390  
FXCA20 KWBC 231844  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
244 PM EDT MON OCT 23 2017  
 
TROPICAL DISCUSSION FROM OCT 23/12 UTC: DEEPENING POLAR TROUGH IS  
TO DOMINATE THE FLOW ACROSS WESTERN PORTIONS OF THE DOMAIN...WITH  
MID LEVEL TROUGH AXIS TO AMPLIFY ACROSS THE CENTRAL/EASTERN USA TO  
THE NORTHERN GULF OF MEXICO LATER ON TUESDAY. AT LOW LEVELS THIS  
SUSTAINS A SURFACE FRONT THAT MOVES ACROSS NORTHERN FLORIDA-THE  
GULF OF MEXICO TO THE STATE OF VERACRUZ LATER TODAY. ON TUESDAY  
MORNING THE FRONT WILL MOVE TO CENTRAL FLORIDA...TRAILING ACROSS  
THE YUCATAN TO VERACRUZ. THIS WILL BE ACCOMPANIED BY A NORTHERLY  
WIND SURGE OF 20-30KT...AND AN ENSUING TEHUANTEPECER JET OF 50KT.  
BUILDING POLAR RIDGE IS TO THEN DISPLACE THE FRONT FARTHER EAST  
AND SOUTH...WITH THE FRONT RACING ACROSS FLORIDA TO THE NORTHWEST  
BAHAMAS-WESTERN CUBA LATER ON WEDNESDAY. A PREFRONTAL SHEAR LINE  
IS TO ACCOMPANY THE SURFACE FRONT AS IT RACES ACROSS THE GULF...TO  
MOVE OVER THE YUCATAN-BELIZE/GUATEMALA LATER TODAY...TO THEN  
MEANDER OVER THE GULF OF HONDURAS ON TUESDAY-EARLY WEDNESDAY.  
LATER IN THE CYCLE IT IS TO MEANDER ACROSS CUBA TO THE CAYMAN  
ISLES-NORTHEASTERN HONDURAS. THE FRONT AND STRONG FRONTAL  
NORTHERLIES WILL COMBINE WITH ANOMALOUSLY WARM SEA SURFACE  
TEMPERATURES ACROSS THE GULF OF MEXICO TO FAVOR HEAVY RAINFALL  
AMOUNTS. MOST INTENSE ARE EXPECTED ACROSS SOUTHERN  
VERACRUZ-CHIAPAS IN SOUTHERN MEXICO AND CENTRAL GUATEMALA...WITH  
ACCUMULATION OF 50-10MM/DAY AND MAXIMA OF 150-250MM EXPECTED  
THROUGH TUESDAY MORNING. ON TUESDAY TO WEDNESDAY...AS THE WINDS  
INTENSIFY...HEAVY CONVECTION IS TO SPREAD ACROSS CHIAPAS TO  
CENTRAL GUATEMALA WHERE IT IS TO FAVOR SIMILAR RAINFALL AMOUNTS.  
OVER THE YUCATAN PENINSULA PREFRONTAL CONVECTION IS TO TRIGGER  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM EARLY IN THE  
CYCLE. ON TUESDAY THIS INTENSIFIES TO 15-20MM/DAY AND MAXIMA OF  
30-60MM. OVER BELIZE-NORTHERN HONDURAS/CENTRAL GUATEMALA THE SHEAR  
LINE WILL SUSTAIN RAINFALL AMOUNTS OF 25-50MM/DAY AND MAXIMA OF  
75-125MM EARLY ON TUESDAY. ON TUESDAY-WEDNESDAY THIS INCREASES TO  
50-100MM/DAY AND MAXIMA OF 150-250MM. OVER THE NORTHWEST BAHAMAS  
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM  
WEDNESDAY TO THURSDAY...WHILE ACROSS WESTERN CUBA EXPECTING  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.  
 
