642  
FXCA20 KWBC 031058  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
657 AM EDT FRI NOV 03 2017  
 
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM NOV 03/06  
UTC: UNDER INFLUENCE OF A BUILDING MID/UPPER LEVEL RIDGE OVER  
MEXICO...A LONG WAVE TROUGH IS TO AMPLIFY ACROSS THE FLORIDA  
PENINSULA/THE BAHAMAS-CUBA TO THE WESTERN CARIBBEAN ON SATURDAY.  
THIS IS TO THEN DRIFT TO THE EAST-SOUTHEAST...MOVING TO THE  
SOUTHEAST BAHAMAS/TURKS-EASTERN CUBA-JAMAICA-CENTRAL CARIBBEAN  
LATER ON SUNDAY/MONDAY MORNING. AS THE TROUGH DEEPENS...A RIDGE  
OVER THE EASTERN CARIBBEAN IS TO COLLAPSE. AS A RESULT...THE  
STRONG TRADE WINDS CAP ENVELOPING THE FORECAST AREA IS TO  
GRADUALLY EASE ITS FOOTHOLD DURING THE LATE MORNING HOURS ON  
SATURDAY. ENVIRONMENTAL CONDITIONS ARE TO THEN REMAIN FAVORABLE  
FOR DEEP CONVECTION TO DEVELOP THROUGH THE MIDDLE OF NEXT WEEK.  
THIS IS TO COINCIDE WITH ARRIVAL OF AN ATMOSPHERIC KELVIN WAVE  
EARLY NEXT WEEK AS INDICATED BY TH CFS CLIMO MODEL GUIDANCE. THIS  
WILL LEAD TO AN ENHANCED POTENTIAL FOR HEAVY RAINFALL AMOUNTS.  
 
FURTHERMORE...A WANING TUTT TO THE EAST SUSTAINS AN INDUCED TROUGH  
IN THE EASTERLY TRADES. AS THE UPPER LEVEL RIDGE OVER THE BASIN  
CRUMBLES THE TUTT ALOFT IS GOING TO WEAKEN AND LIFT AWAY. THE LOW  
LEVEL PERTURBATION WILL THEN DETACH FROM THE UPPER LEVEL  
FEATURE...MOVING ACROSS THE EASTERN CARIBBEAN TO SOUTHERN  
HISPANIOLA DURING THE WEEKEND. UNDER INFLUENCE OF THIS FEATURE A  
LONG FETCH SOUTHEASTERLY FLOW WILL ESTABLISH ACROSS THE ISLAND  
CHAIN/EASTERN CARIBBEAN. PWAT CONTENT ACROSS PUERTO RICO AND THE  
VIRGIN ISLES INCREASES TO 1.75 INCHES ON SATURDAY AND AROUND TWO  
INCHES ON MONDAY. IN RESPONSE TO THESE CHANGES THE GFS AND UKMET  
AGREE ON PATTERN RAPIDLY GROWING UNSETTLED DURING THE WEEKEND...TO  
INITIALLY FAVOR MODERATE RAINFALL AMOUNTS INCREASING TO HEAVY  
EARLY NEXT WEEK. THE ECMWF...IN CONTRAST...SEEMS TO BE DOWNPLAYING  
THE POTENTIAL FOR HEAVY RAINFALL AMOUNTS. CONSIDERING THAT THE  
MODELS GENERALLY AGREE ON DEEP PLUME OF TROPICAL MOISTURE TO  
ENVELOP THE FORECAST AREA DURING THE WEEKEND/EARLY NEXT WEEK...WE  
ARE LEANING TOWARDS THE WETTER SOLUTION.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  
 

 
 
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