976  
FXCA20 KWBC 241843  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
243 PM EDT TUE OCT 24 2017  
 
TROPICAL DISCUSSION FROM OCT 24/12 UTC: A DEEP/HIGH AMPLITUDE  
TROUGH DOMINATES THE FLOW ACROSS THE CENTRAL/EASTERN USA TO THE  
GULF OF MEXICO. THE TROUGH REACHES MAXIMUM AMPLITUDE EARLY IN THE  
CYCLE. ON WEDNESDAY...AS A RIDGE BUILDS TO THE WEST...THE TROUGH  
WILL MOVE OFF THE EASTERN USA TO THE WESTERN ATLANTIC WHILE  
TRAILING TO THE NORTHWEST BAHAMAS-WESTERN CUBA. AXIS IS TO THEN  
RAPIDLY PULL OVER A RIDGE TO THE EAST. AT LOW LEVELS THIS IS TO  
SUSTAIN A PROGRESSIVE FRONT ACROSS CENTRAL FLORIDA-NORTHERN  
YUCATAN/SOUTHERN STATES OF MEXICO LATER TODAY. SIMULTANEOUSLY...A  
BUILDING POLAR RIDGE TO THE WEST SUSTAINS A NORTHERLY WIND SURGE  
OF 20-30KT ACROSS THE WESTERN GULF TO THE SOUTHERN STATES OF  
MEXICO. THIS...IN-TURN...FAVORS A TEHUANTEPECER JET OF 45-50KT.  
THE STRONG BOUNDARY LAYER WINDS ARE TO PERSIST THROUGH THURSDAY  
MORNING. UNDER INFLUENCE OF THE STRONG NORTHERLIES THE FRONT MOVES  
TO SOUTH FLORIDA-WESTERN CUBA-THE YUCATAN/SOUTHERN MEXICO EARLY ON  
WEDNESDAY. LATER ON WEDNESDAY IT CONTINUES TO THE NORTHWEST  
BAHAMAS WHILE TRAILING ACROSS WESTERN CUBA TO THE GULF OF  
HONDURAS. EARLY ON THURSDAY MORNING THE FRONT IS TO MOVE TO THE  
CENTRAL BAHAMAS-CENTRAL CUBA WHILE TRAILING TO THE WESTERN  
CARIBBEAN/GULF OF HONDURAS...WHERE IT IS TO REMAIN THROUGH FRIDAY  
MORNING. THE PROGRESSIVE FRONT SUSTAINS A PREFRONTAL SHEAR LINE  
ACROSS WESTERN CUBA TO BELIZE/GULF OF HONDURAS. THIS MEANDERS EAST  
ALONG THE COAST OF HONDURAS EARLY ON WEDNESDAY...MOVING TO THE  
CAYMAN ISLES-NORTHEAST HONDURAS/NICARAGUA LATER ON WEDNESDAY.  
BOUNDARY IS TO THEN BECOME ILL DEFINED AS THE FRONT STALLS OVER  
THE NORTHWEST CARIBBEAN.  
 
THE FRONT AND STRONG FRONTAL NORTHERLIES WILL COMBINE WITH  
ANOMALOUSLY WARM SEA SURFACE TEMPERATURES ACROSS THE GULF OF  
MEXICO-WESTERN CARIBBEAN TO SUSTAIN HEAVY RAINFALL AMOUNTS.  
ACROSS SOUTHERN VERACRUZ-CHIAPAS IN SOUTHERN MEXICO AND CENTRAL  
GUATEMALA AND BELIZE EXPECTING RAINFALL AMOUNTS OF 25-50MM/DAY AND  
MAXIMA OF 75-125MM. OVER THE YUCATAN PENINSULA FRONTAL CONVECTION  
WILL RESULT IN RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF  
30-60MM. OVER NORTHERN HONDURAS/CENTRAL GUATEMALA THE SHEAR LINE  
WILL SUSTAIN RAINFALL AMOUNTS OF 50-100MM/DAY AND MAXIMA OF  
150-250MM/DAY THROUGH THURSDAY. ON THURSDAY TO FRIDAY IT DECREASES  
TO 25-50MM/DAY AND MAXIMA OF 75-125MM. OVER THE NORTHWEST BAHAMAS  
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM ON  
WEDNESDAY TO THURSDAY...WHILE ACROSS WESTERN-CENTRAL CUBA  
EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.  
 
