989
FXCA62 TJSJ 022026
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
426 PM AST SUN MAR 2 2025
SYNOPSIS
MOSTLY CLEAR SKIES WITH LITTLE OR NO RAIN ARE EXPECTED TO CONTINUE
OVERNIGHT AND MONDAY MORNING DUE TO A DRIER AIR MASS WITH
SUSPENDED SAHARAN DUST PARTICLES. THE ARRIVAL OF A PRE-FRONTAL
TROUGH AROUND MONDAY AFTERNOON WILL INCREASE THE POTENTIAL FOR
SHOWERS ACROSS THE ISLANDS. AN UPPER-LEVEL TROUGH WILL INCREASE
INSTABILITY, AND INTERACTING WITH THE INDUCED PRE-FRONTAL TROUGH
WILL RESULT IN SCATTERED TO NUMEROUS SHOWERS AND EVEN
THUNDERSTORMS THROUGH AT LEAST TUESDAY. ANOTHER MID TO UPPER-LEVEL
TROUGH WILL PROMOTE EXTEND THE UNSTABLE WEATHER PATTERN THROUGH
THE SECOND PART OF THE WORKWEEK.
SHORT TERM...TONIGHT THROUGH TUESDAY
PATCHES OF LOW-LEVEL MOISTURE, SURFACE TROUGHS, AND A WEAK SAHARAN
AIR LAYER (SAL) WILL CONTINUE TO MOVE OVER THE LOCAL AREA THROUGHOUT
THE SHORT-TERM PERIOD. THIS WILL LEAD TO HAZY SKIES DUE TO MINOR
CONCENTRATIONS OF SAHARAN DUST AND PASSING SHOWERS IN THE WINDWARD
AREAS OF THE ISLANDS DURING THE NIGHT AND EARLY MORNING HOURS. IN
THE AFTERNOONS, CONVECTION IS EXPECTED MAINLY OVER THE INTERIOR AND
WESTERN PUERTO RICO EACH DAY.
EAST TO SOUTHEAST WINDS, SOMETIMES BREEZY (12-18 KNOTS), WILL
PREVAIL THIS EVENING AS A SURFACE HIGH PRESSURE OVER THE CENTRAL
ATLANTIC MOVES FURTHER EAST, AND A COLD FRONT MOVES JUST NORTH OF
THE AREA FROM THE WESTERN ATLANTIC. HOWEVER, WINDS ARE EXPECTED TO
SHIFT EAST-NORTHEAST ON MONDAY WITH THE ARRIVAL OF A SURFACE
TROUGH FROM THE EAST. WIND SPEEDS WILL GENERALLY DECREASE IN
RESPONSE TO THE TROUGH AND THE PROXIMITY OF THE FRONT.
A WETTER AND MORE UNSTABLE WEATHER PATTERN IS FORECASTED FOR TUESDAY
ONWARDS. A MID TO UPPER-LEVEL TROUGH WILL APPROACH THE ISLANDS BY
TUESDAY. THIS WILL BE ACCOMPANIED BY A SEGMENT OF THE JET STREAM
REACHING THE ISLANDS, RESULTING IN COLDER 500 MB TEMPERATURES
(AROUND -8C) AND INCREASED INSTABILITY. THIS COULD ENHANCE THE
POTENTIAL FOR STRONGER AFTERNOON CONVECTION, WHICH MAY LEAD TO
ISOLATED THUNDERSTORMS. THE RISK OF EXCESSIVE RAINFALL (1-2 INCHES,
WITH LOCALLY HIGHER AMOUNTS) WILL INCREASE, PARTICULARLY OVER THE
INTERIOR AND NORTHWESTERN SECTIONS OF PUERTO RICO.
MAXIMUM TEMPERATURES ARE EXPECTED TO DROP BY 1-2 DEGREES THROUGH
TUESDAY ACROSS MOST OF PUERTO RICO AND THE US VIRGIN ISLANDS, EXCEPT
ALONG THE SOUTHERN COASTAL AREAS, WHERE TEMPERATURES WILL RANGE FROM
THE MID-80S TO NEARLY 90F.
LONG TERM...WEDNESDAY THROUGH SUNDAY
FROM PREVIOUS DISCUSSION
A SURFACE HIGH PRESSURE OVER THE CENTRAL ATLANTIC WILL MAINTAIN
THE TRADE WINDS FROM THE SOUTHEAST AT MODERATE SPEEDS. AT THE MID
TO UPPER LEVELS, THE AXIS OF THE TROUGH WILL BE POSITIONED JUST TO
THE NORTHEAST OF THE ISLANDS. EVEN THOUGH, SOME INSTABILITY WILL
REMAIN OVER THE ISLANDS, WITH MID-LEVEL TEMPERATURES A LITTLE
COOLER THAN NORMAL. A SURFACE REFLECTION OF THE TROUGH WILL ALSO
MOVE OVER THE ISLANDS, BRINGING SOME SHOWERS OVER THE VIRGIN
ISLANDS AND EASTERN PUERTO RICO. HOWEVER, THE STRONGEST SHOWERS
ARE EXPECTED FOR THE INTERIOR AND NORTHWEST OF PUERTO RICO, WHERE
THERE IS ALSO A CHANCE OF LIGHTNING.
