133  
FXCA20 KWBC 161133  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
633 AM EST TUE JAN 16 2018  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN 16/06  
UTC: CELL OF THE SUBEQUATORIAL RIDGE DOMINATES THE UPPER LEVELS  
ACROSS THE CARIBBEAN BASIN/NORTHERN SOUTH AMERICA. AT 500 HPA...A  
HIGH OVER HISPANIOLA ANCHORS A SHORT WAVE RIDGE ACROSS THE  
NORTHEAST CARIBBEAN ISLES...WHERE IT FAVORS AN ELEVATED TRADE  
WINDS CAP. AT LOW LEVELS...TRADE WIND EASTERLIES PREVAIL...WITH  
CLOUD PATCHES STREAMING ACROSS THE NORTHEAST CARIBBEAN ISLES FROM  
TIME-TO-TIME.  
 
THE MID/UPPER LEVEL PATTERN IS TO HOLD NEARLY UNCHANGED THROUGH  
THE END OF THE WEEK...WITH ELEVATED TRADE WINDS CAP EXPECTED TO  
PERSIST THROUGH SATURDAY. AT LOW LEVELS...TRADE WIND EASTERLIES  
REGIME WILL REMAIN THE DOMINANT PATTERN...WITH GLOBAL MODELS  
AGREEING ON THE 850 HPA WINDS TO PEAK AT 10-15KT DURING THE NEXT  
FIVE DAYS. LATER DURING THE WEEKEND...SLIGHTLY STRONGER WINDS ARE  
EXPECTED TO PEAK AROUND 20KT. THE STRONGER WINDS WILL LIKELY FAVOR  
GENERATION OF STREAMERS ACROSS THE LEEWARD/VIRGIN ISLES.  
ALSO...EMBEDDED IN THE EASTERLY TRADES...CLOUD CLUSTERS ARE  
EXPECTED TO CONTINUE STREAMING ACROSS THE FORECAST AREA FROM  
TIME-TO-TIME. THESE WILL FEED CONVECTIVE DEVELOPMENT DURING THE  
NEXT FEW DAYS...WITH SOME REACHING PUERTO RICO DURING MAX HEATING  
TO FAVOR HEAVY RAINFALL AMOUNTS. MOST ACTIVE IS EXPECTED ACROSS  
WESTERN INTERIOR PORTIONS OF THE ISLAND/GUAJATACA BASIN... WITH  
LOCALIZED MAXIMA OF 2-4 INCHES HIGHLY PROBABLE. THE NAM SEEMS TO  
BE CAPTURING THIS QUITE WELL AND IT IS FAVORED OVER THE OTHER  
MODELS.  
 
DAVISON...WPC (USA)  
 

 
 
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