090  
FXCA20 KWBC 121913  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
312 PM EDT THU OCT 12 2017  
 
TROPICAL DISCUSSION FROM OCT 12/12 UTC: A WEAKENING NORTHERLY  
SURGE IN THE GULF OF MEXICO IS ENHANCING MOISTURE CONVERGENCE  
ALONG THE COASTS OF VERACRUZ IN MEXICO. THIS WILL CONTINUE  
SUSTAINING LOCALLY HEAVY RAINFALL THROUGH SATURDAY. THOUGH EARLY  
FRIDAY...EXPECTING 20-40MM/DAY AND MAXIMA OF 50-100MM. BY  
FRIDAY-SATURDAY...THIS DECREASES TO 10-15MM/DAY AND MAXIMA OF  
20-35MM. AMOUNTS WILL DECREASE RAPIDLY AFTER. ALSO IN  
MEXICO...DIURNAL CONVECTION ALONG THE SIERRA MADRE OCCIDENTAL AND  
SIERRA MADRE DEL SUR WILL LEAD LIGHT RAINFALL ACCUMULATIONS ON A  
DAILY BASIS. EXPECTING 05-10MM/DAY AND MAXIMA OF 15-20MM ON  
THURSDAY. THIS IS DECREASING TO 00-05MM/DAY AND MAXIMA OF 10MM IN  
THE SIERRA MADRE OCCIDENTAL FROM FRIDAY THROUGH SUNDAY...AND  
05-10MM/DAY AND MAXIMA OF 15MM IN THE SIERRA MADRE DEL SUR DURING  
THE SAME PERIOD.  
 
ANOTHER REGION OF INTEREST IS THE CUBA AND THE BAHAMAS...WHERE A  
STRONG UPPER LOW IS FORECAST TO MEANDER THROUGH THE CYCLE. THIS  
WILL CONTINUE SUSTAINING ENHANCED CONVECTIVE INSTABILITY AND  
NUMEROUS SHOWERS AND THUNDERSTORMS IN THE REGION THROUGH SUNDAY.  
LARGEST ACCUMULATIONS THROUGH EARLY SATURDAY...LARGEST  
ACCUMULATIONS ARE TO CLUSTER IN WESTERN CUBA...WHERE EXPECTING  
10-15MM/DAY AND MAXIMA OF 20-35MM. IN THE NORTHERN BAHAMAS  
EXPECTING 05-10MM/DAY AND MAXIMA OF 15-25MM THROUGH THE CYCLE.  
 
ACROSS THE CENTRAL CARIBBEAN...ACTIVITY WILL BE MODULATED BY A  
TROPICAL WAVE (SEE BELOW). AT MID-UPPER LEVELS...A MID-LEVEL RIDGE  
IS SETTING IN PLACE. THIS...COMBINED WITH THE INFLUENCE OF THE  
CONVERGENT PHASE OF THE MADDEN JULIAN OSCILLATION THAT IS FORECAST  
TO EXTEND OVER THE REGION THROUGH THE NEXT 5-10 DAYS...WILL LIMIT  
RAINFALL ACCUMULATIONS. IN JAMAICA...EXPECTING MAXIMA OF 15MM ON  
THURSDAY AS THE WAVE CROSSES. ON FRIDAY...UNDER THE INFLUENCE OF  
THE TRAILING MOISTURE PLUME...EXPECTING RAINFALL TOTALS OF  
05-10MM/DAY AND MAXIMA OF 15-20MM. IN HISPANIOLA...THE ARRIVAL OF  
A MOISTURE POOL FROM THE NORTHEAST WILL LEAD TO A PEAK IN  
ACCUMULATIONS ON FRIDAY-EARLY SATURDAY...WHEN EXPECTING  
05-10MM/DAY AND MAXIMA OF 15-25MM. TO THE EAST...IN PUERTO RICO  
AND THE LEEWARD ISLANDS...EXPECTING LIGHT RAINFALL ACCUMULATIONS  
THROUGH THE CYCLE...WITH MAXIMA GENERALLY UNDER 10MM...WITH THE  
EXCEPTION OF ISOLATED THUNDERSTORMS.  
 
IN NORTHERN SOUTH AMERICA...ACTIVITY WILL ORGANIZE WITH THE NET  
AND TROPICAL WAVES. ON THURSDAY-EARLY FRIDAY EXPECTING AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-35MM FROM GUYANA WEST INTO SOUTHERN  
VENEZUELA. AS THE WAVE ENTERS THE CONTINENT ON  
FRIDAY-SATURDAY...EXPECTING AN INCREASE IN AMOUNTS IN TRINIDAD AND  
TOBAGO TO 05-10MM/DAY AND MAXIMA OF 15MM.HOWEVER...MOISTURE PLUME  
OF 55+MM OF PRECIPITABLE WATER WILL ARRIVE ON SATURDAY THROUGH  
SUNDAY. THIS WILL LEAD TO AN INCREASE IN ACCUMULATIONS TO  
10-15MM/DAY AND MAXIMA OF 20-40MM...INCLUDING THE OCCURRENCE OF  
STREAMERS. ALSO ON SATURDAY-SUNDAY...CONVECTION IN ASSOCIATION  
WITH THE WAVE WILL LEAD TO 10-15MM/DAY AND MAXIMA OF 20-30MM IN  
WESTERN VENEZUELA AND EASTERN COLOMBIA.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
52W 55W 58W 61W 64W 67W 70W 73W TW 20N  
76W 79W 81W 84W 86W 88W 90W 91W TW 20N  
 
A TROPICAL WAVE INITIALIZED AT 52W ARRIVES IN THE BASIN DURING  
LATE THURSDAY-FRIDAY...TO ENHANCE CONVECTION IN WESTERN SURINAME  
AND GUYANA...PRODUCING MAXIMA OF 20-30MM/DAY. ON  
FRIDAY-SATURDAY...EXPECTING SIMILAR AMOUNTS IN GUYANA AND  
NORTHEASTERN VENEZUELA. SIMILAR AMOUNTS ARE EXPECTED ON  
SATURDAY-SUNDAY ACROSS WESTERN VENEZUELA/EASTERN COLOMBIA.  
 
A TROPICAL WAVE...INITIALIZED AT 76W IS STILL ILL-DEFINED...BUT  
PROPAGATING ACROSS JAMAICA. THROUGH FRIDAY...THE WAVE WILL LEAD TO  
MAXIMA OF 15-20MM/DAY IN PANAMA AND MAXIMA OF 15MM IN JAMAICA.  
TRAILING MOISTURE PLUME BEHIND THE WAVE WILL ENHANCE ACCUMULATIONS  
IN JAMAICA ON FRIDAY...TO PRODUCE 05-10MM/DAY AND MAXIMA OF  
15-20MM. AS IT CROSSES PANAMA AND COSTA RICA ON FRIDAY...EXPECTING  
05-10MM/DAY AND MAXIMA OF 15-20MM.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
GALVEZ...WPC (USA)  

 
 
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