TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
650 AM EDT THU MAY 25 2023

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY
25/11UTC: A BROAD UPPER TROUGH SITS OVER THE SOUTHEAST
USA/CUBA/BAHAMAS...REFLECTING VERY WELL INTO THE MID-LEVELS. THIS
MEANS THAT A MID-LEVEL RIDGE EXTENDS OVER THE EASTERN CARIBBEAN.
ON THURSDAY MORNING...THE RIDGE CENTERED OVER NORTHEAST VENEZUELA
AND EXTENDED AN AXIS NORTH INTO THE MONA PASSAGE/WESTERN PUERTO
RICO. THE STRENGTHENING RIDGE IS STARTING TO BUILD A CAP...YET THE
CAP IS WEAK AND ELEVATED...SITTING NEAR 600 HPA ACCORDING TO THE
SAN JUAN SOUNDING. THE TRADES ARE WEAK AND FROM THE SOUTH.
AVAILABLE MOISTURE IS STILL HIGH. THE MOIST PLUME THAT HAS BEEN
SITTING EAST OF THE VI IS STILL PRESENT AND SHOWS VALUES OVER 50MM
OF PRECIPITABLE WATER IN THE EASTERN VI...WHILE 45-48MM ARE
PRESENT OVER PUERTO RICO.

GIVEN THE CURRENT DEVELOPING STAGNANT PATTERN IN THE SOUTHEAST US
AND NORTHERN CARIBBEAN...THERE IS MODEL AGREEMENT ON THE MID-LEVEL
RIDGE EXTENDING OVER THE EASTERN CARIBBEAN THROUGH THE FORECAST
CYCLE. THE RIDGE...HOWEVER...IS NOT EXPECTED TO BE TO STRONG AND
DEVELOP A SIGNIFICANT CAP...WHICH WILL ALLOW FOR AFTERNOON
DEVELOPMENT ON A DAILY BASIS. VARIABILITY IN PRECIPITATION WILL BE
LARGELY SENSITIVE TO AVAILABLE MOISTURE. INITIALLY...LARGER VALUES
ARE EXPECTED IN AREAS EAST OF THE VI ASSOCIATED WITH THE 45-50+ MM
MOIST PLUME. MODELS ALSO AGREE WELL ON ADVECTING THIS PLUME BACK
WEST INTO THE ISLANDS ON SATURDAY AND SUNDAY...EXITING WEST INTO
HISPANIOLA BY MONDAY. THIS WILL FAVOR A PEAK IN PRECIPITATION IN
THE VI ON SATURDAY...WHEN EXPECT SCATTERED MAXIMA OF 0.2-0.4
INCHES. IN PUERTO RICO...THE COVERAGE AND ACCUMULATIONS FROM
AFTERNOON CONVECTION WILL ALSO INCREASE ON SATURDAY AND PEAK ON
SUNDAY. ON SATURDAY...EXPECT MAXIMA OF 0.75-1.25 INCHES IN
NORTHWEST PUERTO RICO...WHILE ON SUNDAY EXPECT MAXIMA OF 1.25-2
INCHES. MUCH DRIER CONDITIONS ARE EXPECTED ON MONDAY AS A DRIER
AIR MASS MOVES IN FROM THE EAST.

IN THE MEAN TIME...EXPECT AFTERNOON CONVECTION TO CLUSTER IN
NORTH-CENTRAL AND NORTHWEST PUERTO RICO ON THURSDAY AND FRIDAY. ON
THURSDAY...EXPECT MAXIMA OF 0.75-1.25 IN...INCLUDING A POTENTIAL
FOR EXTENDING INTO THE SAN JUAN METRO. ON FRIDAY...EXPECT A
DECREASE TO 0.5-0.75 INCHES.

GALVEZ...WPC (USA)