THE DEEPENING POLAR TROUGH OVER THE EASTERN USA/GULF OF MEXICO IS  
TO INTERACT WITH A LOW/TROUGH OVER THE SOUTHERN CARIBBEAN. THE  
MODELS NOW DIVERGE ON HOW THIS FEATURE IS GOING TO EVOLVE...WITH  
BOTH EUROPEAN MODELS SHOWING THE LOW LIFTING ALONG THE COAST OF  
NICARAGUA TO THE WESTERN CARIBBEAN...WHILE THE GFS NOW FORECASTS  
THE LOW TO MEANDER WEST ACROSS COSTA RICA/SOUTHERN NICARAGUA ALONG  
THE ITCZ TO THE EASTERN TROPICAL PACIFIC. ALTHOUGH BOTH SOLUTIONS  
ARE POSSIBLE...THE LATEST SATELLITE IMAGERY IS GIVING SUPPORT TO  
THE GFS SOLUTION. MEANWHILE...EXPECTING HEAVY CONVECTION TO AFFECT  
WESTERN PANAMA-COSTA RICA/SOUTHERN NICARAGUA WITH ACCUMULATION OF  
25-50MM/DAY AND MAXIMA OF 75-125MM. THROUGH THURSDAY IT DECREASES  
TO 15-20MM/DAY AND MAXIMA OF 35-70MM. THE EVOLVING PATTERN IS TO  
ALSO SUSTAIN A PLUME OF DEEP TROPICAL MOISTURE ACROSS THE CENTRAL  
CARIBBEAN...TO REACH JAMAICA AND THE CAYMAN ISLES LATER ON  
WEDNESDAY/EARLY THURSDAY. THE MOIST INFLOW WILL FEED CONVECTIVE  
DEVELOPMENT TO RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND  
MAXIMA OF 20-40MM. ACROSS COLOMBIA TO NORTHWEST VENEZUELA  
EXPECTING DIURNAL CONVECTION TO FAVOR RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-30MM.  
 
EAST OVER THE CARIBBEAN...A TUTT EXTENDS SOUTH FROM A LOW NORTH OF  
PUERTO RICO TO THE EASTERN CARIBBEAN/EASTERN VENEZUELA. THE LOW  
NORTH OF THE ISLANDS WEAKENS TO AN OPEN TROUGH EARLY IN THE  
PERIOD...WHILE SIMULTANEOUSLY A NEW LOW CLOSES OVER THE  
SOUTHEASTERN CARIBBEAN EARLY ON WEDNESDAY. THIS PATTERN IS TO THEN  
HOLD THROUGH THE END OF THE WEEK. PUERTO RICO/HISPANIOLA AND THE  
VIRGIN ISLES LIE ON THE CONVERGENT SIDE OF THE UPPER LEVEL  
TROUGH...WHILE THE FRENCH-WINDWARD ISLES AND EASTERN  
VENEZUELA/GUYANA REMAIN ON THE DIVERGENT SIDE. THIS IS ENHANCING  
ITCZ RELATED CONVERGENCE ACROSS TRINIDAD-GRENADINES AND DIURNAL  
CONVECTION ACROSS EASTERN VENEZUELA-GUYANA...WHERE WE EXPECT  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM...WITH DAILY  
MAXIMA DECREASING 20-30MM LATER ON THURSDAY.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
50W 53W 55W 58W 60W 62W 64W 67W TW 12N  
55W 57W 59W 60W 62W 63W 64W 66W TUTT-IND 17N  
61W 63W 66W 68W 70W 72W 74W 76W TW 13N  
62W 65W 67W DISSIPATES TUTT-IND 26N  
 
TROPICAL WAVE ALONG 50W AND SOUTH OF 12N PULLS ACROSS NORTHERN  
FRENCH GUIANA/SURINAME EARLY IN THE PERIOD...TO SUSTAIN RAINFALL  
AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. ACROSS SURINAME-GUYANA  
THIS IS TO THEN TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA  
OF 20-35MM ON WEDNESDAY. OVER EASTERN/CENTRAL VENEZUELA EXPECTING  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM ON THURSDAY.  
 
THE DEEPENING TUTT OVER THE EASTERN CARIBBEAN IS TO INDUCED AN  
INVERTED TROUGH IN THE EASTERLY TRADES ALONG 55W EARLY IN THE  
PERIOD. THE INDUCED PERTURBATION MOVES TO THE FRENCH/LEEWARD ISLES  
LATER ON WEDNESDAY MORNING...TO SUSTAIN RAINFALL AMOUNTS OF  
00-05MM/DAY AND MAXIMA OF 10MM. IT THEN MEANDERS ACROSS THE  
NORTHEAST CARIBBEAN THROUGH THURSDAY MORNING...MEANWHILE FAVORING  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THE WAVE  
REACHES THE VIRGIN ISLES AND PUERTO RICO ON FRIDAY TO SUSTAIN  
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM.  
 
TROPICAL WAVE ALONG 61W AND SOUTH OF 13N IS TO TRIGGER SCATTERED  
CONVECTION ACROSS EASTERN-CENTRAL VENEZUELA WITH ACCUMULATION OF  
10-15MM/DAY AND MAXIMA OF 20-40MM. OVER THE ABC ISLANDS EXPECTING  
ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM ON WEDNESDAY. THIS  
REACHES WESTERN VENEZUELA/EASTERN COLOMBIA EARLY ON THURSDAY  
MORNING...TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF  
20-30MM.  
 
ANOTHER TUTT INDUCED PERTURBATION EXTENDS ALONG 62W. THIS MOVES TO  
THE CONVERGENT SIDE OF THE UPPER LEVEL TROUGH LATER TODAY...WITH  
PERTURBATION TO RAPIDLY WEAKEN ON WEDNESDAY MORNING WHILE SHEARING  
TO THE NORTH-NORTHWEST. MEANWHILE...EXPECT RAINFALL AMOUNTS OF  
00-05MM/DAY AND MAXIMA OF 10MM.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
DAVISON...WPC (USA)  

 
 
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