000
AXPZ20 KNHC 302203
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU OCT 30 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 2045 UTC.

...ITCZ...
THE ITCZ AXIS CAN BE FOUND ALONG 08N78W TO 07N90W TO 06N100W TO 
11N120W TO 07N140W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION LIES WITHIN 90 NM N AND 150 NM S OF AXIS FROM 79W TO 
85W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 60 NM N 
AND 90 NM S OF AXIS FROM 100W TO 138W.  

...DISCUSSION...
THE HIGHLY AMPLIFIED MID LATITUDE UPPER PATTERN DIPPING 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...DIVING SE INTO THE BACKSIDE OF THE TROUGH TONIGHT 
AND HELPING TO PUSH THE BROAD TROUGH EASTWARD OVER THE RIDGE. 
THE TROUGH CURRENTLY IN PLACE OVER NW WATERS IS FORECAST TO 
DISSIPATE OVER THE NEXT TWO DAYS...WITH A SECOND COLD FRONT 
ASSOCIATED WITH THE ENERGY S OF THE ALEUTIANS MOVING INTO NW 
WATERS OVER THE WEEKEND.  NW SWELL WILL DOMINATE NW WATERS 
THROUGH THE DISCUSSION PERIOD.

THE STRONG SURFACE PRESSURE GRADIENT OVER CENTRAL AMERICA WILL 
CONTINUE TO PRODUCE GALE FORCE WINDS THROUGH THE GULF OF 
TEHUANTEPEC FOR AT LEAST THE NEXT TWO DAYS.  HOWEVER...THE 
STRONG WINDS CURRENTLY THROUGH THE GULFS OF PAPAGAYO AND FONSECA 
ARE FORECAST TO WEAKEN TO 20 KT OR BELOW OVER THE WEEKEND.  

A TROUGH ALONG 93W CURRENTLY LIES UNDER A REGION OF 30 KT UPPER 
LEVEL EASTERLY FLOW.  THIS WIND SHEAR IS LIKELY LIMITING 
CONVECTION.  CURRENTLY...SCATTERED MODERATE CONVECTION CAN BE 
FOUND WITHIN 300 NM W AND 150 NM E OF TROUGH ALONG 93W FROM 05N 
TO 09N.  THE SYSTEM WAS LIKELY SPURRED BY THE ADDED ATMOSPHERIC 
VORTICITY FROM THE LOW TO MID LEVEL JET THROUGH THE GULF OF 
PAPAGAYO.

TWO MORE SURFACE TROUGHS...ONE ALONG 118W AND ANOTHER ALONG 
133W...LIE THE THE REAR RIGHT QUADRANTS OF TWO UPPER LEVEL 
JETS...ONE IN ASSOCIATION WITH THE BROAD TROUGH OVER NW WATERS 
AND THE OTHER ASSOCIATED WITH THE WEAKENING UPPER TROUGH OFF THE 
BAJA.  THE TROUGH ALONG 118W IS CURRENTLY SUPPORTING SCATTERED 
MODERATE WITH ISOLATED STRONG WITHIN 60 NM W AND 270 NM E OF 
TROUGH BETWEEN 08N AND 14N WHILE THE CONVECTION ASSOCIATED WITH 
THE TROUGH ALONG 135W IS MORE SCATTERED.  LOOK FOR THE 
PROGRESSIVE UPPER LEVEL PATTERN TO MAKE CONVECTION LESS LIKELY 
WITH THESE SYSTEMS OVER THE NEXT DAY OR TWO.

$$
SCHAUER CLARK