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FXCA20 KWBC 131221
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
720 AM EST FRI JAN 13 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN
13/12UTC: ON FRIDAY MORNING...A STRONG UPPER TROUGH OVER THE
NORTHEASTERN UNITED STATES IS SUSTAINING A PROGRESSIVE COLD FRONT
ACROSS CENTRAL FLORIDA AND INTO SOUTHERN MEXICO. THE FRONT IS
PROPAGATING RAPIDLY TO THE SOUTHEAST...AND IS FORECAST TO CROSS
THE ISLANDS FROM NORTHWEST TO SOUTHEAST ON SUNDAY. IN THE MEAN
TIME...SATELLITE AND RADAR INDICATE GENERALLY FAIR WEATHER
CONDITIONS ACROSS THE ISLANDS. ISOLATED SHOWERS WERE OCCURRING IN
EASTERN PUERTO RICO FROM SHALLOW TRADE WIND CONVECTION PROPAGATING
FROM THE EAST. THE EASTERLY TRADES ARE RESTORED...AND THEY HAVE
SPEEDS IN THE 15-20KT RANGE THROUGH 750 HPA. WESTERLIES CONTINUE
IN THE MID-AND UPPER TROPOSPHERE...WHICH WILL CONTINUE TO
INTERFERE WITH THE DEVELOPMENT OF ANY DIURNAL CONVECTION THAT
REACHES THESE LEVELS.
THE SYSTEM OF INTEREST IS THE FRONT PROPGATING RAPIDLY INTO THE
BASIN. THE SYSTEM IS FORECAST TO APPROACH THE MONA PASSAGE BEFORE
SUNRISE ON SUNDAY...WHEN PRECIPITATION SHOULD START DEVELOPING IN
PORTIONS OF NORTHWEST PUERTO RICO. THE FRONT ENTERS THE ISLAND
BETWEEN 15 AND 18 UTC ON SUNDAY...AND CLEARS THE VI BY
MIDNIGHT/FIRST HOURS OF MONDAY. ALTHOUGH THE SYSTEM CROSSES
RAPIDLY...ITS DYNAMICS ARE FORMIDABLE. GIVEN A STILL ACTIVE MJO
AND LARGE VALUES OF MOISTURE CONVERGENCE WE ARE LEANING TOWARDS
THE WETTER SOLUTIONS. UNDER THE CURRENT EXPECTED EVOLUTION...THE
LARGEST ACCUMULATIONS ARE LIKELY IN NORTH CENTRAL AND NORTHEAST
PUERTO RICO...INCLUDING THE SAN JUAN METRO AREA. WE EXPECT AMOUNTS
IN THE 1-2 INCHES RANGE IN NORTHCENTRAL AND NORTHEAST PUERTO
RICO...AND MAXIMA OF 0.75-1.25 INCHES IN EASTERN AND SOUTHEAST
PUERTO RICO. IN THE VI...THE LARGEST ACCUMULATIONS ARE EXPECTED IN
THE NORTHERN PORTIONS...WHERE SCATTERED AMOUNTS OF 0.5-1 INCH ARE
EXPECTED. AFTER THE FRONT PASSES...EXPECT GENERALLY FAIR WEATHER
CONDITIONS AND LITTLE PRECIPITATION WITH THE EXCEPTION OF NORTHERN
AND NORTHEAST PUERTO RICO...WHERE ENHANCED LOW-LEVEL CONVERGENCE
UNDER LIGHT NORTHEASTERLY TRADES WILL FAVOR LIGHT ACCUMULATIONS ON
EARLY MORNING HOURS THROUGH WEDNESDAY. HIGHER AMOUNTS ARE EXPECTED
IN SAINT CROIX...BUT THERE ARE STILL UNCERTAINTIES ON THE PRECISE
POSITION OF WHERE THE FRONT WILL STALL.
OTHER THAN THE PASSAGE OF THE FRONT ON SUNDAY...EXPECT GENERALLY
DRIER CONDITIONS THAN IN PREVIOUS DAYS. ON FRIDAY AND
SATURDAY...SOUTHEASTERLY AND SOUTHERLY TRADES WILL CLUSTER
AFTERNOON CONVECTION IN EXTREME NORTHWEST AND EXTREME NORTHERN
PUERTO RICO RESPECTIVELY. YET...LIMITED AMOUNTS OF AVAILABLE
MOISTURE...LIMITED ASCENT AND SHORT RESIDENCE TIMES OF DEVELOPING
CONVECTION WILL LIKELY LIMIT MAXIMA UNDER 0.25 INCHES.
GALVEZ/ACOSTA...WPC (USA)
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