000
AXPZ20 KNHC 311004
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI AUG 31 2012

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...SPECIAL FEATURE...
HURRICANE ILEANA AT 21.8N 114.8W AT 31/0900 UTC MOVING NW OR 320 
DEG AT 6 KT WITH MINIMUM CENTRAL PRES 985 MB.  MAXIMUM SUSTAINED 
WIND SPEED 65 WITH GUSTS TO 80 KT.  SCATTERED MODERATE ISOLATED 
STRONG CONVECTION WITHIN 90 NM OF CENTER.  CYCLONE APPROACHING 
COOL SURFACE TEMPERATURES AND WEAKENING.  SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC 
FOR MORE DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...MONSOON 
TROUGH AXIS FROM 12N86W TO 1011 MB LOW PRES 11N91W TO  08N98W TO 
08N108W...THEN RESUMES 14N115W TO 10N125W TO BEYOND 10N140W.  
SCATTERED MODERATE ISOLATED STRONG BETWEEN AXIS AND 05N E OF 
100W.

...DISCUSSION...
UPPER LEVEL TROUGH EXTEND FROM 32N128W TO 18N122W COMBINES WITH 
BROAD ANTICYCLONE AT 17N130W TO KEEP DRY AIR MASS N OF 12N W OF 
120W.  SECOND ANTICYCLONE AT 27N110W HELPS OUTFLOW OVER N HALF 
OF ILEANA AND ADVECTS ABUNDANT TROPICAL MOISTURE INTO E PAC E OF 
120W.  NEVERTHELESS ITS MODERATE TO STRONG NE FLOW ALSO ACTS 
AGAINST DEVELOPMENT OF DEEP CONVECTION.  ONLY MODERATE DIVERGENT 
FLOW OFFSHORE GUATEMALA IS ABLE TO ENHANCE SCATTERED CONVECTION 
ASSOCIATED WITH 1011 MB SURFACE LOW PRES AT 11N91W.  

ELSEWHERE AT THE LOW LEVELS...LONG PERIOD CROSS EQUATORIAL SW 
SWELL UP TO 12 FT PROPAGATE N TO 07N W OF 80W.

$$
WALLY BARNES