734  
FXCA20 KWBC 141838  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
137 PM EST TUE NOV 14 2017  
 
TROPICAL DISCUSSION FROM NOV 14/12 UTC: MEANDERING MID/UPPER LEVEL  
RIDGE CONTINUES TO DOMINATE WESTERN PORTIONS OF THE DOMAIN WHILE  
CENTERING ON A CLOSED HIGH OVER SOUTHERN BAJA PENINSULA. THE RIDGE  
IS TO GENERALLY HOLD DURING THE NEXT FEW DAYS. ACROSS MEXICO THIS  
IS TO SUSTAIN A STRONG CAP INVERSION THAT IS TO INHIBIT ORGANIZED  
DEEP CONVECTION.  
 
AS THE RIDGE HOLDS TO THE WEST...IT IS TO STEER PROGRESSIVE SHORT  
WAVE PERTURBATIONS ACROSS THE EASTERN USA/WESTERN ATLANTIC TO THE  
NORTHERN CARIBBEAN ISLANDS. SHORT WAVE PERTURBATIONS ARE FORECAST  
TO EXIT THE USA AT AN INTERVAL OF EVERY 24-36 HRS. THESE ARE TO  
THEN COMBINE IN SUPPORT OF A BROAD TROUGH ACROSS THE WESTERN  
ATLANTIC TO THE NORTHERN CARIBBEAN ISLES. AT 250 HPA A SUBTROPICAL  
JET MAXIMA IS TO ROUND THE EASTERN FRINGES OF THE LONG WAVE  
TROUGH...WITH ITS RIGHT ENTRANCE REGION OVER HISPANIOLA TO  
GENERALLY FAVOR AN UPPER DIVERGENT PATTERN THAT IS TO VENT DEEP  
CONVECTION BETWEEN THE SOUTHEAST BAHAMAS/TURKS AND CAICOS-THE  
DOMINICAN REPUBLIC. AS THE TROUGH DEEPENS...IT IS TO PRESS AGAINST  
A CELL OF THE SUBEQUATORIAL RIDGE TO THE EAST. THE RIDGE EXTENDS  
OVER THE EASTERN CARIBBEAN-NORTHERN SOUTH AMERICA...FAVORING A  
MID/UPPER CONVERGENT PATTERN ACROSS THE ISLAND CHAIN-VIRGIN  
ISLES-PUERTO RICO. UNDER PRESSURE FROM THE TROUGH TO THE WEST THE  
RIDGE IS TO WEAKEN EARLY ON WEDNESDAY MORNING...RELAXING ITS  
FOOTHOLD OVER THE NORTHEAST CARIBBEAN ISLES. THIS WILL THEN ALLOW  
FOR DEEPER INSTABILITY TO GRADUALLY SPREAD FROM THE  
WEST-SOUTHWEST. SHORT WAVE VORTICES REVOLVING AROUND THE LONG WAVE  
AXIS ARE TO THEN LIFT ACROSS JAMAICA-HISPANIOLA...GRAZING  
NORTHWEST PORTIONS OF PUERTO RICO FROM TIME-TO-TIME. AT LOW LEVELS  
A FRONT IS TO MOVE ACROSS FLORIDA BY MIDDAY TODAY...REACHING THE  
NORTHWEST BAHAMAS LATER THIS EVENING/EARLY WEDNESDAY MORNING.  
DURING THE DAY ON WEDNESDAY THIS IS TO MEANDER ACROSS THE CENTRAL  
BAHAMAS-WESTERN CUBA...WHERE IT IS FORECAST TO GRADUALLY  
WEAKEN/DISSIPATE. A SECONDARY FRONT FOLLOWS...SURGING ACROSS  
FLORIDA ON WEDNESDAY EVENING...WEAKENING AS IT REACHES THE  
NORTHWEST BAHAMAS LATER ON THURSDAY. ACROSS THE CENTRAL  
BAHAMAS-WESTERN CUBA THESE ARE TO FAVOR SCATTERED CONVECTION WITH  
ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM ON TUESDAY AND  
WEDNESDAY. ON THURSDAY...AS A PREFRONTAL SHEAR LINE STREAMS ACROSS  
THE BAHAMAS...CONVECTION INCREASES TO 05-10MM/DAY AND MAXIMA OF  
15-25MM. ALSO AT LOW LEVELS...A RIDGE OVER THE SOUTHEAST USA  
FAVORS A BRISK NORTHEASTERLY FLOW ACROSS THE GULF OF MEXICO TO THE  
WESTERN CARIBBEAN/NORTHERN CENTRAL AMERICA. THIS FLOW IS ENHANCING  
LOW LEVEL MOISTURE CONVERGENCE ACROSS SOUTHERN MEXICO-NORTHERN  
HONDURAS. ACROSS SOUTHERN VERACRUZ-CHIAPAS IN SOUTHERN MEXICO THIS  
IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.  
ON WEDNESDAY THIS DECREASES TO 00-05MM/DAY AND MAXIMA OF 10MM.  
HIGHER AMOUNTS ARE FORECAST FOR NORTHERN HONDURAS WHERE WE EXPECT  
RAINFALL AMOUNTS OF 35-70MM/DAY AND MAXIMA OF 75-125MM. ON  
WEDNESDAY THIS DECREASES TO 10-15MM/DAY AND MAXIMA OF  
20-40MM...WHILE SIMULTANEOUSLY SPREADING WEST ACROSS BELIZE TO  
CENTRAL/NORTHERN GUATEMALA. ON THURSDAY EXPECTING ADDITIONAL  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM.  
 
