336
FXCA20 KWBC 101147
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
747 AM EDT MON APR 10 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APR
10/12UTC: A LARGE UPPER TROUGH EXTENDS OFF THE EAST COAST OF THE
UNITED STATES...WITH ITS BASE INTO THE NORTHWEST BAHAMAS. THIS IS
INTERACTING WITH A SURFACE FRONT IN THE REGION...FAVORING THE
DEVELOPMENT OF SCATTERED DEEP CONVECTION IN AREAS NORTH OF 25N AND
BETWEEN 72W AND 62W. LOW SURFACE PRESSURES BETWEEN THE BAHAMAS AND
BERMUDA ASSOCIATE WITH SOUTHERLY TRADES ACROSS PUERTO RICO AND THE
VI ON MONDAY MORNING. OVER THE ISLANDS...A WEAK MID-UPPER SHORT
WAVE TROUGH IS PROPAGATING EASTWARD...WHILE EXTENDING ALONG 25N
67W INTO EASTERN PUERTO RICO ON MONDAY MORNING.
NEVERTHELESS...PRECIPITABLE WATER NEAR OR BELOW 40MM AND LIMITED
VENTILATION ARE LIMITING THE DEVELOPMENT OF CONVECTION THIS
MORNING. SATELLITE IMAGERY SHOWS VERY ISOLATED CONVECTION IN
PORTIONS OF SOUTHERN PUERTO RICO AND THE VI...AND THE SAN JUAN
RADAR SHOWS ISOLATED SHOWERS MOSTLY OVER OPEN WATERS OFF THE COAST
OF SOUTHERN PUERTO RICO AND NEAR NAGUABO.
AS THE WEEK PROGRESSES...THE EASTERN CARIBBEAN IS FORECAST TO LIE
UNDER THE INFLUENCE OF THE SUBEQUATORIAL RIDGE IN NORTHERN SOUTH
AMERICA. THE UPPER RIDGE PATTERN WILL BE IN PHASE WITH A MID-LEVEL
RIDGE...FORECAST TO MEANDER FROM VENEZUELA/WINDWARD ISLANDS ON
MONDAY TO THE WESTERN CARIBBEAN BY FRIDAY. ALTHOUGH THE TRADE WIND
CAP IS FORECAST TO REMAIN WEAK THROUGH THE FORECAST CYCLE ALLOWING
FOR VERTICAL DEVELOPMENT IN AFTERNOON CONVECTION...ENHANCED
SINKING MOTION WILL LIKELY LIMIT THE COVERAGE OF AFTERNOON
CONVECTION AND ASSOCIATED PRECIPITATION. THE FRONT IS FORECAST TO
APPROACH THE REGION ON THURSDAY...BUT IT IS FORECAST TO STALL WELL
TO THE NORTH OF THE ISLANDS. A POTENTIAL SHORT-LIVED SHEAR LINE IS
EXPECTED TO DEVELOP ON THURSDAY MORNING. THE ASSOCIATED
NORTHEASTERLY TRADES ARE FORECAST TO ENTER THE ISLANDS DURING THE
DAY ON THURSDAY...TO FAVOR AN INCREASE IN THE COVERAGE OF TRADE
WIND SHOWERS ON THURSDAY AND FRIDAY. YET...UNDER THE INFLUENCE OF
THE MID-LEVEL RIDGE AND VERTICAL WIND SHEAR...EXPECT LIGHT
ACCUMULATIONS.
ON MONDAY...AFTERNOON CONVECTION WILL LIKELY CLUSTER IN NORTHERN
PUERTO RICO WHERE EXPECT MAXIMA OF 0.2-0.35 INCHES. AS TRADES
START BACKING AND BECOME SOUTH EASTERLIES ON TUESDAY AND
WEDNESDAY...EXPECT AREAS OF AFTERNOON CONVECTION TO RELOCATED TO
INTERIOR PORTIONS OF NORTHERN AND NORTHWEST PUERTO RICO...WHERE
EXPECT ISOLATED MAXIMA OF 0.4-0.6 INCHES. AS NORTHEASTERLY TRADES
DEVELOP ON THURSDAY...EXPECT AN INCREASE IN THE COVERAGE OF
PRECIPITATING TRADE WIND CONVECTION...TO PRODUCE SCATTERED MAXIMA
OF 0.05-0.15 INCHES ALONG NORTHERN PUERTO RICO AND THE VI...AND
MAXIMA OF 0.2-0.3 INCHES IN THE WESTERN CORDILLERA AND SOUTHWEST
PUERTO RICO. ON FRIDAY...EASTERLY TRADES RETURN...TO FAVOR MAXIMA
OF 0.1-0.15 INCHES IN EASTERN PUERTO RICO...AND AFTERNOON MAXIMA
OF 0.2-0.4 INCHES IN THE CENTRAL AND WESTERN CORDILLERA.
GALVEZ/ALAMO...WPC (USA)
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