BY THE END OF THE WEEK, THE WINDS WILL GAIN A SOUTHERLY COMPONENT
DUE TO A COLD FRONT THAT EXITS THE EASTERN COAST OF THE UNITED
STATES. AS THE FRONT APPROACHES, THE WINDS WILL BECOME LIGHT AND
VARIABLE. THE MOISTURE AND SHOWERS ASSOCIATED WITH THIS FRONT WILL
LIKELY REACH THE ISLANDS AS FRAGMENTED PATCHES OF CLOUDS, SO A
SIGNIFICANT INCREASE IN SHOWERS IS NOT EXPECTED. HOWEVER, WITH
LIGHT WINDS, ANY EPISODE OF RAIN THAT DEVELOPS WILL LIKELY LINGER,
RESULTING IN AN ELEVATED RISK OF URBAN AND SMALL STREAM FLOODING.
ADDITIONALLY, WITH THESE SOUTHERLY WINDS ON THURSDAY AND FRIDAY,
IT IS LIKELY THAT TEMPERATURES WILL FEEL ABOVE NORMAL, WITH HIGHS
IN THE UPPER 80S FOR COASTAL AREAS.
THE FORECAST IS A LITTLE MORE UNCERTAIN BY LATE SATURDAY AND
SUNDAY. THERE ARE DISCREPANCIES ON HOW MUCH MOISTURE WILL REACH
THE ISLANDS BY THEN. FOR NOW, A WETTER SOLUTION IS SHOWN, WITH A
40-50% CHANCE OF SHOWERS INCREASING ACROSS THE ATLANTIC WATERS,
THE NORTHERN AND EASTERN MUNICIPALITIES OF PUERTO RICO, AND ALSO
FOR THE VIRGIN ISLANDS.
AVIATION
(18Z TAFS)
TEMPO MVFR CONDS ARE POSSIBLE AT TJBQ THRU 02/22Z DUE TO LINGERING
SHRA. ALTHOUGH, MAINLY VFR CONDITIONS EXPECTED ACROSS ALL TERMINALS
THROUGH THE FORECAST PERIOD, TRADE WIND SHRA EN ROUTE FROM THE
WINDWARD TERMINALS UNDER 10-15 KT ESE WINDS MAY CAUSE SCT/BKN CIGS
BTW FL030-FL050, AND OCCASIONALLY LOWER THROUGH THE REST OF THE
EVENING AND EARLY MONDAY MORNING HOURS ACROSS THE USVI AND THE
EASTERN PR TERMINALS. HZ DUE TO MINOR CONCENTRATIONS OF SAHARAN DUST
WILL CONTINUE THROUGH THE PERIOD BUT VSBY WILL REMAIN P6SM.
MARINE
A FRONTAL BOUNDARY APPROACHING FROM THE WESTERN ATLANTIC WILL
SLOWLY LOOSEN THE PRESSURE GRADIENT ASSOCIATED WITH THE BROAD
SURFACE HIGH PRESSURE EXTENDING FROM THE EASTERN TO CENTRAL
ATLANTIC. THUS, EXPECT MODERATE TO LOCALLY FRESH EAST-SOUTHEAST
WINDS TONIGHT INTO TOMORROW. THEN, WINDS WILL TURN MODERATE,
MAINLY RETURNING FROM THE EAST TO NORTHEAST BY TUESDAY.
FURTHERMORE, AN INDUCED SURFACE TROUGH ASSOCIATED WITH THE
FRONTAL BOUNDARY WILL INCREASE THE RISK OF SHOWERS AND EVEN
THUNDERSTORMS ACROSS THE REGIONAL WATERS LATE MONDAY INTO TUESDAY.
BEACH FORECAST
THE RIP CURRENT RISK WILL CONTINUE FROM AGUADILLA TO FAJARDO, FROM
FAJARDO TO MAUNABO, AND TO SALINAS. ALSO, ST CROIX WILL HAVE A
MODERATE RISK OF RIP CURRENTS TONIGHT. AS WINDS WEAKEN, THE
MODERATE RISK WILL DROP TO LOW ALONG MOST OF THE LOCAL BEACHES IN
PUERTO RICO AND THE U.S. VIRGIN ISLANDS TOMORROW, EXCEPT FOR
NORTH-CENTRAL PR AND ST CROIX, WHERE WILL CONTINUE MODERATE.
REGARDLESS THE LOW RISK, LIFE-THREATENING RIP CURRENTS OFTEN
OCCUR IN THE VICINITY OF GROINS, JETTIES, REEFS, AND PIERS.
PLEASE, EXERCISE CAUTION.
SJU WATCHES/WARNINGS/ADVISORIES
PR...NONE.
VI...NONE.
AM...NONE.
SHORT TERM/AVIATION...DS
SYNOPSIS/LONG TERM/MARINE/BEACH FORECAST...CAM
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