375
FXCA20 KWBC 131212
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
811 AM EDT MON MAR 13 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAR
13/12UTC: WESTERLY FLOW IS PRESENT IN THE MID AND UPPER
LEVELS...AS THE SUBEQUATORIAL RIDGE IS WELL ESTABLISHED IN
NORTHERN SOUTH AMERICA AND A MID-LEVEL RIDGE HAS FORMED OVER THE
SOUTHERN CARIBBEAN. IN THE LOWER LEVELS...THE TRADES CONTINUE TO
BE WEAK AND FROM THE EAST. PRECIPITABLE WATER VALUES ARE LOW...AND
THEY RANGE BETWEEN 1 AND 1.2 INCHES. SATELLITE IMAGERY SHOWS VERY
LITTLE CLOUDINESS OVER PUERTO RICO AND THE VI ON MONDAY MORNING.
OF RELEVANCE FOR LATER IN THE CYCLE...A SURFACE FRONT EXTENDS
ALONG THE SOUTHEAST COAST OF THE USA INTO THE NORTHERN GULF OF
MEXICO. THIS FRONT WILL MOVE SLOWLY THROUGH TUESDAY...BUT AS IT
INTERACTS WITH A STRONG UPPER TROUGH MOVING INTO THE EASTERN USA
FROM THE GREAT LAKES...THIS WILL ACCELERATE THE FRONT RAPIDLY ON
WEDNESDAY AND THURSDAY. MODELS FORECAST THE FRONT RAPIDLY CROSSING
PUERTO RICO AND THE VI LATE ON THURSDAY INTO EARLY HOURS OF
FRIDAY...PRODUCING A PEAK IN PRECIPITATION.
IN TERMS OF THE EVOLUTION...MONDAY LOOKS DRY GIVEN LIMITED AMOUNTS
OF AVAILABLE MOISTURE OVER THE ISLANDS AND NO SIGNIFICANT
ATMOSPHERIC DYNAMICS FOR ASCENT. A MOIST PLUME IS LINGERING IN THE
CENTRAL CARIBBEAN...REMNANT FROM LAST WEEK'S FRONT. THIS MOIST
PLUME IS FORECAST TO MEANDER NORTHWARD...ARRIVING INTO THE ISLANDS
ON TUESDAY. THIS WILL RESULT IN AN INCREASE IN PRECIPITATION.
MORNING CONVECTION IS EXPECTED ALONG THE SOUTH COAST TO SUSTAIN
MAXIMA OF 0.2-0.4 INCHES. AFTERNOON CONVECTION WILL CLUSTER IN
INTERIOR PORTIONS OF NORTHWEST PUERTO RICO...WHERE EXPECT MAXIMA
OF 1-1.5 INCHES. A SIMILAR DISTRIBUTION IS EXPECTED ON
WEDNESDAY...ALTHOUGH MAXIMA IS EXPECTED TO DECREASE TO 0.1 INCHES
ALONG THE SOUTH COAST AND 0.5-1 INCH IN AFTERNOON CONVECTION IN
NORTHERN PUERTO RICO. THE FRONT ARRIVES LATE ON THURSDAY...BUT
PREFRONTAL ACTIVITY WILL FLARE UP IN THE AFTERNOON FAVORING
MODERATE AMOUNTS IN THE NORTHEASTERN HALF OF PUERTO RICO. EXPECT
TOTALS OF 0.5-1 INCHES ALONG THE NORTH AND EAST COAST/EAST
INTERIOR...ALTHOUGH ISOLATED VALUES OF 1-1.5 INCHES ARE POSSIBLE
IN COASTAL AREAS OF NORTHEAST PUERTO RICO AND TO A LESSER EXTENT
IN VIEQUES. MUCH DRIER CONDITIONS ARE EXPECTED ON FRIDAY...AS THE
DRY POST FRONTAL AIR MASS RAPIDLY SETS IN. ANY ACTIVITY WILL
CLUSTER IN NORTHERN PUERTO RICO IN THE FORM OF VERY LIGHT
INTERMITTENT SHOWERS ASSOCIATED WITH THE NORTHERLY LOW-LEVEL WINDS.
ACOSTA/GALVEZ...WPC (USA)
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