697
FXCA62 TJSJ 120758
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
358 AM AST SAT APR 12 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. THE HEAVIEST
ACTIVITY IS EXPECTED ACROSS NORTH, WEST AND THE INTERIOR OF PUERTO
RICO, BUT SHOWERS WILL ALSO REACH THE VIRGIN ISLANDS AND EASTERN
PUERTO RICO AT TIMES.
SHORT TERM...TODAY THROUGH MONDAY
CALM WEATHER CONDITIONS PREVAILED OVERNIGHT ACROSS THE ISLANDS. FEW
SHOWERS MOVED OVER THE U.S. VIRGIN ISLANDS AND PORTIONS OF EASTERN
PUERTO RICO, LEAVING MINIMAL ACCUMULATIONS. HOWEVER, SHOWERS AND
THUNDERSTORMS WERE OBSERVED OVER THE LOCAL ATLANTIC WATERS PRODUCING
FREQUENT LIGHTNING NORTHWEST OF AGUADILLA. LOWS WERE SEEN IN THE MID
AND UPPER 70S IN THE COASTAL AREAS OF THE ISLANDS, AND IN THE MID TO
UPPER 60S IN THE MOUNTAINS.
A COLD FRONT LOCATED OVER THE HISPANIOLA WILL CONTINUE TO APPROACH
PUERTO RICO AND THE U.S. VIRGIN ISLANDS OVER THE WEEKEND. THE
INTERACTION OF THE COLD FRONT AND A SURFACE HIGH PRESSURE OVER THE
EASTERN ATLANTIC WILL CONTINUE TO PROMOTE LIGHT TO MODERATE
SOUTHEASTERLY WINDS THROUGH SUNDAY. HOWEVER, ANOTHER SURFACE HIGH
PRESSURE EXITING THE EASTERN U.S. COAST WILL PUSH THE COLD FRONT
OVER THE LOCAL AREA BY LATE SUNDAY INTO MONDAY MORNING.
THE PRECIPITABLE WATER CONTENT WILL REMAIN ABOVE-NORMAL
CLIMATOLOGICAL VALUES (2.0 TO 2.2 INCHES) THROUGH EARLY NEXT WEEK.
THEREFORE, ACTIVE AFTERNOONS ARE ANTICIPATED WITH MODERATE TO HEAVY
RAINFALL, PARTICULARLY OVER THE NORTHWESTERN QUADRANT OF PUERTO
RICO. THUNDERSTORM ARE LIKELY AS WELL DURING THE PERIOD, PRODUCING
FREQUENT LIGHTNING OVER THE AREA. WITH THE EXPECTED ACTIVITY, THERE
IS AN ELEVATED POTENTIAL TO OBSERVE URBAN AND SMALL STREAM FLOODING,
AS WELL AS RAPID RIVER RISES AND MUDSLIDES.
A WARMER TREND IS EXPECTED TO CONTINUE NEXT WEEK WITH ABOVE-NORMAL
TEMPERATURES AT THE 925MB. HIGHS WILL BE IN THE UPPER 80S TO LOW 90S
ACROSS THE COASTAL AND URBAN AREAS, AND IN THE UPPER 70S TO MID 80S
IN THE MOUNTAINS AND HIGHER ELEVATIONS. HEAT INDICES WILL REACH THE
102 DEGREES FAHRENHEIT THIS WEEKEND OVER PORTIONS OF WESTERN AND
NORTH-CENTRAL PUERTO RICO. REMEMBER TO STAY HYDRATED, WEAR LIGHT
CLOTHES, AND TAKE BREAKS IN SHADED AREAS!
LONG TERM...TUESDAY THROUGH SATURDAY
A SURFACE HIGH PRESSURE WILL ROLL EASTWARD FROM THE WEST, FORCING
THE FRONTAL BOUNDARY TO LIE DOWN ACROSS THE REGION, AND THUS
PROVIDING PLENTY OF MOISTURE THROUGH MUCH OF THE FORECAST PERIOD.
