUESDAY
WHEN THE UPPER-LEVEL TROUGH EXITS THE REGION BY FRIDAY, MOVING
EASTWARD INTO THE ATLANTIC OCEAN, MODEL GUIDANCE INDICATES DRY AIR
INTRUSION ABOVE 700 MB OVER THE NORTHEAST CARIBBEAN. THIS AIR
MASS ALOFT WILL INDUCE SUBSIDENCE, LIMITING THE POTENTIAL FOR
WIDESPREAD RAIN ACTIVITY EACH DAY. HOWEVER, AT LOW LEVELS,
SUFFICIENT TROPICAL MOISTURE INTERACTING WITH THE EASTERLY WINDS
WILL CONTINUE TO PROMOTE PERIODS OF SHOWERS ACROSS THE WINDWARD
LOCATIONS IN THE US VIRGIN ISLANDS AND PUERTO RICO, MAINLY DUE TO
LOW-LEVEL CONVERGENCE, FOLLOWED BY AFTERNOON CONVECTION OVER THE
INTERIOR AND WESTERN PUERTO RICO DUE TO SEA BREEZE, LOCAL EFFECTS,
AND DIURNAL HEATING EACH DAY.
WINDS WILL INCREASE BY THE END OF THE WEEK AS A SURFACE HIGH-
PRESSURE BUILDING ACROSS THE CENTRAL ATLANTIC TIGHTENS THE LOCAL
PRESSURE GRADIENT. AN ADVECTIVE PATTERN MAY INCREASE THE FREQUENCY
OF THE TYPICAL PASSING SHOWERS ACROSS THE WINDWARD LOCATIONS,
MOVING FURTHER INLAND ACROSS PR DUE TO THESE RISING WINDS.
MODEL GUIDANCE SHOWS ANOTHER DEEP TROUGH APPROACHING THE
NORTHEAST CARIBBEAN BY NEXT TUESDAY, POTENTIALLY INCREASING THE
INSTABILITY OVER THE REGION AND THE LIKELIHOOD FOR THUNDERSTORM
DEVELOPMENT WITH FLOODING RAIN.
AVIATION
(06Z TAFS)
MAINLY VFR CONDS WILL PREVAIL ACROSS ALL TAF SITES DURING THE
FORECAST PERIOD. HOWEVER, SHRA/TSRA DEVELOPMENT IS LIKELY OVER THE
VICINITY OF TJPS, RESULTING IN PERIODS OF BRIEF MVFR CONDS AFT 6/17-
22Z. CALM TO LIGHT VRB WINDS WILL PREVAIL THRU 5/13Z, THEN
INCREASING AT 10-13 KT FROM THE ENE WITH HIGHER GUSTS AND SEA
BREEZE VARIATIONS.
MARINE
A BROAD SURFACE HIGH PRESSURE EXTENDING INTO THE CENTRAL ATLANTIC,
IN COMBINATION WITH AN INDUCED SURFACE TROUGH NORTHEAST OF THE
REGION, WILL RESULT IN LIGHT TO MODERATE EASTERLY WINDS ACROSS THE
LOCAL WATERS TODAY, THEN BECOMING LIGHT TO GENTLE THROUGH THE END OF
THE WORKWEEK. MARINERS CAN EXPECT SEAS BETWEEN 2 TO 4 FEET,
OCCASIONALLY 5 FEET, FOR THE NEXT SEVERAL DAYS. OCCASIONAL
THUNDERSTORMS ARE LIKELY ACROSS THE REGIONAL WATERS, ESPECIALLY IN
THE AFTERNOON, RESULTING IN DANGEROUS CONDITIONS FOR MARINERS.
CHOPPY SEAS MAY RETURN BY THE END OF THE WEEK AND EARLY NEXT WEEK.
BEACH FORECAST
BEACHGOERS CAN EXPECT A LOW RISK OF RIP CURRENTS ACROSS THE LOCAL
BEACHES. HOWEVER, REMEMBER THAT RIP CURRENTS OFTEN OCCUR NEAR
GROINS, JETTIES, REEFS, AND PIERS. THE RISK OF RIP CURRENTS WILL
BECOME MODERATE ON SUNDAY AND MONDAY NEXT WEEK.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
MIDNIGHT CREW...GRS/CAM
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