503  
FXCA20 KWBC 151909  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
208 PM EST WED NOV 15 2017  
 
TROPICAL DISCUSSION FROM NOV 15/12 UTC: A 500/250 HPA HIGH OVER  
SOUTHERN BAJA PENINSULA IS TO ANCHOR A MID/UPPER LEVEL RIDGE  
ACROSS MEXICO INTO THE EASTERN PACIFIC. THROUGH FRIDAY EVENING THE  
HIGH RELOCATES TO CENTRAL MEXICO...WHILE THE RIDGE BUILDS EAST  
ACROSS THE GULF TO THE SOUTHERN USA. THE RIDGE ALOFT SUSTAINS A  
FAIRLY STRONG SUBSIDENCE CAP ACROSS CENTRAL-NORTHERN STATES OF  
MEXICO...WHERE IT IS TO INHIBIT ORGANIZED DEEP CONVECTION DURING  
THE NEXT FEW DAYS.  
 
THE MEANDERING MID/UPPER LEVEL RIDGE CONTINUES TO STEER SHORT WAVE  
PERTURBATIONS ACROSS THE SOUTHEAST USA TO THE WESTERN ATLANTIC.  
THE INFLOW OF SHORT WAVE ENERGY WILL HELP SUSTAIN A LONG WAVE  
TROUGH TO THE EAST. THE TROUGH IS TO EXTEND OVER THE WESTERN  
ATLANTIC...ACROSS CUBA TO THE WESTERN CARIBBEAN. THE UPPER LEVEL  
TROUGH REACHES MAXIMUM AMPLITUDE LATER ON THURSDAY/EARLY ON FRIDAY  
MORNING. AT 250 HPA...A SUBTROPICAL JET MAXIMA IS TO THEN EXTEND  
FROM THE WESTERN CARIBBEAN/NORTHERN HONDURAS...ACROSS  
JAMAICA/HAITI TO THE WESTERN ATLANTIC. ACROSS HISPANIOLA THIS IS  
TO FAVOR AN UPPER DIVERGENT PATTERN THAT IS TO VENT DEEP  
CONVECTION. A CELL OF THE SUBEQUATORIAL RIDGE LIES TO THE  
EAST...EXTENDING OVER THE ISLAND CHAIN TO THE EASTERN  
CARIBBEAN...FAVORING A TRADE WINDS CAP ACROSS PUERTO RICO AND THE  
ISLAND CHAIN. UNDER PRESSURE FROM THE AMPLIFYING TROUGH...THE  
RIDGE RELAXES ITS FOOTHOLD OVER PUERTO RICO/VIRGIN ISLES EARLY  
THIS AFTERNOON...WITH ENVIRONMENTAL CONDITIONS BECOMING MORE  
FAVORABLE FOR DEEP CONVECTION TO DEVELOP. SHORT WAVE PERTURBATIONS  
ROUNDING THE LONG WAVE TROUGH ARE TO THEN LIFT ACROSS THE CENTRAL  
CARIBBEAN-HISPANIOLA...WHILE GRAZING NORTHWEST PORTIONS OF PUERTO  
RICO. THIS WILL PROVIDE THE DYNAMICAL SUPPORT TO CONVECTION ACROSS  
THE NORTHERN CARIBBEAN DURING THE NEXT FEW DAYS.  
 
AT LOW LEVELS...MEANDERING FRONT IS TO EXTEND OVER THE  
BAHAMAS-CUBA LATER TODAY...WHERE IT IS FORECAST TO FRONTOLIZE  
EARLY ON THURSDAY. A SECONDARY FRONT FOLLOWS...SURGING ACROSS  
FLORIDA ON WEDNESDAY EVENING. THE FRONT CONTINUES TO THE NORTHWEST  
BAHAMAS ON THURSDAY...WHERE IT IS EXPECTED TO STALL. THIS WILL  
THEN DISSIPATE DURING THE WEEKEND. AS IT SURGES ACROSS THE BAHAMAS  
THIS WILL SUSTAIN A PREFRONTAL SHEAR LINE ACROSS THE CENTRAL  
BAHAMAS TO WESTERN CUBA. THIS MOVES TO THE SOUTHEAST  
BAHAMAS-EASTERN CUBA ON FRIDAY EVENING. MOST ACTIVE CONVECTION IS  
EXPECTED IN ASSOCIATION WITH THE SHEAR LINE. OVER THE NORTHWEST  
BAHAMAS THE SHEAR LINE WILL SUSTAIN RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-25MM...WHILE ACROSS CENTRAL/WESTERN  
CUBA THIS IS TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA  
OF 10MM. AS IT MOVES TO EASTERN CUBA-SOUTHEAST BAHAMAS/THE TURKS  
ON FRIDAY IT IS TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND  
MAXIMA OF 20-35MM. ALSO AT LOW LEVELS...A RIDGE LIES TO THE  
WEST...FAVORING A BRISK NORTHEASTERLY FLOW ACROSS THE GULF OF  
MEXICO TO THE WESTERN CARIBBEAN/NORTHERN CENTRAL AMERICA. ACROSS  
SOUTHERN VERACRUZ-CHIAPAS IN SOUTHERN MEXICO THIS IS TO FAVOR  
LIGHT CONVECTION WITH ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF  
10MM THROUGH THURSDAY MORNING. ON THURSDAY-FRIDAY THIS WILL FAVOR  
RAINFALL AMOUNTS OF 05-10MMD/AY AND MAXIMA OF 15MM. HIGHER AMOUNTS  
ARE FORECAST FOR NORTHERN HONDURAS...WITH ACCUMULATION OF  
10-15MM/DAY AND MAXIMA OF 20-40MM. EARLY IN THE PERIOD THIS  
SPREADS WEST ACROSS NORTHERN GUATEMALA/SOUTHERN BELIZE TO SUPPORT  
SIMILAR RAINFALL AMOUNTS. ON THURSDAY-FRIDAY THIS DECREASES TO  
05-10MM/DAY AND MAXIMA OF 15MM.  
 
