322  
FXCA20 KWBC 011830  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
229 PM EDT WED NOV 01 2017  
 
TROPICAL DISCUSSION FROM NOV 01/12 UTC: A 500/250 HPA HIGH OVER  
THE TURKS AND CAICOS/NORTHERN HAITI ANCHORS A BROAD RIDGE THAT  
EXTENDS FROM THE WESTERN ATLANTIC TO THE CARIBBEAN BASIN-NORTHERN  
SOUTH AMERICA TO CENTRAL AMERICA. POLAR PERTURBATIONS STREAMING  
ACROSS THE USA ARE TO PRESS AGAINST THIS RIDGE. DURING THE NEXT  
TWO DAYS THE RIDGE HOLDS ITS GROUND. BUT LATER ON FRIDAY...AS A  
TROUGH AMPLIFIES ACROSS THE BAHAMAS-CUBA...THE RIDGE OVER THE  
CARIBBEAN IS TO NEARLY COLLAPSE. HOWEVER...A SECONDARY CELL IS TO  
SIMULTANEOUSLY DEVELOP OVER MEXICO WHILE ANCHORING ON A CLOSED  
HIGH NEAR 20N 100W. THE LATTER IS TO THEN BUILD NORTH ACROSS  
MEXICO TO THE SOUTHWEST USA. THE BUILDING RIDGE WILL THEN SUSTAIN  
THE SOUTHWARD AMPLIFICATION OF THE TROUGH ACROSS CUBA TO THE  
WESTERN CARIBBEAN ON FRIDAY-SATURDAY. MEANWHILE...UNDER THE  
INFLUENCE OF THE MID LEVEL RIDGE...A STRONG CAP INVERSION  
ESTABLISHED ACROSS PUERTO RICO TO THE LESSER ANTILLES. ON THURSDAY  
THIS EXPANDS TO ENVELOP HAITI AND THE DOMINICAN REPUBLIC. THIS  
PATTERN IS TO HOLD DURING THE NEXT COUPLE OF DAYS...AND IT IS TO  
INHIBIT ORGANIZED DEEP CONVECTION. DOWNSTREAM FROM THE UPPER LEVEL  
RIDGE...A TUTT EXTENDS SOUTH FROM A LOW NEAR 28N 48W TO THE  
NORTHERN GUIANAS. AS THE RIDGE FLATTENS LATER IN THE WEEK THE TUTT  
IS TO ALSO WEAKEN.  
 
AT LOW LEVELS...BROAD RIDGE EXTENDS ACROSS THE WESTERN  
ATLANTIC/EASTERN USA TO THE GULF OF MEXICO/WESTERN CARIBBEAN.  
UNDER INFLUENCE OF THE TUTT TO THE EAST... AN INVERTED TROUGH NOW  
EXTENDS NORTH FROM THE GUIANAS TO A CLOSED LOW OVER THE CENTRAL  
ATLANTIC. A WANING BAROCLINIC BOUNDARY SEPARATES THESE  
SYSTEMS...AS IT EXTENDS ACROSS THE SOUTHEAST BAHAMAS-EASTERN  
CUBA-CAYMAN ISLES TO THE WESTERN CARIBBEAN. THE FRONT IS TO REMAIN  
NEARLY STATIONARY WHILE GRADUALLY WEAKENING TO AN INVERTED TROUGH  
ON FRIDAY. THE WANING FRONT WILL ENHANCE LOW LEVEL MOISTURE  
CONVERGENCE ACROSS THE CAYMAN ISLES TO FAVOR RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-25MM...WHILE OVER NORTHERN HONDURAS  
IT IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM  
THROUGH THURSDAY MORNING. ON THURSDAY PLUME OF MOISTURE IS TO THEN  
PROPAGATE ALONG THE COAST TO BELIZE-NORTHERN GUATEMALA...WHERE IT  
IS TO TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF  
20-40MM. ON FRIDAY IT DECREASES TO 10-15MM/DAY AND MAXIMA OF  
20-30MM. ACROSS JAMAICA INITIALLY EXPECTING RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-25MM... DECREASING TO 00-05MM/DAY AND  
MAXIMA OF 10MM ON THURSDAY-FRIDAY...WHILE ON FRIDAY TO SATURDAY  
EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM. OVER  
THE EASTERN CARIBBEAN...UNDER THE INFLUENCE OF THE RIDGE TO THE  
WEST AND THE INVERTED TROUGH TO THE EAST...A FRESH NORTHEASTERLY  
FLOW IS TO ESTABLISH EARLY IN THE CYCLE. THIS WILL SUSTAIN A COOL  
ADVECTIVE PATTERN THAT IS TO FAVOR GENERATION OF EARLY MORNING  
TRADE WIND SHOWERS ACROSS THE NORTHEAST CARIBBEAN ISLES. BUT FOR  
THE MOST PART THESE ARE TO ONLY TRIGGER LIGHT RAINFALL AMOUNTS.  
LATER ON FRIDAY...AS THE RIDGE WEAKENS...A PLUME OF TROPICAL  
MOISTURE LIFTS ACROSS THE WINDWARD ISLANDS TO SUSTAIN RAINFALL  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. ON SATURDAY THIS IS TO  
SPREAD ACROSS THE LEEWARD-VIRGIN ISLES TO SUSTAIN RAINFALL AMOUNTS  
OF 05-10MM/DAY AND MAXIMA OF 15-25MM IN DEEP CONVECTION.  
 
