TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
848 AM EDT WED SEP 27 2023

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI SEP 27/12UTC:
THE MAIN STORY IS THE POTENTIAL IMPACT OF TROPICAL STORM PHILIPPE
OVER PR/USVI THIS WEEKEND INTO EARLY NEXT WEEK. THE LATEST
FORECAST BY THE NATIONAL HURRICANE CENTER HAS PHILIPPE WEAKENING
GRADUALLY OVER THE NEXT FEW DAYS...GETTING CLOSER TO THE LOCAL
ISLANDS THIS WEEKEND...THOUGH THE FORECAST SUGGESTS IT WILL BE A
REMNANT LOW OR POST TROPICAL SYSTEM BY THEN. THE NATIONAL
HURRICANE FORECAST TRACK ON PHILIPPE IS CLOSER TO THE ECMWF MODEL
THAN THE GFS...THEREFORE THE RAINFALL FORECAST REFLECTS MORE
CONSIDERATION AND PREFERENCE FOR THE ECMWF MODEL. THE RAINFALL
AMOUNTS SUGGESTED BY THE ECMWF MODEL ARE GENERALLY UNDER 2 INCHES
FOR THE 48-HOUR PERIOD OF SUNDAY AND MONDAY...WITH THE HIGHER
AMOUNTS AFFECTING THE USVI...VIEQUES...CULEBRA AND SOME COASTAL
MUNICIPALITIES OF MAINLAND PR. THERE IS CONSIDERABLE UNCERTAINTY
IN THE RAINFALL FORECAST ASSOCIATED TO PHILIPPE...AND THE LATEST
FORECASTS BY THE NATIONAL HURRICANE CENTER SHALL BE MONITORED AND
CONSIDERED WITH EACH ISSUANCE.

FROM TODAY THROUGH SATURDAY...THE AVAILABLE MOISTURE WILL RANGE
BETWEEN 2.1 AND 1.7 INCHES...WHICH IS IN THE NORMAL RANGE FOR THE
DATE...BUT MOISTURE WILL INCREASE ON SUNDAY AS PHILIPPE
APPROACHES. THE RAINFALL COVERAGE TODAY AND THURSDAY WILL BE
FAIRLY TYPICAL...ISOLATED TO SCATTERED SHOWERS ACROSS THE USVI AND
EASTERN PR...WHILE AFTERNOON CONVECTION IS EXPECTED ACROSS THE
SOUTHWESTERN QUADRANT OF PR...SINCE THERE WILL BE ENE-NE WINDS
OVER THE AREA. THE LOCAL WINDS MAY WEAKEN BY FRIDAY INTO
SATURDAY...AND THE RAINFALL PATTERN IS EXPECTED TO FAVOR THE
NORTHEASTERN SECTORS OF PR AS WELL AS THE NORTHERN USVI

IN TERMS OF RAINFALL AMOUNTS...THE ACTIVITY EXPECTED THIS
AFTERNOON COULD PRODUCE OVER AN INCH OF RAIN OVER SOUTHWESTERN
PR...BUT HIGHER ISOLATED AMOUNTS ARE POSSIBLE...POSSIBLY NEAR 0.75
INCHES ACROSS NORTHEASTERN PR AND AROUND A QUARTER OF AN INCH FOR
THE USVI. THURSDAY WOULD BE SIMILAR...WITH A POSSIBILITY OF OVER
AN INCH OF RAIN ACROSS CENTRAL...WESTERN...AND SOUTHWESTERN
PR...THEN AROUND 0.25 INCHES ARE FORECAST FOR NORTHEASTERN
PR...WHILE THE USVI ARE FORECAST TO OBSERVE AROUND A TENTH OF AN
INCH OF RAIN. FRIDAY IS FORECAST TO HAVE AROUND 0.25 TO 0.5 INCHES
ACROSS NORTHERN AND EASTERN PR...AS WELL AS THE NORTHERN
USVI...BUT ST CROIX IS FORECAST TO OBSERVE UNDER 0.25 INCHES. FOR
THE WEEKEND...BASED ON THE LATEST GUIDANCE...A SIMILAR RAINFALL
PATTERN TO FRIDAY IS EXPECTED...BUT THE AMOUNTS ARE HIGHER WITH
MAX VALUES OF OVER A HALF AN INCH ON SATURDAY INTO SUNDAY...AND
NEAR AN INCH OF RAIN ON SUNDAY INTO MONDAY.

THE 5-DAY RAINFALL TOTAL IS FORECAST TO BE AROUND 3 TO 3.25 INCHES
ACROSS THE SOUTHWESTERN SECTIONS OF PR...NORTH EASTERN PR IS
FORECAST JUST UNDER 3 INCHES...WHILE THE USVI IS FORECAST 1.25 TO
2 INCHES.

ALAMO/ACOSTA...WPC (USA)