AT THE SURFACE, A TROUGH WILL ALSO DEVELOP ON TUESDAY, WHILE
ANOTHER MID TO UPPER LEVEL TROUGH WILL APPROACH FROM THE WEST ON
WEDNESDAY AND THURSDAY. AS THESE SYSTEM INTERACT, YET ANOTHER
SURFACE TROUGH WILL DEVELOP NORTH OF THE REGION. ALL THIS
INSTABILITY AND MOISTURE WILL RESULT IN ACTIVE AFTERNOONS, WITH
SHOWERS AND THUNDERSTORMS DEVELOPING, MOSTLY ACROSS THE INTERIOR,
WESTERN AND NORTHERN PUERTO RICO. SOMETHING ELSE TO CONSIDER IS
THAT WINDS WILL BE MOSTLY FROM THE SOUTHEAST...ON TUESDAY, AROUND
10-15 MPH, AND SLOWING DOWN AFTER WEDNESDAY, BELOW 10 MPH. AFTER
A COUPLE DAYS OF RAIN, SOILS WILL BE SATURATED, AND RIVERS WILL BE
RUNNING HIGH. THEREFORE, THE RISK FOR URBAN FLOODING, RAPID RIVER
RISES, AND MUDSLIDES WILL INCREASE.
BY THE END OF THE WEEK, THE UNCERTAINLY INCREASE, MOSTLY BECAUSE
THE ECMWF MODEL SHOWS A DEEPER TROUGH REACHING THE REGION, BUT THE
GFS DOES NOT HAVE SUCH A DEFINE FEATURE. THE FORECAST WAS ADJUSTED
FOR THIS PERIOD, SHOWING HIGHER PROBABILITY OF PRECIPITATION AND
AMOUNT OF RAINFALL. AS IS USUAL, SHOWERS WILL REACH EASTERN
PUERTO RICO AND THE VIRGIN ISLANDS PERIODICALLY, BUT THE STRONGEST
ACTIVITY WILL IMPACT THE INTERIOR, WESTERN AND NORTHERN PORTIONS
OF PUERTO RICO.
AVIATION
(06Z TAFS)
MAINLY VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS ALL TERMINALS
THROUGH THE PERIOD. PASSING SHRA WILL AFFECT THE TJSJ, TIST AND TISX
AT TIMES. HOWEVER, SHRA/TSRA WILL AFFECT THE TJBQ AFT 12/17Z CAUSING
BRIEF MVFR CNDS WITH PERIODS OF REDUCED VISIBILITY AND LOW CEILINGS.
MNTN OBSC IS EXPECTED FOR ALONG THE CORDILLERA CENTRAL TODAY. WINDS
WILL PREVAIL FROM THE SE AT 8-15 KTS WITH STRONGER GUSTS, MAINLY
NEAR THE STRONGEST SHRA ACTIVITY.
MARINE
A COLD FRONT ACROSS THE WESTERN ATLANTIC WILL CONTINUE TO APPROACH
THE NORTHEASTERN CARIBBEAN OVER THE NEXT FEW DAYS. 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 AND PUSH THE FRONT OVER THE LOCAL AREA BY EARLY NEXT
WEEK. THIS WILL PROMOTE MODERATE TO FRESH NORTHEAST WINDS FROM
MONDAY NIGHT ONWARDS. SHOWER AND THUNDERSTORM ACTIVITY WILL DEVELOP
EACH DAY, MAINLY ACROSS THE ATLANTIC WATERS AND THE MONA PASSAGE.
BEACH FORECAST
THE RISK OF RIP CURRENTS IS MODERATE TODAY, BUT CONDITIONS WILL
CONTINUE TO IMPROVE THROUGH MONDAY. TUESDAY ONWARD, THE MODERATE
RIP CURRENT RISK FOR NORTHERN AND EASTERN PUERTO RICO WILL RETURN.
THE RIP CURRENT RISK WILL BE LOW FOR THE VIRGIN ISLANDS THROUGH
THE FORECAST PERIOD.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
SHORT TERM...GRS
LONG TERM....ERG
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