000
AXPZ20 KNHC 282144
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURE...

TROPICAL STORM ILEANA NEAR 16.3N 110.7W AT 28/2100 UTC MOVING 
WNW OR 295 DEG AT 9 KT. MAXIMUM SUSTAINED WINDS 45 KT GUSTS 55 
KT. ESTIMATED MINIMUM CENTRAL PRESSURE 999 MB. ILEANA IS 
EXPECTED TO MOVE W-NW THEN NW WITH A SLIGHT DECREASE IN FORWARD 
SPEED OVER THE NEXT COUPLE OF DAYS. THE NHC INTENSITY FORECAST 
CALLS FOR ILEANA TO BECOME A HURRICANE IN A DAY OR SO AND THEN 
WEAKEN GRADUALLY AS IT ENCOUNTERS COOLER WATERS IN ABUT THREE 
DAYS. NUMEROUS MODERATE TO STRONG CONVECTION IS WITHIN 75 NM NW 
SEMICIRCLE OF ILEANA. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION IS NOTED ELSEWHERE FROM 13N TO 18N BETWEEN 105W AND 
115W. 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 10N99W THEN RESUMES OF 
ILEANA NEAR 14N115W TO 1011 MB LOW PRES LOCATED NEAR 11N136W TO 
08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FROM 
05N TO 08N E OF 90W AND FROM 10N TO 16N BETWEEN 96W AND 105W. 
SCATTERED MODERATE IS FROM 10N TO 13N BETWEEN 110W AND 117W AND 
WITHIN 90 NM W QUADRANT OF LOW PRES NEAR 11N136W.

...DISCUSSION...

1030 HIGH PRES LOCATED WELL NW OF THE FORECAST AREA EXTENDS A 
RIDGE SE ACROSS THE N WATERS TO NEAR 22N115W. LIGHT TO MODERATE 
WINDS ARE NOTED UNDER THE INFLUENCE OF THIS SYSTEM MAINLY N OF 
20N W OF 120W. A SMALL AREA OF ENHANCED N-NE WINDS IS PRESENT ON 
THE SOUTHERN PERIPHERY OF THE RIDGE...COVERING ROUGHLY THE 
REGION FROM 12N TO 16N W OF 130W. 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 FROM THIS MORNING AND THE MOST RECENT OSCAT 
PASS CONFIRMED THE PRESENCE OF THESE WIND SPEEDS.

SCATTEROMETER DATA SHOWS A LARGE AREA OF FRESH TO STRONG SW 
WINDS S OF THE MONSOON TROUGH BETWEEN 105W AND 120W ASSOCIATED 
WITH INTENSIFYING T.S. ILEANA. AN ACTIVE MONSOON TROUGH IS NOTED 
ACROSS THE FORECAST AREA.  

A WEAK 1011 MB LOW PRES...EMBEDDED IN THE MONSOON TROUGH...IS 
NEAR 11N136W WITH A TROUGH EXTENDING NE TO NEAR 14N133W. THE 
1912 UTC ASCAT PASS SHOWS PART OF THE CYCLONIC CIRCULATION 
ASSOCIATED WITH THIS SYSTEM FORECAST TO MOVE W OF AREA BY WED. A 
SMALL AREA OF MODERATE CONVECTION IS W OF THE LOW CENTER.

CROSS-EQUATORIAL SW SWELLS WITH IMPRESSIVE 20-22 SECOND PERIOD  
ARE CURRENTLY SPREADING ACROSS THE SOUTH WATERS W OF 110W. THIS 
SWELL EVENT WILL RAISE SEAS TO 9 FT MAINLY S OF 06N BETWEEN 110W 
AND 135W BY LATE WED.

$$
GR