324
FXCA62 TJSJ 140847
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
447 AM AST MON APR 14 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. TODAYS
HEAVY RAINS WILL FOCUS OVER THE SOUTHWESTERN QUADRANT. OTHER
HAZARD RISKS INCLUDE LIGHTNING 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 FOR MOST
NORTH- AND EAST-FACING BEACHES.
SHORT TERM...TODAY THROUGH WEDNESDAY
A VARIABLE WEATHER PATTERN PREVAILED ACROSS PUERTO RICO AND THE U.S.
VIRGIN ISLANDS WITH CLOUDY SKIES AND SOME SHOWERS. AT AROUND 1 AM,
SHOWER ACTIVITY MOVED OVER THE NORTH-CENTRAL SECTIONS OF PUERTO
RICO. RAINFALL ACCUMULATIONS ASSOCIATED WITH THESE SHOWERS REMAINED
AT LESS THAN 1 INCH, WITH THE HIGHEST AMOUNTS OVER ARECIBO.
OVERNIGHT TEMPERATURES REMAINED IN THE UPPER 60S TO LOWER 70S ACROSS
THE MOUNTAINS AND IN THE UPPER 70S TO LOWER 80S ACROSS THE COASTAL
AREAS.
PUERTO RICO AND THE U.S. VIRGIN ISLANDS REMAIN UNDER A MOIST AND
SOMEWHAT UNSTABLE WEATHER PATTERN. AN APPROACHING FRONTAL BOUNDARY
CONTINUES TO ENHANCE MOISTURE CONTENT ACROSS THE REGION, WITH
PRECIPITABLE WATER VALUES NEAR OR ABOVE THE 75TH PERCENTILE, AROUND
1.75 INCHES. AT THE SURFACE, A BUILDING HIGH-PRESSURE SYSTEM OVER
THE WESTERN ATLANTIC IS PRODUCING A NORTHEASTERLY WIND FLOW,
STEERING MOISTURE TOWARD THE ISLANDS. AS A RESULT, SCATTERED SHOWERS
ARE EXPECTED ACROSS WINDWARD COASTAL AREAS DURING THE MORNING,
FOLLOWED BY AFTERNOON CONVECTION FOCUSED OVER THE SOUTHWESTERN
QUADRANT OF PUERTO RICO DUE TO LOCAL AND DIURNAL EFFECTS. CONDITIONS
ALOFT ARE MODESTLY UNSTABLE, WITH 500 MB TEMPERATURES NEAR -8°C
SUPPORTING THE POTENTIAL FOR ISOLATED THUNDERSTORMS. BY TUESDAY, THE
HIGH-PRESSURE SYSTEM WILL CONTINUE TO SHIFT EASTWARD ACROSS THE
ATLANTIC, ALLOWING SURFACE WINDS TO GRADUALLY VEER FROM THE
NORTHEAST TO MORE EASTERLY. THIS WIND SHIFT, COMBINED WITH
PERSISTENT ABOVE-NORMAL MOISTURE LEVELS AND RELATIVELY STEEP MID-
LEVEL LAPSE RATES, WILL MAINTAIN THE POTENTIAL FOR SCATTERED TO
NUMEROUS SHOWERS ACROSS THE REGION. THE BEST CHANCE FOR CONVECTION
REMAINS DURING THE AFTERNOON ACROSS INTERIOR AND WESTERN PUERTO
RICO. HOWEVER, OCCASIONAL PASSING SHOWERS MAY ALSO AFFECT THE U.S.
VIRGIN ISLANDS AND EASTERN MUNICIPALITIES DURING THE MORNING HOURS.
BY WEDNESDAY, THE INFLUENCE OF A DEVELOPING SURFACE TROUGH OVER
HISPANIOLA AND A BROAD HIGH-PRESSURE SYSTEM OVER THE CENTRAL
ATLANTIC WILL RESULT IN A SOUTHEAST WIND FLOW ACROSS THE REGION.
THIS SHIFT WILL INTRODUCE EVEN WARMER AND MORE HUMID CONDITIONS. THE
SOUTHEASTERLY FLOW WILL PUSH TROPICAL MOISTURE, INCREASING THE
POTENTIAL FROM AN INCREASE IN THE COVERAGE OF SHOWERS AND ISOLATED
THUNDERSTORMS. ONCE AGAIN, THE AFTERNOON HOURS WILL BE THE MOST
FAVORABLE FOR CONVECTIVE DEVELOPMENT, PARTICULARLY ACROSS INTERIOR
AND NORTHWESTERN PUERTO RICO. RESIDENTS AND VISITORS SHOULD REMAIN
ALERT FOR PERIODS OF LOCALLY HEAVY RAINFALL AND PONDING OF WATER IN
POOR DRAINAGE AREAS.
