494  
FXCA20 KWBC 301830  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
229 PM EDT MON OCT 30 2017  
 
TROPICAL DISCUSSION FROM OCT 30/12 UTC: POLAR TROUGH EXITS THE  
EASTERN USA EARLY IN THE CYCLE. ON TUESDAY THE TROUGH IS FORECAST  
TO RAPIDLY LIFT OVER A BROAD RIDGE TO THE EAST. AT LOW LEVELS THE  
ASSOCIATED FRONT EXTENDS ACROSS THE TURKS-EASTERN CUBA...THEN INTO  
THE WESTERN CARIBBEAN JUST SOUTH OF THE CAYMAN ISLES TO  
BELIZE/GULF OF HONDURAS. ACROSS THE WESTERN CARIBBEAN THIS FAVORS  
BRISK NORTHEASTERLY WINDS OF 15-20KT THAT ARE CONVERGING ALONG THE  
COAST OF HONDURAS/NORTHEAST NICARAGUA. FRONTAL BOUNDARY IS TO  
REMAIN NEARLY STATIONARY THROUGH TUESDAY EVENING. ON WEDNESDAY  
MORNING...AS THE UPPER TROUGH PULLS...THE FRONT WILL RETROGRESS TO  
THE SOUTHEAST BAHAMAS-CENTRAL CUBA-CAYMAN ISLES TO THE WESTERN  
CARIBBEAN. LATER IN THE DAY IT REACHES THE CENTRAL BAHAMAS WHILE  
TRAILING END MEANDERS OVER CENTRAL CUBA TO THE NORTHWEST  
CARIBBEAN. ON THURSDAY MORNING THE FRONT WILL MOVE TO THE  
NORTHWEST BAHAMAS WHERE IT IS EXPECTED TO FRONTOLIZE.  
 
AS IT MEANDERS ACROSS THE TURKS/SOUTHEAST BAHAMAS-EASTERN CUBA  
THIS IS TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF  
10MM. ON TUESDAY IT INCREASES TO 05-10MM/DAY AND MAXIMA OF15MM. AS  
IT RETROGRESSES ACROSS THE CAYMAN ISLES ON WEDNESDAY MORNING  
EXPECTING A SURGE IN ACTIVITY...WITH ACCUMULATION OF 05-10MM/DAY  
AND MAXIMA OF 15-25MM. HIGHER AMOUNTS ARE EXPECTED OVER NORTHERN  
HONDURAS/NORTHEAST NICARAGUA...WHERE THE MEANDERING FRONT IS TO  
TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM ON  
MONDAY-TUESDAY. ON TUESDAY TO WEDNESDAY THIS DECREASES TO  
10-15MM/DAY AND MAXIMA OF 20-35MM...WHILE ON WEDNESDAY THE MAXIMA  
PEAKS AT 15-25MM. PREFRONTAL CONVECTION IS TO ALSO CLUSTER ACROSS  
JAMAICA...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND  
MAXIMA OF 15MM. ON TUESDAY TO WEDNESDAY THE MAXIMA INCREASES TO  
15-25MM.  
 
