376
FXCA20 KWBC 191237
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
836 AM EDT FRI MAY 19 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY
19/12UTC: AN IMPORTANT UPPER TROUGH IS DEEPENING ACROSS FLORIDA
AND THE NORTHWEST BAHAMAS ON FRIDAY MORNING. TO THE EAST...A WEAK
MID-LEVEL RIDGE PATTERN EXTENDS OVER HISPANIOLA AND PUERTO RICO.
YET...THE CURRENT GRADUAL WEAKENING OF THE RIDGE IS FAVORING
INCREASED DESTABILIZATION OF THE COLUMN. THE SAN JUAN SOUNDING
SHOWS DEEP-LAYER CONVECTIVE INSTABILITY AND LARGE AMOUNTS OF
PRECIPITABLE WATER...NEARING 50MM. THE TRADES ARE FROM THE
SOUTHEAST WITH SPEEDS OF 10-15KT. SATELLITE IMAGERY WAS SHOWING
FAIR WEATHER IN MOST OF PUERTO RICO AND THE VI...WITH THE
EXCEPTION OF THE VI AND ESPECIALLY EASTERN PUERTO RICO.
THE SYSTEM OF INTEREST IS THE ROBUST UPPER TROUGH...FORECAST TO
PROPAGATE INTO THE NORTH-CENTRAL CARIBBEAN THROUGH SATURDAY.
STARTING ON SATURDAY...PROPAGATION IS FORECAST TO SLOW DOWN...AND
THE SYSTEM WILL MEANDER EASTWARD SLOWLY...TO EXIT THE NORTHEAST
CARIBBEAN LATE ON TUESDAY. SEVERAL SHORT WAVE VORTICES ARE
FORECAST TO ROTATE AROUND THE MAIN TROUGH...BUT UNCERTAINTIES IN
THE PRECISE TIMING AND STRUCTURE OF THESE CONTINUE ADDING
UNCERTAINTIES ON THE PRECISE DISTRIBUTION OF THE REGIONS OF
HEAVIEST PRECIPITATION. REGARDING MODEL AGREEMENT...THE GFS SEEMS
TO BE TO THE RIGHT OF THE GENERAL GUIDANCE IN TERMS OF RAINFALL.
WE ARE MORE TOWARDS WESTERN SOLUTIONS...WHICH SHOW THE MOST
WIDESPREAD PRECIPITATION DEVELOPING FROM SATURDAY AFTERNOON
THROUGH EARLY MONDAY. YET...NOTE THAT ASIDE FROM THE MAIN
EVENT...LOCALLY HEAVY AFTERNOON CONVECTION IS EXPECTED ON A DAILY
BASIS.
ON FRIDAY...EXPECT MAXIMA OF 2-2.5 INCHES IN NORTHWEST PUERTO
RICO...WHILE TRADE WIND CONVERGENCE FAVORS MAXIMA NEARING 1 INCH
IN EASTERN PUERTO RICO. ON SATURDAY...ENHANCED SOUTHEASTERLY
TRADES WILL LIMIT AFTERNOON CONVECTION TO FAR NORTHWEST PUERTO
RICO...WHERE EXPECT MAXIMA OF 2-2.5 INCHES. TRADE WIND CONVERGENCE
WILL FAVOR TO AN INCREASE IN MAXIMA ALONG EASTERN PUERTO RICO AND
THE WESTERN VI TO 1-1.25 INCHES. ON SUNDAY...EXPECT MODERATE
AMOUNTS DEVELOPING ALONG THE SOUTHERN COAST AND SLOPES OF PUERTO
RICO ENHANCED BY SOUTHERLY FLOW...WHERE EXPECT SCATTERED MAXIMA OF
0.75-1.25 INCHES. SIMILAR AMOUNTS ARE EXPECTED IN WESTERN AND
NORTHWESTERN PUERTO RICO. ELSEWHERE IN THE ISLAND EXPECT MAXIMA OF
0.25-0.75 INCHES. SOUTHERLY TRADES EXTABLISH ON MONDAY. AS A
DRYING STARTS FROM WEST TO EAST...EXPECT THE LARGEST AMOUNTS TO
CLUSTER IN AFTERNOON CONVECTION IN NORTHERN AND NORTHEAST PUERTO
RICO...AS WELL AS ALONG THE VI...WHERE EXPECT MAXIMA OF 0.75-1
INCH. YET...NOTE THAT SCATTERED CONVECTION IS STILL EXPECTED
ACROSS THE ENTIRETY OF PUERTO RICO...INCLUDING MAXIMA OF 0.2-0.3
INCHES ALONG THE SOUTHERN COAST INTO THE SOUTHERN SLOPES OF THE
CORDILLERA. ON TUESDAY...UNDER CONTINUED SOUTHERLY FLOW...EXPECT
MAXIMA CLUSTERING IN NORTHERN PUERTO RICO REACHING 1-1.25 INCHES.
GALVEZ/ACOSTA...WPC (USA)
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page