000
AXPZ20 KNHC 310330
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI OCT 31 2008

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0230 UTC.

...ITCZ...
THE ITCZ CAN BE FOUND ALONG THE LINE FROM 08N78W TO 07N82W TO 
08N90W TO 07N106W TO 11N127W TO 08N140W. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION LIES WITHIN 90 NM OF THE AXIS FROM 
80W TO 98W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 60 
NM N AND 120 NM S OF THE AXIS W OF 132W.  

...DISCUSSION...
THE HIGHLY AMPLIFIED MID LATITUDE UPPER PATTERN ENCROACHING INTO 
THE NORTHERN PORTION OF THE REGION WILL GRADUALLY BECOME MORE 
ZONAL STARTING SAT AS THE ANTICYCLONE OVER SOUTHERN MEXICO AND 
ADJACENT WATERS DRIFTS W...SHIFTING THE DEEP TROUGH CURRENTLY 
OVER NW WATERS NORTHWARD AS IT BEGINS AN EASTWARD PUSH SPURRED 
ON BY A BATCH OF MID TO UPPER LEVEL ENERGY CURRENTLY S OF THE 
ALEUTIANS.  THIS SYSTEM WILL DIVE SE INTO THE BACKSIDE OF THE 
BROAD NE PACIFIC TROUGH TONIGHT AND HELP PUSH THE BROAD TROUGH 
EASTWARD OVER THE RIDGE. THE DEEP LAYER TROUGH CURRENTLY IN 
PLACE OVER NW WATERS IS FORECAST TO DISSIPATE TODAY...WITH A 
SECOND COLD FRONT ASSOCIATED WITH THE ENERGY S OF THE ALEUTIANS 
MOVING INTO NW WATERS BY THE WEEKEND.  NW SWELL WILL DOMINATE NW 
WATERS THROUGH THE DISCUSSION PERIOD.

THE REAR RIGHT QUADRANT OF THE WEAK UPPER TROUGH EXTENDING FROM 
THE SOUTHERN BAJA TO NEAR 15N BETWEEN 110W AND 120W IS 
SUPPORTING SCATTERED MODERATE TO ISOLATED STRONG CONVECTION 
WITHIN 60 NM OF TROUGH ALONG 118W FROM 10N TO 16N.  ANOTHER 
SOUTHERLY UPPER JET...ASSOCIATED WITH THE DEEP LAYER TROUGH OVER 
NORTHWEST WATERS...IS HELPING TO ENHANCE CONVECTION ALONG THE 
ITCZ AND NEAR THE TROUGH ALONG 134W. LOOK FOR THE PROGRESSIVE 
UPPER LEVEL PATTERN TO MAKE CONVECTION LESS LIKELY WITH THESE 
SYSTEMS OVER THE NEXT DAY OR TWO.

THE STRONG SURFACE PRESSURE GRADIENT OVER CENTRAL AMERICA WILL 
CONTINUE TO PRODUCE GALE FORCE WINDS THROUGH THE GULF OF 
TEHUANTEPEC FOR A LEAST THE NEXT TWO DAYS.  QSCAT PASS AT 0032 
UTC SHOWS THAT THE WIND FIELD IS STARTING TO SHRINK...WITH THE 
GALE FORCE WINDS ONLY EXTENDING AS FAR S AS 14N.  THE QSCAT PASS 
ALSO REVEALED THAT THE WIND FIELD IS DIMINISHING NEAR THE GULFS 
OF PAPAGAYO AND FONSECA AS WELL. WINDS ARE EXPECTED TO DROP 
BELOW 20 KT AND SEAS BELOW 8 FT ON SUN.

A SURFACE TROUGH ALONG 93W. THE SYSTEM WAS LIKELY SPURRED BY THE 
ADDED ATMOSPHERIC VORTICITY FROM THE LOW TO MID LEVEL JET 
THROUGH THE GULF OF PAPAGAYO AND IT MAY BE FURTHER REINFORCED AS 
IT PASSES SOUTH OF THE GULF OF TEHUANTEPEC TODAY.

$$
SCHAUER CLARK