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FXCA20 KWBC 301429
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
929 AM EST THU JAN 30 2025
WEEKLY DISCUSSION FOR PUERTO RICO AND THE USVI JAN 30 14 UTC:
OVER THE NEXT SEVERAL DAYS...THE EXPECTED RAINFALL PATTERN WILL
MOSTLY AFFECT EASTERN PUERTO RICO (PR) AND THE NORTHERN U.S.
VIRGIN ISLANDS (USVI)...WITH THE EXCEPTION OF TODAY...WHERE
CENTRAL TO SOUTHWESTERN PR COULD OBSERVE SOME SHOWERS AS A LOW
LEVEL TROUGH PASSES THROUGH THE AREA. THE 5-DAY RAINFALL FORECAST
IS THAT EASTERN AND NORTHEASTERN PR WOULD OBSERVE NEAR 2 INCHES OF
RAIN DUE TO THE ACCUMULATION OF DAILY RAINFALL...WHILE CENTRAL TO
SOUTHWESTERN PR COULD OBSERVE OVER 1.5 INCHES MAINLY DUE TO THE
RAINFALL EXPECTED THIS AFTERNOON. THE NORTHERN USVI ARE FORECAST
AROUND AN INCH OF RAIN AND ST. CROIX AROUND A HALF AN INCH OVER
THE NEXT 5 DAYS.
IN THE UPPER LEVELS...CURRENTLY THERE IS A RIDGE OVER PR...AND AN
UPPER TROUGH WILL MOVE INTO THE LEEWARDS BY THIS FRIDAY. THE UPPER
TROUGH AXIS WILL REMAIN OVER THE LEEWARDS THIS WEEKEND...THOUGH IT
WILL DRIFT SOUTH SLIGHTLY INTO THE WINDWARD ISLANDS BY SUNDAY. THE
UPPER TROUGH WILL WEAKEN EARLY IN THE WORKWEEK...WHILE UPPER LEVEL
CONFLUENCE AND CONVERGENCE MAY BE OBSERVED OVER THE LOCAL
ISLANDS...CAUSING SOME SUBSIDENCE ALOFT AS SUGGESTED BY THE LATEST
GUIDANCE. IN THE MID LEVELS THERE IS ALSO A RIDGE OF HIGH PRESSURE
OVER THE LOCAL ISLANDS AND A MID LEVEL TROUGH TO THE EAST OF THE
LESSER ANTILLES. BY THIS WEEKEND...THERE MAY BE SOME SPEED
DIVERGENCE IN THE MID LEVELS OVER THE LOCAL ISLANDS AS CONFLUENT
WINDS FROM THE NORTHEAST BECOME STRONGER SOUTH OF PR/USVI. THE MID
LEVEL WINDS WILL LIGHTEN UP EARLY NEXT WORKWEEK WHILE MID LEVEL
CONVERGENCE AND SUBSIDENCE IS THEN EXPECTED OVER THE LOCAL ISLANDS.
IN THE LOW LEVELS...A COLD FRONT IS LOCATED TO THE NORTHEAST OF
THE NORTHEAST CARIBBEAN...WHILE A LOW LEVEL TROUGH IS PRESENT TO
THE EAST OF THE LOCAL ISLANDS. THIS LOW LEVEL TROUGH WILL SLOWLY
MOVE WEST AND WILL PASS THE LOCAL ISLANDS TODAY INTO VERY EARLY
FRIDAY MORNING. THIS WILL HAVE AN IMPACT IN THE SHOWER DEVELOPMENT
EXPECTED TODAY...AS THE MOISTURE CONVERGENCE IN THE LOW LEVELS
ASSOCIATED WITH THE TROUGH...WILL COMBINE WITH THE DIURNAL HEATING
AND THE GENERAL WIND FLOW TO ENHANCE THE POSSIBILITY OF SHOWERS
ACROSS CENTRAL TO SOUTHWESTERN PR THIS AFTERNOON...WHILE OTHER
AREAS OBSERVE BRIEF SHOWERS. THE GENERAL WIND FLOW WILL BE FROM
THE ENE TODAY AND TONIGHT...THEN IT WILL BECOME MAINLY EASTERLY AS
A SFC HIGH PRESSURE MOVES INTO THE WESTERN ATLANTIC.
AFTER THE LOW LEVEL TROUGH PASSES...A TRADE WIND INVERSION WILL
DOMINATE THE LOCAL AREA FOR FRIDAY AFTERNOON INTO SATURDAY. THIS
INVERSION WILL ERODE ON SUNDAY BUT A WEAK INVERSION WILL RETURN ON
MONDAY ONWARD. THE AVAILABLE MOISTURE WILL BE FLUCTUATING BETWEEN
BRIEF MOMENTS OF ABOVE NORMAL MOISTURE AND NEAR TO BELOW NORMAL
MOISTURE. THE MID LEVEL RELATIVE HUMIDITY WILL ALSO FLUCTUATE
RAPIDLY. FOR THAT REASON...SOME DAYS WILL HAVE MORE RAINFALL THAN
OTHERS...BUT IN GENERAL THE RAINFALL PATTERN WILL BE SIMILAR EACH
DAY FROM FRIDAY ONWARD. AT THIS TIME...SUNDAY INTO VERY EARLY
MONDAY APPEARS TO BE THE WETTEST DAY FOR NORTHEASTERN PR...WHILE
TODAY IS EXPECTED TO BE THE WETTEST DAY FOR CENTRAL TO
SOUTHWESTERN PR AND POSSIBLY THE USVI AS THE LOW LEVEL TROUGH
PASSES THROUGH.
ALAMO...WPC(USA)
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