000
AXPZ20 KNHC 231003
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU OCT 23 2008

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 08N84W TO 07N91W TO 11N104W TO 
10N120W TO 09N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND 
WITHIN 120 NM N AND 60 NM S OF AXIS BETWEEN 115W AND 127W. 
 
...DISCUSSION...

A HIGHLY AMPLIFIED MID LEVEL PATTERN HAS TAKEN HOLD N OF 20N... 
WITH TROUGHING BUILDING OVER NW WATERS AND MUCH OF NORTHERN 
MEXICO WHILE RIDGING HOLDS STRONG IN BETWEEN ALONG 120W TO 
125W.  A COLD FRONT ASSOCIATED WITH THE TROUGHING OVER MEXICO 
HAS PUSHED S OF THE RIO GRANDE AND WILL CONTINUE TO MOVE 
SOUTHEASTWARD THROUGH MUCH OF NORTHERN MEXICO AND THE WESTERN 
GULF OF MEXICO OVER TODAY.  STRONG N WINDS WILL SPILL THROUGH 
THE CHIVELA PASS AND INDUCE A GALE EVENT LATE TONIGHT/EARLY 
TOMORROW.  IT IS EXPECTED TO BE RELATIVELY SHORT LIVED AS THE 
COLD FRONT AND ITS ATTENDANT HIGH WILL BE PROGRESSIVE...MOVING 
EASTWARD AND WEAKENING THE PRESSURE GRADIENT HERE BY LATE FRI.  
MEANWHILE...STRONG WINDS HAVE ALREADY BEEN INDUCED ACROSS THE 
NORTHERN GULF OF CALIFORNIA WHERE AMBIENT LOW PRESSURE IS IN 
CONTRAST TO THE HIGH PRESSURE PUSHING SOUTHWARD BEHIND THE COLD 
FRONT.  WINDS HERE ARE EXPECTED TO STAY JUST BELOW GALE FORCE 
THIS MORNING AND SHOULD WANE THROUGH THE DAY AS THE SURFACE 
RIDGE SHIFTS EASTWARD.

THE SURFACE LOW PRESSURE SYSTEM CURRENTLY NEAR 12N105W IS 
SUPPORTING DEEP CONVECTION WITHIN 120 NM IN ITS N QUADRANT.  THE 
LOW WILL HAVE A SHORT WINDOW OF TIME TO BECOME BETTER ORGANIZED 
BEFORE ENCOUNTERING STRONG SOUTHWESTERLY SHEAR ON THE LEADING 
EDGE OF THE APPROACHING UPPER TROUGH.  THE CURRENT FORECAST 
CALLS FOR THE SYSTEM TO STRENGTHEN SLIGHTLY AND CONTINUE ON A NW 
PATH THROUGH SAT MORNING BEFORE WEAKENING TO A TROUGH AT THE 
SURFACE AND TAKING ON A MORE NORTHERLY TURN OVER THE WEEKEND. 

THE DEEP LAYERED LOW APPROACHING NW WATERS IS EXPECT TO HOLD 
STRONG ALOFT...BUT WEAKEN OVER THE NEXT TWO DAYS AT THE SURFACE 
AS HIGH PRESSURE REBUILDS.  THE COLD FRONT ASSOCIATED WITH THIS 
SYSTEM IS CURRENTLY APPROACHING THE THE FORECAST AREA...BUT THE 
LOW LEVEL BOUNDARY IS EXPECTED TO DISSIPATE TOMORROW MORNING.  A 
QUIKSCAT PASS AT 0356 UTC SHOWED THE 20 KT WINDS WERE STILL WEST 
OF 140W AND WITH THE SYSTEM EXPECTED TO WEAKEN QUICKLY AT THE 
SURFACE...THE MAIN THREAT OVER FORECAST WATERS WILL BE THE NW 
SWELL INDUCED BY THE SYSTEM WHICH WILL APPROACH 12 FT. 

$$
SCHAUER CLARK