THE BROAD POLAR TROUGH OVER THE WESTERN ATLANTIC IS PHASING WITH A  
LOW LEVEL TROUGH OVER THE CENTRAL CARIBBEAN. EARLY IN THE CYCLE  
THE TROUGH IS TO EXTEND FROM EASTERN CUBA/JAMAICA TO COSTA  
RICA/WESTERN PANAMA. THIS IS TO REMAIN NEARLY STATIONARY THROUGH  
THURSDAY EVENING. ON FRIDAY...AS RIDGE OVER THE GULF OF MEXICO  
BUILDS...THE TROUGH IS TO MOVE EAST ACROSS HAITI TO THE GULF OF  
URABA/EASTERN PANAMA. THE TROUGH SUSTAINS A MOIST ADVECTIVE  
PATTERN...WITH DEEP PLUME OF TROPICAL MOISTURE LIFTING ACROSS THE  
CENTRAL CARIBBEAN TO SOUTHERN HISPANIOLA-PUERTO RICO/VIRGIN ISLES.  
IN THIS AREA PWAT CONTENT IS TO RANGE BETWEEN 50-75MM DURING THE  
NEXT FEW DAYS. FAVORABLE JET DYNAMICS ACROSS HISPANIOLA AND INFLOW  
OF MID LEVEL VORTICES WILL PRIME THE AREA FOR GENERATION OF MESO  
SCALE CONVECTIVE SYSTEMS. ACROSS SOUTHERN HISPANIOLA EXPECTING  
RAINFALL AMOUNTS OF 30-70MM/DAY AND MAXIMA OF 125-150MM ON  
WEDNESDAY...WHILE ON THURSDAY EXPECTING RAINFALL AMOUNTS OF  
35-70MM/DAY AND MAXIMA OF 125-200MM. ON FRIDAY...THE FOCUS OF THE  
HEAVY CONVECTION GRADUALLY SHIFTS TO THE DOMINICAN SIDE OF THE  
ISLAND...WHERE IT WILL SUSTAIN RAINFALL AMOUNTS OF 20-40MM/DAY AND  
MAXIMA OF 50-100MM. ALTHOUGH THE MOIST PLUME IS TO ALSO ENVELOP  
PUERTO RICO AND THE VIRGIN ISLES...LACKING MID LEVEL  
FORCING...DIURNAL CONVECTION IS TO RESULT IN RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-30MM. THROUGH FRIDAY THIS INCREASES  
TO 10-15MM/DAY AND MAXIMA OF 20-45MM. OVER JAMAICA...MEANWHILE...  
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.  
ON THURSDAY TO FRIDAY THIS DECREASES TO 00-05MM/DAY AND MAXIMA OF  
10MM.  
 
THE CARIBBEAN TROUGH CONTINUES TO INTERACT WITH THE EASTERN  
PACIFIC ITCZ...DRAWING THE CONVERGENCE ZONE NORTH ACROSS WESTERN  
PANAMA TO THE SOUTHERN CARIBBEAN. ACROSS NORTHERN COSTA  
RICA/SOUTHERN NICARAGUA DIURNAL CONVECTION IS TO RESULT IN  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MMM. OVER  
EASTERN COSTA RICA TO WESTERN PANAMA EXPECT HIGHER RAINFALL  
AMOUNTS OF 35-70MM/DAY AND MAXIMA OF 75-125MM THROUGH THURSDAY  
MORNING. ON THURSDAY TO FRIDAY EXPECTING RAINFALL AMOUNTS OF  
35-70MM/DAY AND MAXIMA OF 75-100MM. ON FRIDAY THIS DECREASES TO  
05-10MM/DAY AND MAXIMA OF 15MM. OVER WESTERN COLOMBIA/ANDEAN  
REGION...AS THE ITCZ MEANDERS NORTH OF ITS CLIMATOLOGICAL  
POSITION...DIURNAL CONVECTION IS TO FAVOR RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-35MM. ON FRIDAY...AS THE LOW LEVEL  
TROUGH MOVES TO THE GULF OF URABA...EXPECTING HIGHER RAINFALL  
AMOUNTS OVER NORTHERN COLOMBIA TO EASTERN PANAMA WITH ACCUMULATION  
OF 15-20MM/DAY AND MAXIMA OF 30-60MM. ACROSS VENEZUELA EXPECTING  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
60W 62W 64W 66W 68W 69W 70W 71W EW 19N  
65W 67W 68W DISSIPATES EW 12N  
 
AN EASTERLY WAVE ALONG 60W AND SOUTH OF 19N IS TO ONLY TRIGGER  
LIGHT CONVECTION ACROSS THE WINDWARD ISLES-NORTHEAST  
VENEZUELA...WITH ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM.  
ON THURSDAY...AS IT MOVES ACROSS CENTRAL VENEZUELA...IT IS TO  
FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. THIS  
SPREADS TO EASTERN COLOMBIA ON FRIDAY TO SUSTAIN RAINFALL AMOUNTS  
OF 05-10MM/DAY AND MAXIMA OF 15MM.  
 
AN ILL ORGANIZED EASTERLY WAVE ALONG 65W IS FORECAST TO DISSIPATE  
EARLY ON THURSDAY MORNING. MEANWHILE...ACROSS WESTERN  
VENEZUELA/EASTERN COLOMBIA EXPECTING RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-25MM.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  
 

 
 
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