466
FXCA20 KWBC 151236
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
735 AM EST WED NOV 15 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI NOV 15/12UTC:
ON WEDNESDAY MORNING...A MID-LEVEL RIDGE CENTERS NEAR 20N 66W AND
EXTENDS OVER THE ENTIRE NORTHEAST CARIBBEAN. THE RIDGE HAS ONLY
MINOR IMPACTS IN STRENGTHENING THE TRADE WIND CAP...BUT ASSOCIATES
WITH PLENTY OF DRY AIR ABOVE 925 HPA. THIS IS FAVORING WIDESPREAD
FAIR WEATHER AND VERY LITTLE CLOUD COVER IN PUERTO RICO AND THE
VI. CONVERSELY...A DISORGANIZED TROPICAL DISCURBANCE IS PRESENT IN
THE WESTERN CARIBBEAN. THIS IS THE MAIN STORY IN THE REGION...AS
THE DISTURBANCE IS EXPECTED TO INTERACT WITH AN APPROACHING UPPER
TROUGH UNDER INCREASINGLY FAVORABLE MJO CONDITIONS FOR HEAVY
PRECIPITATION. AS THE TROUGH MOVES WEST...THIS WILL ORGANIZE A
MOIST PLUME FROM THE SOUTHWEST CARIBBEAN INTO THE GREATER
ANTILLES...THAT WILL LIKELY HIGHLIGHT PRECIPITATION IN PUERTO RICO
DURING THE LATE WEEKEND AND EARLY NEXT WEEK AS MOIST SOUTHERLY
FLOW INTERACTS WITH TERRAIN.
IN THE MEANTIME...THE MID-LEVEL RIDGE IS FORECAST TO REMAIN THE
DOMINANT FEATURE THROUGH FRIDAY. GIVEN NO STRONG CAP ASSOCIATED
WITH THIS FEATURE...EXPECT A FEW PERIODS WITH MODERATE
PRECIPITATION BUT VERY LIMITED COVERAGE DUE TO ENHANCED DRY AIR
ENTRAINMENT WHENEVER CONVECTION DEVELOPS INTO THE MID-TROPOSPHERE.
PRECIPITABLE WATER IS EXPECTED TO REMAIN LOW ON WEDNESDAY AND
THURSDAY...RANGING FROM 30 TO 35MM...WHICH WILL RESULT IN VERY
LIMITED COVERAGE OF PRECIPITATION AND LIGHT RAINFALL AMOUNTS.
MOISTURE IS FORECAST TO INCREASE BEFORE SUNRISE ON FRIDAY...WHICH
WILL RESULT IN AN INCREASE IN LATE NIGHT/EARLY MORNING SHOWERS IN
SOUTHEAST PUERTO RICO TO FAVOR MAXIMA REACHING 0.3 INCHES.
PRECIPITABLE WATER AMOUNTS THEN INCREASE TO 50MM ON FRIDAY AS
TROPICAL MOISTURE IS TRANSPORTED FROM THE SOUTH AND LARGE SCALE
ASCENT INCREASES. MOISTURE AVAILABILITY REACHES A PEAK LATE ON
SATURDAY INTO SUNDAY...WHEN IT IS FORECAST TO REACH AMOUNTS NEAR
60MM. NOTE THAT CONFIDENCE DECREASES STARTING SATURDAY...AS
GUIDANCE IS STILL STRUGGLING ON THE STRUCTURE AND EVOLUTION OF THE
MOIST PLUME.
IN TERMS OF PRECIPITATION...EXPECT A NOTICEABLE INCREASE STARTING
FRIDAY...WHEN EXPECT MAXIMA NEAR 1 INCH IN SOUTHEAST PUERTO RICO
THROUGH SATURDAY MORNING. ON SATURDAY...UNDER THE INFLUENCE OF
MOIST SOUTHERLY FLOW...EXPECT SCATTERED CONVECTION IN THE SOUTHERN
HALF OF PUERTO RICO ALL DAY. TO PRODUCE SCATTERED MAXIMA OF 0.5 TO
1 INCH...ALTHOUGH ISOLATED HIGHER AMOUNTS ARE POSSIBLE IN
SOUTH-CENTRAL PUERTO RICO/PONCE REGION. A PEAK IS EXPECTED ON
SUNDAY...WHEN AMOUNTS ARE FORECAST TO REACH 1-2 INCHES IN FAR
SOUTHWEST PUERTO RICO. ELSEWHERE IN WESTERN...CENTRAL AND
SOUTHEAST PUERTO RICO EXPECT MAXIMA IN THE 0.25-0.75 INCH
RANGE...WHILE IN THE VI EXPECT AMOUNTS IN THE 0.2-0.4 INCH RANGE.
IN SUMMARY...FIVE DAY TOTALS ARE FORECAST TO REACH 2-4 INCHES IN
MOST OF SOUTHERN PUERTO RICO...ACCUMULATING PARTICULARLY FROM
FRIDAY THROUGH SUNDAY.
GALVEZ...WPC (USA)
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