TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
843 AM EDT TUE SEP 26 2023

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI SEP 26/12UTC:
AVAILABLE MOISTURE WILL GRADUALLY DECREASE TODAY...REACHING BELOW
NORMAL LEVELS BY THIS EVENING...THEN REMAINING NEAR NORMAL THROUGH
THE REST OF THE WORKWEEK. PRECIPITABLE WATER WILL BE NEAR 1.9
INCHES THIS MORNING...DECREASING TO AROUND 1.6 INCHES BY THE EARL
EVENING HOURS...THEN NEAR 1.7 TO 2.0 INCHES FROM WEDNESDAY MORNING
THROUGH FRIDAY. IN TERMS OF RAINFALL COVERAGE OVER THE AREA...A
TYPICAL PATTERN OF AFTERNOON SHOWERS ACROSS WESTERN PR AND
SCATTERED SHOWERS OVER EASTERN PR AND THE USVI IS EXPECTED EACH
DAY THIS WEEK. IN THIS CASE...SINCE THERE ARE EAST NORTHEAST WINDS
EXPECTED...THE AFTERNOON CONVECTION IN PR...WILL BE MAINLY ACROSS
THE SOUTHWEST QUADRANT OF THE ISLAND. THE HI-RES MODEL GUIDANCE IS
A BIT MORE AGGRESSIVE WITH THE RAINFALL TOTALS...WHICH IS TO BE
EXPECTED CONSIDERING THAT SMALL SCALE FEATURES WILL PLAY A ROLE IN
THE SHOWER DEVELOPMENT...SUCH AS SEA BREEZE CONVERGENCE.
THEREFORE...FOR TODAY...THE HIGHEST AMOUNTS OF RAIN ARE FORECAST
ACROSS SOUTHWESTERN PR...WHILE ISOLATED SHOWERS ARE FORECAST
ACROSS THE USVI AND EASTERN PR.  A SIMILAR RAINFALL PATTERN IS
EXPECTED ON WEDNESDAY...BUT WITH SLIGHTLY MORE RAINFALL COVERAGE
AND MORE SIGNIFICANT RAIN FOR NORTHEAST PR AND THE USVI AS BIT OF
MOISTURE IS ADVECTED IN.

IN TERMS OF RAINFALL AMOUNTS...THE ACTIVITY EXPECTED THIS
AFTERNOON COULD PRODUCE ABOUT AN INCH OF RAIN OVER SOUTHWESTERN
PR...BUT HIGHER ISOLATED AMOUNTS ARE POSSIBLE. THEN WEDNESDAY
WOULD BE A BIT WETTER...WITH OVER 1.5 INCHES ACROSS SOUTHWEST PR
IN THE FORECAST...THEN AROUND 0.75 INCHES ARE FORECAST FOR
NORTHEASTERN PR...WHILE THE USVI ARE FORECAST TO OBSERVE AROUND A
QUARTER OF AN INCH OF RAIN. DRIER CONDITIONS ARE FORECAST FOR
THURSDAY ONWARD...BUT UNCERTAINTY STARTS TO INCREASE TOWARDS THE
LATTER PART OF THE FORECAST PERIOD. THE LATEST MODEL GUIDANCE HAS
CHANGED SIGNIFICANTLY WITH REGARDS TO THE TROPICAL STORM
PHILIPPE...AND THE FORECAST BY THE NATIONAL HURRICANE CENTER HAS
PHILIPPE TO THE NORTHEAST OF PR/USVI...WHICH WILL HAVE AN IMPACT
ON THE LOCAL WEATHER.

THE 5-DAY RAINFALL TOTAL IS FORECAST TO BE AROUND 3 INCHES ACROSS
THE SOUTHWESTERN SECTIONS OF PR...NORTH EASTERN PR IS FORECAST
AROUND 1.5 INCHES...WHILE THE USVI IS FORECAST 0.50 TO 1 INCH.

ALAMO/ACOSTA...WPC (USA)