FARTHER SOUTH...THE EASTERN PACIFIC ITCZ MEANDERS ACROSS COSTA  
RICA-PANAMA TO NORTHERN COLOMBIA. OVER SOUTHERN CENTRAL AMERICA  
THIS IS TO FAVOR SCATTERED DEEP CONVECTION WITH ACCUMULATION OF  
05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS WESTERN  
COLOMBIA-NORTHWEST VENEZUELA EXPECTING SIMILAR RAINFALL  
AMOUNTS...WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM  
THROUGH FRIDAY MORNING. ON SATURDAY...AS A DEEP LAYER WESTERLY  
FLOW ESTABLISHES ACROSS THE EASTERN PACIFIC...THIS WILL INCREASES  
TO 10-15MM/DAY AND MAXIMA OF 20-40MM. OVER CENTRAL-EASTERN  
VENEZUELA DIURNAL CONVECTION ALONG THE NEAR EQUATORIAL TROUGH WILL  
SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ON  
THURSDAY-FRIDAY THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF  
15-25MM. THROUGH SATURDAY THE DAILY MAXIMA IS TO PEAK AT 15MM/DAY.  
OVER THE ATLANTIC...ITCZ REMAINS NORTH OF THE GUIANAS...WITH AXIS  
ALONG 08N/09N. OVER NORTHEAST VENEZUELA AND NORTHERN GUIANA THIS  
IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM.  
PLUME OF MOISTURE IS TO THEN LIFT ACROSS TRINIDAD TO THE SOUTHERN  
WINDWARD ISLES EARLY ON FRIDAY MORNING...TO TRIGGER RAINFALL  
AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. THROUGH THE DAY THIS  
INCREASES TO 05-10MM/DAY AND MAXIMA OF 15MM.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
56W 58W 61W 64W 66W 68W 70W 72W TUTT INDCD 21N  
60W 61W 63W 66W 69W 72W 74W 76W TUTT INDCD 27N  
 
61W 64W 67W 70W 72W 74W 76W 78W TW 11N  
80W DISSIPATES TW 12N  
 
A TUTT INDUCED TROUGH ALONG 56W TO 21N IS TO ENTER NORTHERN  
GUYANA-NORTHEAST VENEZUELA EARLY ON THURSDAY MORNING...TO TRIGER  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. OVER THE  
LESSER ANTILLES...IN A MID/UPPER LEVEL SUBSIDENT PATTERN... THIS  
IS TO ONLY FAVOR LIGHT RAINFALL AMOUNTS IN WIDELY ISOLATED  
CONVECTION. MOST ACTIVE IS EXPECTED OVER THE WINDWARD ISLES WHERE  
IT WILL RESULT IN RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF  
10MM. OVER EASTERN-CENTRAL VENEZUELA THIS IS TO THEN FAVOR  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM...WHILE OVER  
WESTERN VENEZUELA/EASTERN COLOMBIA IT IS TO TRIGGER RAINFALL  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.  
 
ANOTHER TUTT INDUCED WAVE ALONG 60W TO 27N WILL MEANDER WEST  
ACROSS THE NORTHEAST CARIBBEAN ISLES EARLY IN THE CYCLE.  
HOWEVER...THIS WILL NOT BE STRONG ENOUGH TO OVERCOME NEGATIVE  
INFLUENCE OF MID LEVEL RIDGE PATTERN. AS IT PULLS ACROSS THE  
NORTHERN LEEWARD/VIRGIN ISLES THIS IS TO TRIGGER RAINFALL AMOUNTS  
OF 00-05MM/DAY AND MAXIMA OF 10MM ON THURSDAY. THIS SPREADS ACROSS  
PUERTO RICO LATER ON THURSDAY TO FRIDAY...WHILE OVER THE DOMINICAN  
REPUBLIC EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF  
15-25MM.  
 
A TROPICAL WAVE ALONG 61W MOVES ACROSS EASTERN TO CENTRAL  
VENEZUELA EARLY ON THURSDAY...TO MEANWHILE FAVOR RAINFALL AMOUNTS  
OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ACROSS EASTERN COLOMBIA THIS  
DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-25MM ON THURSDAY. ACROSS  
NORTHERN TO WESTERN COLOMBIA IT IS TO THEN TRIGGER RAINFALL  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.  
 
AN ILL DEFINED WAVE ALONG 80W TO 12N DISSIPATED EARLY IN THE  
CYCLE.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
DAVISON...WPC (USA)  
 

 
 
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