892  
FXCA20 KWBC 191126  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
725 AM EDT THU OCT 19 2017  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE VI FROM OCT 19/06  
UTC: DRY WEATHER PATTERN IS ESTABLISHING IN THE ISLANDS AND IS  
FORECAST TO LAST AT LEAST INTO EARLY NEXT WEEK. A TRADE WIND SURGE  
HAS CROSSED THE ISLANDS FROM EAST TO WEST...AND NOW EXTENDS ACROSS  
LA MONA PASSAGE BETWEEN PUERTO RICO AND THE DOMINICAN REPUBLIC.  
THE SURGE IS ACCOMPANIED BY STRONG TRADE WIND SPEEDS...WHICH ARE  
REACHING 20-30KT BETWEEN 925 AND 700 HPA. FURTHERMORE...THE SURGE  
IS ACCOMPANIED BY A TRADE WIND CAP THAT SITS AT 900 HPA...BUT MORE  
THAN THE INVERSION ITSELF...THE FACTORS LIMITING CONVECTIVE  
DEVELOPMENT ARE (1) THE PRESENCE OF DRY AIR IN THE 900-600 HPA  
LAYER...AND (2) THE LOW-LEVEL WIND SHEAR ASSOCIATED WITH THE FAST  
TRADES. AT UPPER LEVELS...A LARGE TROUGH SITS OVER THE TROPICAL  
NORTH ATLANTIC...WHILE A RIDGE CENTERS TO THE NORTH OF PUERTO RICO  
AT 22N 65W. UPPER CONVERGENCE ASSOCIATED WITH THE UPPER  
TROUGH...WHICH IS FORECAST TO MEANDER WESTWARD...WILL HELP TO  
SUSTAIN THE SUBSIDENCE CAP DURING THE NEXT SEVERAL DAYS.  
 
ACCORDINGLY...EXPECTING LIGHT RAINFALL ACCUMULATIONS AT LEAST INTO  
EARLY NEXT WEEK. ACTIVITY WILL BE CHARACTERIZED BY BREEZY  
CONDITIONS AND VERY ISOLATED AND RAPIDLY-MOVING LIGHT TRADE WIND  
SHOWERS. LARGEST ACCUMULATIONS ARE EXPECTED IN EASTERN PUERTO RICO  
WHERE TRADE WIND INTERACTION WITH OROGRAPHIC FEATURES WILL SUSTAIN  
MAXIMA OF 0.25 INCHES/DAY. IN THE VIRGIN ISLANDS...PASSING SHOWERS  
WILL LEAD TO ACCUMULATIONS OF ABOUT 0.1 INCHES/DAY.  
OTHERWISE...EXPECTING TRACE RAINFALL AMOUNTS.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
GALVEZ...WPC (USA)  

 
 
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