909  
FXCA20 KWBC 221849  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
149 PM EST WED NOV 22 2017  
 
TROPICAL DISCUSSION FROM NOV 22/12 UTC: WEST OVER THE DOMAIN...A  
LONG WAVE TROUGH EXTENDS FROM THE EASTERN USA TO THE GULF/SOUTHERN  
STATES OF MEXICO. A JET ROUNDING THE BASE OF THE TROUGH ON  
THURSDAY-FRIDAY IS TO SLOWLY PULL THIS AXIS EAST OVER FLORIDA TO  
THE YUCATAN/WESTERN CARIBBEAN LATER ON FRIDAY. ALTHOUGH IT  
MEANDERS EAST...THE HIGHLY AMPLIFIED LONG WAVE PATTERN IS TO HOLD  
THROUGH THE WEEKEND. AT LOW LEVELS...THE TROUGH ALOFT SUSTAINS A  
FRONT ACROSS FLORIDA-A SURFACE LOW OVER THE CENTRAL GULF OF MEXICO  
TO TAMAULIPAS. THE LOW IS TO MEANDER EAST ACROSS THE GULF INTO  
CENTRAL FLORIDA LATER ON THURSDAY. MEANWHILE...THIS IS TO SUSTAIN  
BRISK NORTHERLY WINDS ACROSS THE WESTERN GULF...WITH BOUNDARY  
LAYER WINDS OF 35-40KT ALONG THE GULF COAST OF MEXICO LATER TODAY.  
THIS IS TO THEN SUSTAIN A TEHUANTEPECER JET OF 40-45KT ON THURSDAY  
TO FRIDAY. AS THE WINDS INTENSIFY...THE FRONT SURGES ACROSS  
VERACRUZ MEXICO LATER TODAY...AND ON THURSDAY MORNING IT REACHES  
THE SOUTHERN STATE OF CHIAPAS. ON THURSDAY TO FRIDAY THIS BOUNDARY  
MOVES OVER THE YUCATAN...NEARING THE NORTHWEST BAHAMAS-WESTERN  
CUBA EARLY ON SATURDAY MORNING. THE STRONG NORTHERLIES OVER  
SOUTHERN MEXICO ARE TO FAVOR SCATTERED CONVECTION ACROSS NORTHERN  
CHIAPAS-SOUTHERN VERACRUZ...WITH ACCUMULATION OF 10-15MM/DAY AND  
MAXIMA OF 20-30MM. ON THURSDAY-FRIDAY THIS DECREASES TO  
05-10MM/DAY AND MAXIMA OF 15-20MM... WHILE ON FRIDAY EXPECTING  
ADDITIONAL RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.  
OVER CAMPECHE/YUCATAN EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY  
AND MAXIMA OF 15MM TODAY THROUGH THURSDAY. AS IT ENTERS THE  
NORTHWEST BAHAMAS-CUBA ON SATURDAY MORNING EXPECTING RAINFALL  
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.  
 
A MID/UPPER LEVEL RIDGE TO THE EAST...MEANWHILE...EXTENDS FROM  
NORTHERN VENEZUELA/ EASTERN CARIBBEAN TO THE WESTERN ATLANTIC. AT  
500 HPA THE RIDGE IS TO CENTER ON A CLOSED HIGH OVER PUERTO RICO  
LATER THIS AFTERNOON...TO THEN MEANDER NORTH-NORTHEAST OF THE  
ISLAND ON THURSDAY-FRIDAY. AS IT MEANDERS OVER THE EASTERN  
CARIBBEAN ISLES THE MID LEVEL RIDGE SUSTAINS A STRONG SUBSIDENCE  
CAP THAT IS INHIBITING ORGANIZED DEEP CONVECTION. AT LOW  
LEVELS...BROAD RIDGE DOMINATES THE FLOW ACROSS THE WESTERN  
ATLANTIC TO THE NORTHERN CARIBBEAN. THIS FAVORS A BRISK EASTERLY  
FLOW ACROSS THE ISLAND CHAIN TO THE CENTRAL CARIBBEAN...WITH 850  
HPA WINDS PEAKING AT 15-20KT. POLAR FRONTS EXITING THE EASTERN USA  
ARE TO PRESS AGAINST THIS RIDGE...WITH AXIS TO WEAKEN WHILE  
RELOCATING TO THE CENTRAL ATLANTIC EARLY IN THE CYCLE. EASTERLY  
TRADES ARE TO PERSIST ACROSS THE BASIN...WITH WINDS PEAKING AT  
10-15KT. EXCEPT FOR TRINIDAD/TOBAGO AND THE GRENADINES...EXPECTING  
FAIR WEATHER CONDITIONS TO GENERALLY PREVAIL ACROSS THE ISLAND  
CHAIN-PUERTO RICO-HISPANIOLA. OVER TRINIDAD AND TOBAGO ITCZ  
RELATED CONVERGENCE ON THURSDAY-FRIDAY IS TO RESULT IN RAINFALL  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.  
 