LONG TERM...THURSDAY THROUGH MONDAY
THE OVERALL FORECAST SCENARIO REMAINS CONSISTENT WITH THE PREVIOUS
DISCUSSION. ON THURSDAY, WINDS WILL WEAKEN AS A POLAR TROUGH
APPROACHES FROM THE WESTERN ATLANTIC. AT THE SAME TIME, ENHANCED
MOISTURE FROM THE CARIBBEAN WILL MOVE OVER THE REGION, DRIVEN BY A
SOUTHEASTERLY WIND FLOW. THESE FEATURES WILL SUPPORT THE DEVELOPMENT
OF SHOWERS AND THUNDERSTORMS, PARTICULARLY ACROSS THE INTERIOR,
WESTERN, AND NORTHERN PORTIONS OF PUERTO RICO DURING THE AFTERNOON
AND EARLY EVENING HOURS. THE IMPACTS ASSOCIATED WITH THIS WEATHER
PATTERN WILL BE THE URBAN AND SMALL STREAM FLOODING, RAPID RIVER
RISES, MUDSLIDES, AND FREQUENT LIGHTNING ASSOCIATED WITH
THUNDERSTORM ACTIVITY. FRIDAY WILL BRING SIMILAR CONDITIONS,
ALTHOUGH WINDS ARE FORECAST TO GRADUALLY VEER TOWARD THE EAST. THE
APPROACHING TROUGH WILL BE ACCOMPANIED BY A COLD FRONT, WHICH IS
EXPECTED TO MOVE INTO THE AREA BY SATURDAY. AS THE FRONT CROSSES THE
ISLANDS, WINDS WILL SHIFT TO THE NORTHEAST, CONTINUING TO SUPPORT
MOISTURE IN SOME AFTERNOON CONVECTION, ESPECIALLY OVER THE
CORDILLERA CENTRAL. WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS
REMAIN LIKELY DURING THIS PERIOD. BY SUNDAY INTO MONDAY, A DRIER AND
COOLER AIR MASS IS FORECAST TO MOVE INTO THE REGION IN THE WAKE OF
THE FRONT. THIS TRANSITION WILL BRING BREEZY NORTHEAST WINDS, LOWER
HUMIDITY, AND REDUCED RAIN CHANCES, SIGNALING A RETURN TO MORE
STABLE AND SEASONABLE WEATHER CONDITIONS.
OVERALL, UNSETTLED WEATHER CONDITIONS ARE EXPECTED TO PERSIST ACROSS
THE LOCAL ISLANDS THROUGH AT LEAST SATURDAY, WITH GRADUAL
IMPROVEMENT ANTICIPATED LATE IN THE WEEKEND AND INTO EARLY NEXT WEEK.
AVIATION
(06Z TAFS)
VFR TO MVFR CONDITIONS WILL BE PRESENT ACROSS THE TAF SITES DURING
THIS PERIOD. TSRA AND SHRA ARE EXPECTED ACROSS TJPS AND TJBQ AT
14/15Z TO 14/20Z, RESULTING IN A LOWER FLYING CEILING AND REDUCED
VIS IN THE TAF SITE AND THE VICINITY OF MOST SITES. WINDS WILL
REMAIN FROM THE NE AT 15 MPH, WITH GUSTY WINDS NEAR THE SHOWERS.
MARINE
A HIGH PRESSURE SYSTEM BUILDING OVER THE WESTERN ATLANTIC WILL
PROMOTE MODERATE TO LOCALLY FRESH EAST TO NORTHEAST WINDS OVER THE
NEXT FEW DAYS. THIS SAME FEATURE WILL PUSH THE REMNANTS OF A FRONTAL
BOUNDARY ACROSS THE REGION, LEADING TO INCREASED SHOWERS AND
THUNDERSTORMS. AFTERNOON CONVECTION WILL ALSO AFFECT PORTIONS OF THE
COASTAL WATERS. ANY THUNDERSTORM ACTIVITY WILL LIKELY GENERATE
LOCALLY HAZARDOUS MARINE CONDITIONS FOR SMALL CRAFT.
BEACH FORECAST
LIGHT WINDS WILL MAINTAIN THE RISK OF RIP CURRENTS LOW THROUGH
EARLY 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 SOUTHWESTERN COAST OF PUERTO
RICO.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
SHORT TERM/AVIATION...LIS
LONG TERM/MARINE/BEACH FORECAST...MMC
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