000
AXPZ20 KNHC 051528
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI AUG 05 2011

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 FEATURES...

EUGENE WAS DOWNGRADED TO A TROPICAL STORM AT 05/1500 UTC. AT 
THIS TIME...IT IS CENTERED NEAR 17.9N 123.3W MOVING W-NW OR 285 
DEGREES AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 996 MB. 
MAXIMUM SUSTAINED WINDS HAVE DECREASED TO 55 KT WITH GUSTS TO 65 
KT. ADDITIONAL WEAKENING IS FORECAST AS THE CYCLONE TRAVERSES 
COLDER WATER AND AN INCREASINGLY MORE STABLE ENVIRONMENT. EUGENE 
WILL LIKELY BECOME A REMNANT LOW BY SUNDAY. SEE LATEST NHC 
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS TCPEP5/WTPZ35 KNHC AND 
FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS TCMEP5/WTPZ25 FOR 
MORE DETAILS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH IS ALONG 10N86W TO 08N96W TO 14N104W THEN 
RESUMES NEAR 15N125W TO 11N131W. THE INTERTROPICAL CONVERGENCE 
ZONE AXIS EXTENDS FROM 11N131W TO 09N140W. SCATTERED MODERATE 
CONVECTION IS NOTED FROM 06N TO 10N BETWEEN 92W AND 100W...AND 
FROM 08N TO 10N BETWEEN 131W AND 138W.

...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 27N115W WITH AN 
UPPER RIDGE EXTENDING SW TO A COL NEAR 22N130W. TROPICAL CYCLONE 
EUGENE CONTINUES TO MOVE WNW AROUND THE SOUTHERN PERIPHERY OF 
THIS RIDGE. AN UPPER LEVEL TROUGH IS CLIPPING THE FAR NW CORNER 
OF THE AREA AND WILL REMAIN BLOCKED BY THE ANTICYCLONE DURING 
THE NEXT 24-48 HOURS. VERY DRY AIR UNDER MODERATE TO STRONG 
SUBSIDENCE IS NOTED BY WATER VAPOR SATELLITE IMAGERY N OF 15N W 
OF 130W AN N OF 23N W OF THE BAJA CALIFORNIA PENINSULA. 
OTHERWISE...NE-E UPPER LEVEL WINDS DOMINATE THE REMAINDER OF THE 
FORECAST AREA.

AT THE SURFACE...1032 MB HIGH PRES CENTERED NW OF THE FORECAST 
REGION NEAR 39N149W EXTENDS A RIDGE OVER THE NORTH WATERS N OF 
22N. THE PRES GRADIENT BETWEEN THE RIDGE AND EUGENE IS RESULTING 
IN FRESH NE WINDS N OF 19N W OF 127W WHICH WAS EVIDENT IN 0550 
UTC ASCAT PASS. IN ADDITION...A SMALL AREA OF 20 KT TRADE WINDS 
ARE OCCURRING FROM 10N TO 12N W OF 136W.

THE 0542 UTC ASCAT OVERPASS EUGENE SHOWING A MAXIMUM INTENSITY 
OF AROUND 50 TO 55 KT. THE FRESH TO STRONG WINDS EXTEND AS FAR 
AS 240 NM N SEMICIRCLE AND 180 NM S SEMICIRCLE. FRESH TO STRONG 
S TO SW WINDS CONTINUE TO FEED INTO EUGENE FROM N OF 10N BETWEEN 
118W AND 123W ACCORDING TO THE SAME SCATTEROMETER DATA. 

A WEAK AREA OF LOW PRESSURE CENTERED ABOUT 150 MILES SOUTH OF 
MANZANILLO MEXICO CONTINUES TO PRODUCE DISORGANIZED SHOWER AND 
THUNDERSTORM ACTIVITY OFFSHORE OF THE SOUTHWESTERN COAST OF 
MEXICO PARTICULARLY FROM 15N TO 20N BETWEEN 104W AND 107W. 
ENVIRONMENTAL CONDITIONS ARE NOT CONDUCIVE FOR DEVELOPMENT...AND 
THIS SYSTEM HAS A LOW CHANCE OF BECOMING A TROPICAL CYCLONE 
DURING THE NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD NEAR 10 
MPH.

CROSS-EQUATORIAL SOUTHERLY SWELL IS BUILDING SEAS TO 10 FT S OF 
09N/10N W OF 100W. THIS SWELL OF 8-10 FT WILL GRADUALLY DECAY 
AND BECOME CONFINED TO W OF 110W IN 48 HOURS.

NORTHERLY WINDS WILL INCREASE TO 20 KT N OF 28N WITHIN 120 NM OF 
THE W COAST OF THE BAJA CALIFORNIA PENINSULA IN ABOUT 12 HOURS 
AS THE PRES GRADIENT IN THE AREA TIGHTENS. WINDS ARE FORECAST TO 
BE BELOW 20 KT BY 36 HOURS.

$$
GR