AS THE POLAR TROUGH DEEPENS ACROSS THE GULF OF MEXICO IT IS TO  
INTERACT WITH A LOW/TROUGH OVER THE SOUTHERN CARIBBEAN. GLOBAL  
MODELS AGREE ON THIS LOW LIFTING ALONG THE COAST OF NICARAGUA.  
THIS WILL THEN DRAW THE ITCZ NORTH OF ITS CLIMATOLOGICAL POSITION  
ACROSS THE CENTRAL CARIBBEAN...WITH PLUME OF DEEP TROPICAL  
MOISTURE REACHING JAMAICA ON WEDNESDAY. ACROSS COSTA RICA-SOUTHERN  
NICARAGUA EXPECTING ITCZ RELATED CONVERGENCE TO TRIGGER RAINFALL  
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM. ON TUESDAY-WEDNESDAY  
IT INCREASES TO 20-30MM/DAY AND MAXIMA OF 50-100MM...WHILE ON  
WEDNESDAY THE MAXIMA PEAKS AT 75-125MM. OVER EASTERN  
NICARAGUA/NORTHEAST HONDURAS EXPECTING RAINFALL AMOUNTS OF  
25-50MM/DAY AND MAXIMA OF 75-125MM. LATER IN THE CYCLE...AS DEEP  
TROPICAL MOISTURE SURGES ACROSS THE CENTRAL CARIBBEAN...THIS IS TO  
FAVOR SCATTERED CONVECTION ACROSS WESTERN JAMAICA WITH RAINFALL  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM. OVER NORTHERN  
COLOMBIA/NORTHWEST VENEZUELA EXPECT RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-40MM THROUGH TUESDAY MORNING. THROUGH  
WEDNESDAY IT DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-25MM.  
HIGHER AMOUNTS ARE EXPECTED ALONG THE WEST COAST OF  
COLOMBIA/ANDEAN REGION EARLY IN THE PERIOD...WITH ACCUMULATION OF  
15-20MM/DAY AND MAXIMA OF 30-60MM. THROUGH WEDNESDAY...AS THE LOW  
LEVEL WINDS BACK TO THE SOUTH-SOUTHEAST...IT DECREASES TO  
05-10MM/DAY AND MAXIMA OF 15-25MM.  
 
SOUTH OF THE AMPLIFYING POLAR TROUGH...A BROAD UPPER LEVEL RIDGE  
EXTENDS ACROSS CENTRAL AMERICA-WESTERN CARIBBEAN. A TUTT TO THE  
EAST EXTENDS SOUTH FROM A CLOSED LOW NORTH OF PUERTO RICO/VIRGIN  
ISLES TO THE EASTERN CARIBBEAN/NORTHEAST VENEZUELA. AS THE POLAR  
TROUGH TO THE NORTH DEEPENS...IT WILL DISPLACE THE RIDGE TO THE  
EAST. THIS...IN-TURN...PUSHES THE TUTT TO EAST ACROSS THE LESSER  
ANTILLES LATER ON WEDNESDAY. MEANWHILE...THE TROUGH IS TO INTERACT  
WITH THE ITCZ AS IT MEANDERS OVER THE GRENADINES-TRINIDAD/TOBAGO  
TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF  
20-30MM...WITH SIMILAR AMOUNTS ACROSS NORTHERN GUYANA. OVER  
VENEZUELA MOST ACTIVE CONVECTION IS EXPECTED ACROSS AMAZONIA TO  
THE SOUTH...WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-30MM  
EARLY IN THE CYCLE...INCREASING TO 20-40MM ON TUESDAY.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE SOF  
43W 46W 49W 52W 54W 57W 59W 61W TW 10N  
56W 58W 60W 62W 64W 66W 68W 70W TW 15N  
58W 60W 63W 65W 67W DISSIPATES TUTT-IND 22N  
87W 89W 91W DISSIPATES TW 21N  
 
TROPICAL WAVE ALONG 43W AND SOUTH OF 10N REACHES NORTHERN FRENCH  
GUIANA ON TUESDAY TO FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND  
MAXIMA OF 10MM. ACROSS SURINAME-GUYANA THIS IS TO THEN TRIGGER  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM ON WEDNESDAY.  
 
TROPICAL WAVE ALONG 56W AND SOUTH OF 15N IS TO TRIGGER SCATTERED  
CONVECTION ACROSS NORTHERN GUYANA-NORTHEAST  
VENEZUELA-GRENADINES/TRINIDAD AND TOBAGO...TO SUSTAIN RAINFALL  
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. AS IT PULLS ACROSS  
EASTERN VENEZUELA THIS IS TO THEN TRIGGER SIMILAR RAINFALL  
AMOUNTS...WHILE OVER THE ABC ISLANDS EXPECTING ACCUMULATION OF  
00-05MM/DAY AND MAXIMA OF 10MM.  
 
DEEP TUTT OVER THE EASTERN CARIBBEAN SUSTAIN AN INDUCED TROUGH IN  
THE EASTERLY TRADES WITH AXIS NORTH ALONG 58W. THIS MOVES OVER THE  
FRENCH ISLANDS EARLY ON TUESDAY TO FAVOR RAINFALL AMOUNTS OF  
10-15MM/DAY AND MAXIMA OF 20-40MM...WHILE ACROSS THE  
LEEWARD-VIRGIN ISLANDS EXPECTING ACCUMULATION OF 00-05MM/DAY AND  
MAXIMA OF 10MM.  
 
WANING TROPICAL WAVE EXTENDS ALONG 87W TO 21N. THIS IS MERGING  
INTO A PREFRONTAL TROUGH OVER THE WESTERN CARIBBEAN/THE  
YUCATAN...AND AS A RESULT IT IS EXPECTED TO QUICKLY DISSIPATE.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
DAVISON...WPC (USA)  

 
 
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