227  
FXCA20 KWBC 311831  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
230 PM EDT TUE OCT 31 2017  
 
TROPICAL DISCUSSION FROM OCT 31/12 UTC: BROAD CELL OF THE  
SUBTROPICAL RIDGE HAS BECOME THE DOMINANT FEATURE ACROSS THE  
WESTERN ATLANTIC-CARIBBEAN BASIN TO NORTHERN SOUTH AMERICA/CENTRAL  
AMERICA. AT 500/250 HPA THE UPPER RIDGE ANCHORS ON A CLOSED HIGH  
NORTH OF HAITI. AS THE RIDGE HOLDS...POLAR TROUGHS ARE TO RAPIDLY  
LIFT OVER THIS AXIS...WITH ONE PULLING ACROSS THE NORTH ATLANTIC  
EARLY IN THE CYCLE. AT LOW LEVELS THIS SUSTAINS A MEANDERING FRONT  
OVER THE TURKS-SOUTHEAST BAHAMAS-EASTERN CUBA TO THE WESTERN  
CARIBBEAN/YUCATAN PENINSULA. THROUGH WEDNESDAY EVENING THE FRONT  
RETROGRESSES TO THE CENTRAL BAHAMAS-CENTRAL CUBA WHILE TRAILING TO  
THE NORTHWEST CARIBBEAN/YUCATAN PENINSULA. AS IT LOSES ITS UPPER  
LEVEL SUPPORT... BOUNDARY IS TO THEN FRONTOLIZE LATER ON  
THURSDAY/FRIDAY MORNING. MEANWHILE...AS IT MEANDERS ACROSS THE  
TURKS/SOUTHEAST BAHAMAS-EASTERN CUBA THIS IS TO FAVOR RAINFALL  
AMOUNTS OF 05-10MM/DAY AND ISOLATED MAXIMA OF 15MM. AS IT  
RETROGRESSES ACROSS THE CAYMAN ISLES ON WEDNESDAY MORNING IT IS TO  
SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF  
15-25MM...WHILE OVER CENTRAL CUBA/CENTRAL BAHAMAS EXPECTING  
RAINFALL WIDELY ISOLATED CONVECTION WITH LIGHT RAINFALL AMOUNTS.  
THIS IS TO ALSO FAVOR PREFRONTAL CONVECTION ACROSS NORTHEAST  
HONDURAS-NICARAGUA...TO TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY  
AND MAXIMA OF 20-35MM. ON WEDNESDAY IT DECREASES TO 05-10MM/DAY  
AND MAXIMA OF 15-25MM. PREFRONTAL CONVECTION IS TO ALSO CLUSTER  
ACROSS JAMAICA...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-25MM. AS THE FRONT RETROGRESSES TO  
THE WESTERN CARIBBEAN...MOIST PLUME IS TO ENVELOP BELIZE-NORTHERN  
GUATEMALA...WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF  
15MM ON WEDNESDAY...WHILE ON THURSDAY EXPECT ACCUMULATION OF  
10-15MM/DAY AND MAXIMA OF 20-40MM.  
 
MEANWHILE...BROAD MID/UPPER LEVEL RIDGE IS TO PERSIST ACROSS THE  
CARIBBEAN/WESTERN ATLANTIC. POLAR FRONTS EXITING THE EASTERN USA  
WILL LIFT OVER THIS AXIS...LEADING TO GRADUAL EROSION OF MID/UPPER  
LEVEL RIDGE PATTERN LATER IN THE WEEK. SIMULTANEOUSLY...THE  
ASSOCIATED MID LEVEL HIGH MOVES FROM NORTHERN HAITI TO EASTERN  
CUBA ON WEDNESDAY...RELOCATING ACROSS THE YUCATAN TO THE CAMPECHE  
SOUND LATER ON THURSDAY. AS IT SETTLES OVER MEXICO LATER IN THE  
WEEK THIS WILL THEN FAVOR THE NORTHWARD AMPLIFICATION OF THE  
MID/UPPER LEVEL RIDGE ACROSS MEXICO TO THE WESTERN USA. OVER THE  
NORTHEAST CARIBBEAN THE MEANDERING UPPER LEVEL RIDGE WILL SUSTAIN  
A TRADE WINDS CAP LATER TODAY. THIS IS TO GENERALLY HOLD THROUGH  
THE END OF THE WEEK...INHIBITING ORGANIZED DEEP CONVECTION ACROSS  
THE NORTHEAST CARIBBEAN ISLES. AT LOW LEVELS...A BROAD RIDGE  
BUILDS ACROSS THE EASTERN USA EARLY IN THE CYCLE. THIS IS TO  
GRADUALLY BECOME DOMINANT FEATURE OVER THE WESTERN ATLANTIC/NORTH  
OF THE ISLANDS ON WEDNESDAY. IN RESPONSE TO THIS FEATURE THE  
LOW/MID LEVEL WINDS ARE TO GRADUALLY BACK TO THE NORTHEAST. THIS  
IS TO SUSTAIN A COOL ADVECTIVE PATTERN ACROSS THE NORTHEAST  
CARIBBEAN ON WEDNESDAY-THURSDAY. THIS WILL BE ACCOMPANIED BY A  
DECREASE IN DIURNAL CONVECTION. MEANWHILE...OVER PUERTO RICO AND  
EASTERN HISPANIOLA INITIALLY EXPECTING RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15MM. THIS IS TO GRADUALLY DECREASES TO  
00-05MM/DAY ON THURSDAY.  
 
