000
AXPZ20 KNHC 170344
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN AUG 17 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 
0315 UTC.

...SPECIAL FEATURE...
TROPICAL DEPRESSION ISELLE 18.6N 112.7W MOVING NW AT 3 KNOTS AT 
0300 UTC.  MAXIMUM SUSTAINED WIND 30 TO 40 KT.  SCATTERED DEEP 
MODERATE CONVECTION PREVIOUSLY ASSOCIATED WITH ISELLE HAS 
DECOUPLED FROM CIRCULATION CENTER WEAKENING IT SIGNIFICANTLY.
STRONGER SELY WIND SHEAR ALOFT AND COOL SEA SURFACE TEMPERATURE 
WERE JUST TOO MUCH FOR SYSTEM.  AT 0300 UTC NHC ISSUED ITS LAST 
ADVISORY UNLESS REGENERATION OCCURS.  LAST NHC FORECAST/ADVISORY 
UNDER AWIPS/WMO HEADER MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
NONE.

...ITCZ...
ITCZ AXIS ALONG 09N80W TO 08N87W TO 11N98W TO 10N106W TO 11N114W 
10N123W TO 10N130W 09N137W TO 09N140W.  SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WITHIN 60 NM S OF AXIS E OF 91W.  
SCATTERED MODERATE CONVECTION WITHIN 60 NM N AND 120 NM S OF 
AXIS FROM 114W-133W.

...DISCUSSION...
UPPER TROUGH FROM 32N131W TO 20N124W BEING SQUEEZED NE BY BROAD 
REBUILDING ANTICYCLONE CENTERED AT 27N106W AND SMALLER BUT VERY 
DRY ANTICYCLONE PUSHING FROM THE W CENTERED AT 21N133W.  BROAD 
GYRE ADVECTS PLENTY OF MOISTURE ALONG ITS SRN PERIPHERY E OF 
120W WHILE SMALL GYRE MAINTAINS DRYNESS N OF 17N E OF 120, THAT 
ALLOWS ITCZ TO PUSH MOISTURE S OF 12N ALL THE WAY TO 136W...BUT 
LACK OF MECHANICAL LIFT INHIBITS DEEP CONVECTION.  ONLY CLUSTERS 
OF CONVECTION ARE CLOSE TO...BUT NOR COUPLED ANY LONGER...WITH 
T.D. ISELLE.  MODERATE ELY SHEAR PERSISTS S OF UPPER RIDGES 
ADDING TO THE HOSTILE UPPER ENVIRONMENT FOR DEEP CONVECTION 
ALONG ITCZ. 

$$
WALLY BARNES