000
AXPZ20 KNHC 182120
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT OCT 18 2008

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...ITCZ...
THE ITCZ AXIS IS ALONG THE LINE 06N77W TO 06N105W TO 09N130W TO 
08N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION  
WITHIN 100 NM OF THE COAST OF COLOMBIA SOUTH IS DIMINISHING.
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 60 NM OF THE 
POINT 17.5N105W...THIS CONVECTION IS WELL NORTH OF THE ITCZ. 
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM OF THE POINT 
09N132W. THE LOW ANALYZED NEAR 11N137W 1012 MB HAS BEEN 
ASSOCIATED WITH A TROUGH EMBEDDED IN THE ITCZ BUT IS NOW 
ANALYZED NORTH OF THE ITCZ. THE LOW IS FORECAST TO DISSIPATE IN 
24 HOURS. A FEW THUNDERSTORMS ARE LOCATED WITHIN 240 NM OF THE 
CENTER MAINLY IN THE NORTH SEMICIRCLE.

...DISCUSSION...
GALE FORCE WINDS HAVE BEGUN IN THE GULF OF TEHUANTEPEC AS THE 
PRESSURE GRADIENT BUILDS ACROSS THE REGION BETWEEN THE SURFACE 
HIGH PRESSURE SURGING DOWN THE MEXICAN GULF OF MEXICO COAST AND 
A BROAD LOW PRESSURE AREA THAT EXTENDS FROM THE GULF OF 
HONDURAS WEST SOUTHWESTWARD TO A LOW NEAR 11N92W 1010 MB. THESE 
SYSTEMS ARE FORECAST TO CHANGE LITTLE THROUGH 24 TO 48 HOURS 
WITH THE GALE CONDITIONS CONTINUING THROUGH SUNDAY THEN SLOWLY 
DIMINISHING THROUGH MONDAY. 

ELSEWHERE AT THE SURFACE A MODERATE RIDGE IS NORTH OF 14N WEST 
OF 110W. THIS FEATURE IS FORECAST TO STRENGTHEN SLIGHTLY THROUGH 
48 HOURS. NORTHEAST TO EAST TRADE WINDS OF 20 KT FROM ABOUT 10N 
TO 20N WEST OF 125W ARE FORECAST TO INCREASE SLIGHTLY THROUGH 48 
HOURS.

THE REMAINDER OF THE SURFACE IS ANALYZED AS A BROAD TROUGH 
INCLUDING THE ITCZ AND THE LOW MENTIONED ABOVE.
 
A DEEP LAYER TROUGH IS NORTHWEST OF A LINE THROUGH 32N114W TO 
18N140W. THE AREA IS CLOUD FREE IN THE MIDDLE AND UPPER LEVELS 
WITH MOSTLY OVERCAST STRATOCUMULUS IN THE LOWER LEVELS. THE 
TROUGH IS EXPECTED TO REMAIN MOSTLY UNCHANGED THROUGH MIDDAY 
SUNDAY THEN GET PICKED UP IN THE WESTERLIES AND MOVE OVER THE 
UNITED STATES AND NORTHERN MEXICO.

A BROAD WEAK DEEP LAYER TROUGH IS ASSOCIATED WITH THE LOW IN THE 
GULF OF HONDURAS AND THE ONE SOUTH OF THE GULF OF TEHUANTEPEC 
REGION. THE FEATURE IS FORECAST TO WEAKEN VERY SLOWLY THROUGH 48 
HOURS AND REMAIN NEARLY STATIONARY.

LONG PERIOD SOUTH SWELL IS CROSSING THE EQUATOR INTO SOUTH 
CENTRAL WATERS WITH SEAS 8 TO 10 FT N THE REGION S OF 10S 
BETWEEN 92W AND 125W BY TONIGHT AND CONTINUING THROUGH MONDAY.

$$
LL