007  
FXCA20 KWBC 231145  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
744 AM EDT TUE MAY 23 2023  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY  
23/12UTC: AN UPPER TROUGH CENTERS ON A LOW OVER THE NORTHERN VI.  
THE LOW IS HIGHLIGHTING INSTABILITY OVER A MOIST PLUME THAT  
EXTENDS MERIDIONALLY ACROSS THE VI AND EASTERN PUERTO RICO. THIS  
IS HIGHLIGHTING DEEP CONVECTION. GIVEN A BROAD SURFACE LOW EAST OF  
THE BAHAMAS...THE TRADES ARE FROM THE SOUSTH-SOUTHEAST. SATELLITE  
IMAGERY AND RADAR SHOW A BAND OF DEEP CONVECTION FLARING UP OVER  
AND OFF THE COAST OF SOUTHEAST AND EASTERN PUERTO RICO. SOME OF  
THIS CONVECTION IS RAPIDLY PROPAGATING NORTHWESTWARD...REACHING  
PORTIONS OF CENTRAL PUERTO RICO.  
 
A LARGE UPPER TROUGH IS DEEPENING ACROSS THE SOUTHEAST USA AND TO  
THE NORTH OF THE BAHAMAS. AS THIS TROUGH APPROACHES...IT WILL  
STIMULATE A NORTHEASTWARD PROGRESSION OF THE CURRENT UPPER LOW  
OVER THE VI. THE UPPER LOW IS FORECAST TO EXIT THE ISLANDS LATE ON  
TUESDAY...AND BY WEDNESDAY MORNING IT IS EXPECTED NEAR 25N 60W. IN  
THE MID-LEVELS...A RIDGE AXIS IS FORECAST TO ARRIVE FROM THE WEST  
ON WEDNESDAY. THESE CHANGES IN THE UPPER PATTERN WILL BECOME LESS  
FAVORABLE FOR HEAVY RAINFALL ON WEDNESDAY...YET THE MOIST PLUME IS  
FORECAST TO CONTINUE LINGERING ACROSS THE VI AND EASTERN PUERTO  
RICO...TO STILL FAVOR MODERATE AFTERNOON CONVECTION. A DRYING  
TREND FOLLOWS...AIDED BY A PERSISTENT MID-LEVEL RIDGE PATTERN AND  
BY THE ABSENCE OF SIGNIFICANT UPPER TROUGHS OVER THE REGION. LOWER  
SURFACE PRESSURES TO THE NORTH...IN RESPONSE TO THE EFFECTS OF THE  
LARGE UPPER TROUGH CURRENTLY IN THE BAHAMAS...WILL CONTINUE TO  
FAVOR SOUTHEASTERLY TRADE WIND DIRECTIONS THROUGH FRIDAY. ON  
SATURDAY...THE TRADES ARE FORECAST TO BECOME EASTERLIES ONCE AGAIN.  
 
IN TERMS OF PRECIPITATION...EXPECT WET CONDITIONS TO CONTINUE ON  
TUESDAY...WHEN EXPECT SCATTERED MAXIMA OF 0.5-1 INCH IN  
SOUTHEAST...EASTERN AND CENTRAL PUERTO RICO. IN THE NORTHWEST AND  
NORTH-CENTRAL PUERTO RICO...AFTERNOON CONVECTION WILL FAVOR MAXIMA  
OF 1-2 INCHES. WET CONDITIONS ARE ALSO EXPECTED IN THE VI...WHERE  
EXPECT MAXIMA OF 0.25-0.5 INCHES...AND HIGHER AMOUNTS IN VIEQUES.  
ON WEDNESDAY...EXPECT SCATTERED AMOUNTS OF 0.2-0.3 INCHES IN THE  
VI AND SOUTHERN/EASTERN PUERTO RICO. UNDER SOUTHEASTERLY  
TRADES...AFTERNOON CONVECTION WILL LIKELY CLUSTER IN NORTHWEST AND  
NORTH-CENTRAL PUERTO RICO...WHERE EXPECT MAXIMA OF 1-1.75 INCHES.  
ON THURSDAY...EXPECT A NOTICEABLE RETURN TO DRIER CONDITIONS.  
AFTERNOON MAXIMA IN NORTHWEST PUERTO RICO WILL FAVOR AMOUNTS OF  
1-1.25 INCHES. FRIDAY WILL LIKELY BE THE DRIEST DAY WHEN MAXIMA OF  
0.5-0.75 INCHES IS EXPECTED IN NORTHWEST PUERTO RICO. ON  
SATURDAY...UNDER EASTERLY TRADES...EXPECT MAXIMA TO RELOCATED TO  
THE CENTRAL AND WESTERN AND SOUTHWESTERN CORDILLERA...WHERE EXPECT  
MAXIMA OF 1-1.25 INCHES.  
 
GALVEZ/ACOSTA...WPC (USA)  

 
 
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