OVER THE CARIBBEAN THE UPPER LEVEL TROUGH IS TO INTERACT WITH A  
TUTT INDUCED TROUGH OVER THE CENTRAL CARIBBEAN. THE LOW LEVEL AXIS  
EXTENDS ACROSS EASTERN CUBA-CENTRAL CARIBBEAN TO SOUTHERN CENTRAL  
AMERICA. UNDER INFLUENCE OF THIS FEATURE WINDS OVER THE EASTERN  
CARIBBEAN SHIFT TO THE SOUTH-SOUTHEAST TODAY...AND ON WEDNESDAY  
THEY WILL VEER TO THE SOUTH-SOUTHWEST. THIS WILL COINCIDE WITH  
WEAKENING OF TRADE WINDS CAP TO ALLOW FOR ADVECTION OF DEEP PLUME  
OF TROPICAL MOISTURE ACROSS THE NORTHERN CARIBBEAN...WITH MOISTURE  
POOLING ACROSS HISPANIOLA TO PUERTO RICO BY MIDMORNING ON  
WEDNESDAY. AS MOISTURE ADVECTS NORTH...ENVIRONMENTAL CONDITIONS  
ARE TO BECOME FAVORABLE FOR AN MCS TO FORM SOUTH OF HISPANIOLA  
EARLY ON THURSDAY MORNING. CONVECTION IS TO THEN CLUSTER BETWEEN  
THE HAITIAN PENINSULA/PORT AU PRINCE AREA AND ACROSS THE DOMINICAN  
REPUBLIC. IN THIS AREA INITIALLY EXPECTING RAINFALL AMOUNTS OF  
15-30MM/DAY AND MAXIMA OF 40-80MM. THROUGH THURSDAY THIS INCREASES  
TO 35-70MM/DAY AND MAXIMA OF 125-200MM. ACROSS PUERTO RICO  
INITIALLY EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF  
15MM IN ISOLATED CONVECTION...WITH MOST ACTIVE TO INITIALLY  
CLUSTER OVER NORTHWEST PORTIONS OF THE ISLAND. THROUGH  
WEDNESDAY...AS THE WINDS VEER TO THE SOUTH-SOUTHWEST...FOCUS OF  
THE CONVECTION WILL SHIFT TO NORTHEAST PUERTO RICO/SAN JUAN METRO  
AREA...WITH RAINFALL AMOUNTS INCREASING TO 10-15MM/DAY AND MAXIMA  
OF 20-30MM. ACROSS THE SOUTHEAST BAHAMAS-TURKS AND CAICOS AND  
EASTERN CUBA THIS IS TO INITIALLY FAVOR RAINFALL AMOUNTS OF  
15-30MM/DAY AND MAXIMA OF 40-80MM. IN WEDNESDAY THIS DECREASES TO  
10-15MM/DAY AND MAXIMA OF 20-35MM...WHILE ON THURSDAY EXPECTING  
ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM. THIS IS TO ALSO  
ENHANCE CONVECTION ACROSS JAMAICA TO FAVOR RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-20MM...INCREASING TO 10-15MM/DAY AND  
MAXIMA OF 20-35MM ON WEDNESDAY.  
 
