876  
FXCA20 KWBC 081138  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
638 AM EST MON JAN 08 2018  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JAN 08/06  
UTC: FORECAST AREA LIES ON THE CONVERGENT SIDE OF A MID/UPPER  
LEVEL RIDGE DOMINATING THE EASTERN CARIBBEAN ISLES. EAST OF THIS  
AXIS...A TUTT LOW NEAR 16N 48W ANCHORS A SHORT WAVE TROUGH OVER  
THE TROPICAL ATLANTIC. THIS FAVORS GENERATION OF SHALLOW CLOUD  
CLUSTERS THAT FROM TIME-TO-TIME STREAM ACROSS THE EASTERN  
CARIBBEAN...TRIGGERING LIGHT CONVECTION IN PASSING RAIN SHOWERS.  
 
PERSISTENT MID/UPPER LEVEL RIDGE IS TO DOMINATE THE FLOW ACROSS  
THE EASTERN CARIBBEAN/CENTRAL ATLANTIC...MEANWHILE BLOCKING A  
SHORT WAVE TROUGH ON THE SOUTHERN STREAM THAT IS FORECAST TO  
STREAM ACROSS THE GULF OF MEXICO TO CUBA/NORTHWEST CARIBBEAN BY  
MIDWEEK. AS THE RIDGE REMAINS WELL ENTRENCHED ACROSS THE FORECAST  
AREA...THE ASSOCIATED TRADE WINDS CAP IS EXPECTED TO HOLD THROUGH  
THE END OF THE WEEK...TO CONTINUE INHIBITING ORGANIZED DEEP  
CONVECTION. LIKEWISE...THE TUTT TO THE EAST OF THE ISLANDS IS TO  
GENERALLY HOLD DURING THE NEXT FOUR-TO-FIVE DAYS...TO CONTINUE  
FAVORING GENERATION OF SHALLOW CLOUD CLUSTERS AND THE OCCASIONAL  
INDUCED TROUGH IN THE EASTERLY TRADES. AT LOW LEVELS...UNDER THE  
INFLUENCE OF BUILDING CELL OF THE BERMUDA RIDGE TO THE NORTH OF  
THE ISLANDS...BRISK EASTERLY TRADES ARE EXPECTED DURING THE NEXT  
FEW DAYS...WITH THE 925/950 HPA WINDS TO PEAK AROUND 30KT ON  
WEDNESDAY-FRIDAY.  
 
AS THE WINDS SURGE...GLOBAL MODELS AGREE ON PWAT CONTENT TO  
INCREASE TO AROUND 1.50-1.75 INCHES ON WEDNESDAY-FRIDAY. THIS WILL  
BE ACCOMPANIED BY AN INCREASED IN CONVECTION...WITH GLOBAL MODEL  
GUIDANCE SHOWING MOST ACTIVE AFFECTING THE VIRGIN ISLES/EASTERN  
PUERTO RICO-SAN JUAN METRO AREA. THE STRONG EASTERLY TRADES WILL  
GENERALLY LIMIT THEIR TIME ON STATION. AS A RESULT...EXPECTING  
HEAVIEST AMOUNTS TO LIMIT TO NORTHEAST PUERTO RICO.  
 
DAVISON...WPC (USA)  
 

 
 
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