204
FXCA20 KWBC 151220
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
820 AM EDT WED MAR 15 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAR
15/12UTC: A MID-UPPER RIDGE CONTINUE EXTENDING OVER THE SOUTHERN
CARIBBEAN...WHICH CONTINUES TO SUSTAIN WESTERLY FLOW IN THE UPPER
TROPOSPHERE DOWN TO 700 HPA. A TRADE WIND CAP IS STILL PRESENT
NEAR 650 HPA...ALTHOUGH IT HAS WEAKENED SOME WITH RESPECT TO
YESTERDAY. OF RELEVANCE...A SURFACE FRONT EXTENDS ACROSS THE
CENTRAL BAHAMAS...THE FLORIDA STRAIT AND CENTRAL GULF OF MEXICO.
THIS SYSTEM IS FORECAST TO ACCELERATE AND CROSS PUERTO RICO ON
THURSDAY EVENING. IN THE MEAN TIME...SATELLITE IMAGERY SHOWS CLOUD
CLUSTERS OVER THE WESTERN VI. THE SAN JUAN RADAR INDICATES
MODERATE PRECIPITATION OCCURRING IN THESE CLOUD CLUSTERS GIVEN A
DEEP MOIST LAYER AND A MAXIMA IN PRECIPITABLE WATER THAT IS
NEARING 1.6 INCHES. THE TRADES ARE WEAK AND FROM THE
SOUTHEAST...WHICH IS LEADING TO SLOW MOVING CONVECTION THIS
MORNING. THIS ENVIRONMENT WILL ALLOW FOR ANOTHER ROUND OF MODERATE
CONVECTION THIS AFTERNOON IN INTERIOR PORTIONS OF NORTHWEST PUERTO
RICO...WHERE EXPECT MAXIMA NEARING 1 INCH.
THE SYSTEM OF INTEREST CONTINUES TO BE THE SURFACE FRONT. IT IS
STILL FORECAST TO MOVE SOUTHWARD VERY RAPIDLY...CROSSING THE
ISLANDS FROM NORTHWEST TO SOUTHEAST ON THURSDAY EVENING. ALTHOUGH
THE SYSTEM IS FORECAST TO CROSS THE ISLANDS VERY RAPIDLY...IT
ARRIVES WITH UNSEASONABLY LARGE VALUES OF AVAILABLE MOISTURE AND
ENHANCED UPPER DIVERGENCE IN THE BASE OF A POTENT UPPER TROUGH.
THIS WILL FAVOR MODERATE PRECIPITATION ON THURSDAY AFTERNOON AND
EVENING...INCLUDING THE RISK FOR THUNDERSTORMS. EXPECT THE LARGEST
AMOUNTS CLUSTERING IN NORTHEAST PUERTO RICO...WHERE EXPECT
ACCUMULATIONS OF 0.5-1 INCH...ALTHOUGH ISOLATED MAXIMA OF 1-1.5
INCHES IS POSSIBLE IN REGIONS OF OROGRAPHIC ENHANCEMENT. IN THE VI
EXPECT GENERALLY MAXIMA OF 0.3-0.5 INCHES...AS IN THE NORTHWEST
COAST OF PUERTO RICO. THE POST FRONTAL AIR MASS SETS IN ON EARLY
HOURS OF FRIDAY...ACCOMPANIED BY FAST 15-20KT NORTHEASTERLY
TRADES. THESE WILL MAINTAIN A COLD ADVECTIVE PATTERN ON FRIDAY
LEADING TO INTERMITTENT LIGHT CONVECTION ACROSS MOST OF NORTHERN
AND NORTHEAST PUERTO RICO TO PRODUCE LIGHT ACCUMULATIONS. THE
WINDS SHIFT TO EASTERLIES ON SATURDAY...PERSISTING ON SUNDAY. THIS
WILL DEVELOP THE LARGEST ACCUMULATIONS IN EASTERN PUERTO RICO DUE
TO TRADE WIND CONVERGENCE. SATURDAY LOOKS AS THE DRIEST DAY...BUT
ON SUNDAY AN INCREASE IN MOISTURE DUE TO THE REMNANTS OF THE FRONT
WILL FAVOR AN INCREASE IN MAXIMA TO 0.2-0.3 INCHES IN EASTERN
PUERTO RICO.
ACOSTA/GALVEZ/ALAMO...WPC (USA)
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