THE MEANDERING LOW LEVEL TROUGH OVER THE CENTRAL CARIBBEAN IS TO  
ALSO SUSTAIN THE NORTHWARD MODULATION OF THE EASTERN PACIFIC ITCZ  
ACROSS THE ISTHMUS OF PANAMA TO THE SOUTHERN CARIBBEAN...WHERE IT  
IS TO REMAIN DURING THE NEXT FEW DAYS. THE ITCZ IS TO ENHANCE  
MOISTURE CONVERGENCE ACROSS WESTERN PANAMA AND EASTERN PORTIONS OF  
COSTA RICA...TO FAVOR RAINFALL AMOUNTS OF 35-70MM/DAY AND MAXIMA  
OF 75-150MM. THROUGH FRIDAY THE MAXIMA DECREASES TO 75-100MM. OVER  
SOUTHERN NICARAGUA AND ALONG THE BORDER WITH COSTA  
RICA...MEANWHILE...EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND  
MAXIMA OF 15-20MM. OVER COLOMBIA...AS THE ITCZ/NET MEANDERS NORTH  
OF ITS CLIMATOLOGICAL POSITION...EXPECTING DIURNAL CONVECTION ON  
THE ANDEAN REGION TO FAVOR RAINFALL AMOUNTS OF 15-20MM/DAY AND  
MAXIMA OF 25-50MM. ON WEDNESDAY-THURSDAY THIS DECREASES TO  
10-15MM/DAY AND MAXIMA OF 20-35MM. ON THE EASTERN PLAINS OF  
COLOMBIA-AMAZONIA AND AMAZONIA IN SOUTHERN VENEZUELA EXPECTING  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. OVER THE  
GUIANAS...MEANWHILE...MOST ACTIVE IS EXPECTED ALONG THE COAST...TO  
SUSTAIN 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  
54W 57W 60W 62W 64W 66W 68W 69W EW 20N  
62W 64W 66W 68W 70W DISSIPATES EW 14N  
 
AN EASTERLY WAVE ALONG 54W AND SOUTH OF 20N PULLS ACROSS SURINAME  
TO GUYANA EARLY ON WEDNESDAY MORNING...WHERE IT IS TO FAVOR  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. OVER THE  
SOUTHERN WINDWARD ISLANDS/TRINIDAD-NORTHEAST VENEZUELA IT IS TO  
SUSTAIN RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM ON  
WEDNESDAY... WHILE ACROSS VENEZUELA INTO COLOMBIA MOST ACTIVE  
CONVECTION IS EXPECTED TO THE SOUTH OF 07N...WHERE IT IS TO FAVOR  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM.  
 
AN EASTERLY WAVE ALONG 62W AND SOUTH OF 14N MOVES ACROSS CENTRAL  
TO WESTERN VENEZUELA TO EASTERN COLOMBIA ON WEDNESDAY. MOST ACTIVE  
CONVECTION...HOWEVER...IS EXPECTED TO THE SOUTH OF 07N...TO FAVOR  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. THE WAVE  
DISSIPATES LATER ON THURSDAY.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  
 

 
 
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