DOWNSTREAM FROM THE CONTINENTAL TROUGH...A MID/UPPER LEVEL RIDGE  
DOMINATES THE FLOW ACROSS THE WESTERN ATLANTIC...WITH AXIS  
CENTERING ON A 500 HPA HIGH TO THE NORTH-NORTHWEST OF PUERTO RICO.  
THROUGH WEDNESDAY EVENING THE HIGH WILL DRIFT TO THE  
WEST-SOUTHWEST...RELOCATING ACROSS HAITI TO EASTERN CUBA.  
MEANWHILE...UNDER THE INFLUENCE OF THIS FEATURE... A TRADE WINDS  
CAP IS TO ESTABLISH ACROSS THE NORTHEAST CARIBBEAN LATER ON  
TUESDAY. THIS IS TO GRADUALLY BUILD WEST ACROSS HISPANIOLA ON  
WEDNESDAY TO THURSDAY...TO SUSTAIN EROSION OF AVAILABLE MOISTURE.  
EARLY IN THE CYCLE PWAT CONTENT WILL PEAK AT 40-60MM. EARLY ON  
WEDNESDAY THE PWAT CONTENT DECREASES TO 20-30MM ACROSS PUERTO RICO  
AND THE VIRGIN ISLANDS. AT LOW LEVELS...A BROAD RIDGE BUILDS  
ACROSS THE EASTERN USA ON TUESDAY...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. GFS GDI FORECAST FOR THE PERIOD INITIALLY  
SHOWS FAVORABLE ENVIRONMENT FOR DEEP CONVECTION TO BUILD ACROSS  
PUERTO RICO-VIRGIN ISLES. OVER PUERTO RICO/VIRGIN ISLES AND  
EASTERN HISPANIOLA INITIALLY EXPECTING RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-20MM. AS THE TRADE WINDS CAP  
STRENGTHENS ON WEDNESDAY THIS DECREASES TO 00-05MM/DAY IN ISOLATED  
CONVECTION. ACROSS HISPANIOLA EXPECTING RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-20MM  
 
FARTHER SOUTH...ITCZ IS TO MEANDER EAST ACROSS COSTA RICA-PANAMA  
TO NORTHERN COLOMBIA. AS IT MEANDERS ACROSS SOUTHERN CENTRAL  
AMERICA THIS IS TO FAVOR SCATTERED DEEP CONVECTION WITH  
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-30MM. ON  
TUESDAY-WEDNESDAY IT IS TO THEN FAVOR RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS COLOMBIA-NORTHWEST  
VENEZUELA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF  
15-30MM. ON TUESDAY-WEDNESDAY THE DAILY MAXIMA IS TO PEAK AT  
15-20MM. OVER CENTRAL-EASTERN VENEZUELA DIURNAL CONVECTION ALONG  
THE NEAR EQUATORIAL TROUGH WILL SUSTAIN RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-30MM. OVER THE ATLANTIC...ITCZ  
REMAINS NORTH OF THE GUIANAS. MOST ACTIVE IS EXPECTED ACROSS  
GUYANA...WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF  
15-20MM.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
45W 47W 49W 50W 52W 54W DISSIPATES TUTT INDCD 14N  
56W 57W 58W 60W 62W 64W 67W 69W TW 14N  
76W 77W 78W 80W DISSIPATES TW 12N  
 
A DEEP TUTT TO THE EAST OF THE SUBTROPICAL RIDGE SUSTAINS AN  
INDUCED TROUGH IN THE EASTERLY TRADES...WITH AXIS ALONG 45W. THIS  
MEANDERS WEST INTO NORTHERN FRENCH GUIANA ON TUESDAY  
AFTERNOON...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY  
IN ISOLATED AND MAXIMA OF 10MM. THE PERTURBATION IS TO THEN  
WEAKEN/DISSIPATE ON THURSDAY MORNING.  
 
A TROPICAL WAVE ALONG 56W AND SOUTH OF 14N IS TO SUSTAIN SCATTERED  
CONVECTION ACROSS THE SOUTHERN WINDWARD  
ISLES-TRINIDAD/TOBAGO-ORINOCO DELTA REGION EARLY ON TUESDAY...WITH  
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ACROSS CENTRAL  
TO SOUTHERN VENEZUELA IT IS TO INTERACT WITH THE NEAR EQUATORIAL  
TROUGH TO TRIGGER RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF  
20-35MM ON WEDNESDAY.  
 
ILL DEFINED WAVE ALONG 76W TO 12N IS FORECAST TO DISSIPATE EARLY  
ON WEDNESDAY MORNING. MEANWHILE...ACROSS WESTERN COLOMBIA TO THE  
DARIEN IN EASTERN PANAMA THIS IS TO SUSTAIN RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-30MM. ON TUESDAY IT DECREASES TO  
05-10MM/DAY AND MAXIMA OF 15-20MM.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
DAVISON...WPC (USA)  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page