000
AXPZ20 KNHC 281541
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE AUG 28 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...SPECIAL FEATURE...

TROPICAL STORM ILEANA NEAR 16.0N 109.8W AT 28/1500 UTC MOVING 
WNW OR 290 DEG AT 8 KT. MAXIMUM SUSTAINED WINDS 45 KT GUSTS 55 
KT. ESTIMATED MINIMUM CENTRAL PRESSURE 999 MB. THE CLOUD PATTERN 
HAS BECOME A LITTLE BETTER ORGANIZED WITH DEEP CONVECTION IN A 
LARGE CURVED BAND TO THE WEST OF THE CENTER WHERE NUMEROUS 
MODERATE AND SCATTERED STRONG CONVECTION IS NOTED. SCATTERED  
MODERATE AND ISOLATED STRONG CONVECTION IS SEEN ELSEWHERE FROM 
12N TO 18N BETWEEN 106W AND 116W. ILEANA IS EXPECTED TO MOVE 
W-NW THEN NW WITH A SLIGHT DECREASE IN FORWARD SPEED OVER THE 
NEXT COUPLE OF DAYS. THE INTENSITY FORECAST CALL FOR ILEANA TO 
BECOME A HURRICANE BY LATE WED...REACHING A PEAK INTENSITY OF 
70 KT BY THU MORNING. ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR 
STRENGTHENING THROUGH FRI...THEN WEAKENING AS IT MOVES OVER 
COOLER WATER. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO 
HEADER MIATCMEP4/ WTPZ24 KNHC FOR MORE DETAILS. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH IS ALONG 08N78W TO 07N80W TO 11N100W THEN 
RESUMES NEAR 13N115W TO 10N133W. THE INTERTROPICAL CONVERGENCE 
ZONE AXIS EXTENDS FROM 09N138W TO 08N140W. SCATTERED MODERATE 
CONVECTION IS WITHIN 60 NM OF A LINE FROM 06N81W TO 08N86W... 
FROM 06N TO 08N BETWEEN 91W AND 94W...AND FROM 08N TO 15N 
BETWEEN 96W AND 99W. ISOLATED MODERATE CONVECTION IS FROM 07N TO 
11N BETWEEN 113W AND 122W.

...DISCUSSION...

SCATTEROMETER DATA SHOWS FRESH-STRONG SW WINDS S OF THE MONSOON 
TROUGH BETWEEN 102W AND 120W ASSOCIATED WITH INTENSIFYING T.S. 
ILEANA. A SMALL AREA OF ENHANCED N-NE WINDS IS PRESENT N OF THE 
TROUGH W OF 124W. AN ACTIVE MONSOON TROUGH IS THE DOMINANT 
SYNOPTIC FEATURE ACROSS THE REGION. 

WEAK HIGH PRES RIDGE NW OF THE DISCUSSION AREA IS SUPPORTING 
LIGHT TO MODERATE WINDS MAINLY N OF 20N W OF 120W. PRES GRADIENT 
BETWEEN THE RIDGE AND A THERMAL TROUGH IN THE GULF OF CALIFORNIA 
IS MAINTAINING N-NW WINDS OF 15 TO 20 KT N OF 23 E OF 120W. FEW 
SHIP OBSERVATIONS AND THE MOST RECENT OSCAT PASS CONFIRMED THE 
PRESENCE OF THESE WIND SPEEDS.

CROSS-EQUATORIAL SW SWELL WITH IMPRESSIVE 20-22 SECOND PERIOD  
WILL START TO AFFECT THE EQUATORIAL REGION BETWEEN 100W AND 135W 
THIS AFTERNOON...BUILDING SEAS TO 9 FT MAINLY S OF 06N BETWEEN 
110W AND 135W BY LATE WED.

$$
GR