FARTHER SOUTH...THE EASTERN PACIFIC ITCZ IS TO MEANDER OVER COSTA  
RICA-PANAMA TO NORTHERN COLOMBIA. AS IT MEANDERS ACROSS SOUTHERN  
CENTRAL AMERICA THIS IS TO FAVOR SCATTERED DEEP CONVECTION WITH  
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS  
COLOMBIA-NORTHWEST VENEZUELA EXPECTING SIMILAR RAINFALL  
AMOUNTS...WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM  
THROUGH FRIDAY MORNING. OVER CENTRAL-EASTERN VENEZUELA DIURNAL  
CONVECTION ALONG THE NEAR EQUATORIAL TROUGH WILL SUSTAIN RAINFALL  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. ON WEDNESDAY IT  
INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-35MM...WHILE ON THURSDAY  
THE MAXIMA PEAKS AT 15-25MM. OVER THE ATLANTIC...ITCZ REMAINS  
NORTH OF THE GUIANAS. AS A RESULT THE MOST ACTIVE CONVECTION IS  
EXPECTED ACROSS GUYANA...WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND  
MAXIMA OF 15MM.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
50W 53W 56W 58W 61W 63W 65W 67W TUTT INDCD 18N  
58W 59W 60W 61W 62W 64W 66W 69W TUTT INDCD 26N  
 
59W 60W 62W 64W 67W DISSIPATES TW 15N  
78W 79W 80W DISSIPATES TW 15N  
 
A DEEP TUTT TO THE EAST OF THE SUBTROPICAL RIDGE SUSTAINS AN  
INDUCED TROUGH IN THE EASTERLY TRADES...WITH AXIS ALONG 50W. THIS  
MEANDERS WEST INTO NORTHERN FRENCH GUIANA LATER TODAY/EARLY  
WEDNESDAY MORNING...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF  
00-05MM/DAY IN ISOLATED AND MAXIMA OF 10MM. AXIS IS NOW EXPECTED  
TO MEANDER WEST TO THE ISLAND CHAIN EARLY ON THURSDAY MORNING.  
OVER TRINIDAD/GRENADINES TO NORTHEAST VENEZUELA IT IS TO FAVOR  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM AS IT INTERACTS  
WITH THE ITCZ.  
 
THE TUTT ALOFT ALSO SUSTAINS A SECONDARY PERTURBATION WITH AXIS  
ALONG 58W AND TO THE NORTH OF 20N. AS IT RETROGRESSES OVER THE  
NORTHEAST CARIBBEAN ISLES LATER ON WEDNESDAY/THURSDAY MORNING THIS  
WAVE WILL NOT BE ABLE TO OVERCOME NEGATIVE INFLUENCE OF MID LEVEL  
RIDGE PATTERN. AS A RESULT...ONLY EXPECTING LIGHT CONVECTION AS IT  
ENTERS THE NORTHEAST CARIBBEAN WITH ACCUMULATION OF 00-05MM/DAY  
AND MAXIMA OF 10MM.  
 
A TROPICAL WAVE ALONG 59W AND SOUTH OF 15N IS TO SUSTAIN SCATTERED  
CONVECTION ACROSS TRINIDAD AND TOBAGO AND NORTHEAST VENEZUELA  
EARLY IN THE CYCLE...WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA  
OF 15MM. OVER CENTRAL VENEZUELA THIS IS TO THEN TRIGGER RAINFALL  
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM ON WEDNESDAY.  
 
AN ILL DEFINED WAVE ALONG 79W TO 15N IS FORECAST TO DISSIPATE  
EARLY ON WEDNESDAY MORNING. MEANWHILE...ACROSS EASTERN PANAMA  
EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
DAVISON...WPC (USA)  
 

 
 
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