000
AXPZ20 KNHC 211524
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE OCT 21 2008

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1430 UTC.

...ITCZ...

THE ITCZ AXIS LIES ALONG A LINE FROM 08N83W TO 12N97W TO 11N111W 
TO 09N121W TO 08N140W. CLUSTERS OF SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION ARE FROM 09N TO 13N BETWEEN 95W AND 
108W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 180 
NM N OF AXIS FROM 110W TO 120W AND WITHIN 180 NM S OF THE AXIS 
FROM 110W TO 125W.

...DISCUSSION...

A WEAK 1011 MB SURFACE LOW IS EMBEDDED WITHIN THE ITCZ NEAR 
11N104W. BROAD UPPER RIDGE EXTENDS FROM NW NICARAGUA W TO 
11N110W PROVIDING UPPER DIFFLUENCE TO ENHANCE THE CONVECTION 
WITHIN THE ITCZ MOSTLY E OF THE SURFACE LOW. BROAD UPPER 
ANTICYCLONE IS CENTERED JUST N OF THE ITCZ NEAR 14N136W COVERING 
THE AREA S OF 21N W OF 120W. AN UPPER TROUGH IS DIGGING S OVER 
NW MEXICO AND THE BAJA PENINSULA N OF 26N E OF 120W WITH A CUT 
OFF MID LEVEL LOW TO THE W NEAR 25N35W. 

THE CUT OFF MID LEVEL LOW WILL SHIFT EASTWARD OVER THE NEXT FEW 
DAYS AS A STRONG DEEP LAYERED TROUGH MOVES INTO THE NW SECTION 
LAT WED/EARLY THU.  THE UPPER TROUGH OVER NW MEXICO WILL ALSO 
SHIFT EASTWARD INTO THE CENTRAL US AND GULF OF MEXICO DURING THE 
SAME TIME FRAME.  

A BROAD SURFACE RIDGE DOMINATES THE REGION N OF 20N W OF 120W 
AND WILL REMAIN UNTIL A COLD FRONT BEGINS MOVING INTO THE REGION 
DURING THE DAY THU. WHILE WINDS IN THE GULF OF TEHUANTEPEC 
REMAIN STRONG THEY ARE BELOW GALE FORCE. LARGE SWELLS ARE MOVING 
N ACROSS THE EQUATOR COVERING MOST OF THE S PORTION OF THE 
AREA.  

$$
WALLACE