ALSO AT LOW LEVELS...AN INVERTED TROUGH OVER THE CARIBBEAN EXTENDS  
NORTH ALONG 80W BETWEEN COSTA RICA/WESTERN PANAMA TO EASTERN CUBA.  
FRONTAL LOW OVER THE GULF OF MEXICO PHASES WITH THIS PERTURBATION  
ON THURSDAY...WITH AXIS BECOMING SOMEWHAT BETTER ORGANIZED WHILE  
MERGING WITH AN INDUCED/PREFRONTAL TROUGH. THIS IS TO ALSO SUSTAIN  
GRADUAL INTENSIFICATION OF THE PANAMANIAN LOW TO THE SOUTH OF THE  
ISTHMUS. THE LOW IS TO SUSTAIN A WESTERLY FLOW ACROSS THE EASTERN  
PACIFIC TO THE EJE CAFETERO IN WESTERN COLOMBIA...WHERE IT IS TO  
ENHANCE COASTAL CONVERGENCE. OVER THE BAHAMAS-TURKS THIS IS TO  
FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. ON  
THURSDAY IT DECREASES TO 00-05MM/DAY AND MAXIMA OF 10MM ACROSS THE  
CAYMAN ISLES EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA  
OF 15MM. THROUGH FRIDAY IT INCREASES TO 10-15MM/DAY AND MAXIMA OF  
20-30MM. ACROSS JAMAICA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY  
AND MAXIMA OF 20-40MM. ON THURSDAY THE MAXIMA DECREASES TO  
20-30MM. OVER PANAMA-COSTA RICA THIS IS TO INTERACT WITH THE ITCZ  
IN SUPPORT OF SCATTERED CONVECTION...WITH ACCUMULATION OF  
10-15MM/DAY AND MAXIMA OF 20-30MM. THROUGH FRIDAY THIS IS FORECAST  
TO INCREASES TO 15-20MM/DAY AND MAXIMA OF 25-50MM. OTHER  
CONVECTION OVER THE CENTRAL CARIBBEAN IS TO AFFECT ISLA DE  
PROVIDENCIA AND SAN ANDRES WITH RAINFALL AMOUNTS OF 10-15MM/DAY  
AND MAXIMA OF 20-30MM.  
 
UNDER INFLUENCE OF THE PANAMANIAN LOW...AND LONG FETCH WESTERLY  
FLOW...HIGHER AMOUNTS ARE EXPECTED OVER WESTERN COLOMBIA. IN THIS  
AREA EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF  
30-60MM DURING THE NEXT FEW DAYS. OTHER CONVECTION IS EXPECTED  
BETWEEN AMAZONIA IN SOUTHERN VENEZUELA AND THE PIEDEMONTE LLANERO  
OVER EASTERN COLOMBIA. IN THIS AREA EXPECT RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-35MM. THIS DECREASES TO 05-10MM/DAY  
AND MAXIMA OF 15-20MM ON THURSDAY-FRIDAY.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE  
SOF  
50W 52W 55W 58W 60W 64W 67W 70W EW  
15N  
55W 57W 59W 61W 63W 66W 69W 71W TUTT-INDCD  
26N  
65W 67W 69W 71W 73W 76W 79W 81W EW  
16N  
 
AN EASTERLY WAVE ALONG 50W AND SOUTH OF 15N SUSTAINS SCATTERED  
CONVECTION ALONG THE ITCZ TO THE NORTH. OVER FRENCH GUIANA TO  
SURINAME THIS IS TO ONLY TRIGGER LIGHT CONVECTION WITH  
ACCUMULATION OF 00-05MM/DAY. EARLY ON FRIDAY IT MOVES ACROSS  
NORTHERN GUYANA TO NORTHEAST VENEZUELA-TRINIDAD/TOBAGO-SOUTHERN  
WINDWARD ISLES. IN THIS AREA IT IS TO SUSTAIN RAINFALL AMOUNTS OF  
05-10MM/DAY AND MAXIMA OF 15-20MM. THEREAFTER MOST ACTIVE IS  
EXPECTED ACROSS SOUTHERN-CENTRAL VENEZUELA TO EASTERN  
COLOMBIA...WHERE IT IS TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY  
AND MAXIMA OF 15-25MM.  
 
A TUTT INDUCED PERTURBATION IN THE EASTERLY TRADES EXTENDS ALONG  
55W AND NORTH OF 17N. THIS REACHES THE NORTHEAST CARIBBEAN LATER  
ON THURSDAY...CROSSING THE VIRGIN ISLES TO EASTERN PUERTO RICO ON  
FRIDAY. A PLUME OF SHALLOW MOISTURE ACCOMPANIES THIS WAVE. AS IT  
ENTERS THE EASTERN CARIBBEAN...THE MEANDERING MID LEVEL RIDGE AND  
ASSOCIATED TRADE WINDS ARE TO CAP MOISTURE TO ATMOSPHERE BELLOW  
700-600 HPA. ACROSS THE NORTHERN LEEWARD/VIRGIN ISLES TO PUERTO  
RICO THIS IS TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND ISOLATED  
MAXIMA OF 10MM ON THURSDAY-FRIDAY. SIMILAR AMOUNTS ARE EXPECTED  
ACROSS THE DOMINICAN REPUBLIC ON FRIDAY TO SATURDAY.  
 
AN EASTERLY WAVE ALONG 65W AND SOUTH OF 16N IS TO ENHANCE  
CONVECTION ACROSS SOUTHERN VENEZUELA OVER THE NEXT DAY OR SO...TO  
FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ON  
THURSDAY...ACROSS EASTERN COLOMBIA/WESTERN VENEZUELA...THIS IS TO  
THEN FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.  
ACROSS WESTERN COLOMBIA THIS INCREASES TO 15-20MM/DAY AND MAXIMA  
OF 30-60MM LATER ON THURSDAY/FRIDAY MORNING.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  
 

 
 
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