000
AXPZ20 KNHC 050322
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0245 UTC.

...SPECIAL FEATURES...
HURRICANE EUGENE AT 17.4N 121.2W AT 05/0300 UTC MOVING W-NW OR 
285 DEGREES AT 11 KT WITH ESTIMATED CENTRAL PRES OF 981 MB. 
MAXIMUM SUSTAINED WINDS ARE 75 KT WITH GUSTS TO 90 KT. EUGENE IS 
NOW A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON HURRICANE 
WIND SCALE. ADDITIONAL WEAKENING IS FORECAST DURING THE NEXT 48 
HOURS...AND EUGENE SHOULD BECOME A TROPICAL STORM BY FRIDAY 
MORNING AS IT MOVES OVER WATERS COLDER THAN 24C AND INTO A DRIER 
AND MORE STABLE ENVIRONMENT. SCATTERED MODERATE TO ISOLATED 
STRONG CONVECTION IS FROM 15N TO 18N BETWEEN 118W AND 122W. 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...
MONSOON TROUGH AXIS EXTENDS FROM 08N77W TO 08N85W TO 12N92W TO 
14N103W THEN CONTINUES FROM 13N124W TO 10N130W TO 10N137W. THE 
ITCZ AXIS CONTINUES FROM 10N137W TO BEYOND 09N140W. SCATTERED 
MODERATE CONVECTION LIES OVER COSTA RICA FROM 08N TO 10N BETWEEN 
83W AND 85W. SIMILAR CONVECTION IS FROM 09N TO 11N BETWEEN 133W 
AND 135W.

...DISCUSSION...
A 1032 MB HIGH PRES CENTERED NW OF THE AREA NEAR 37N151W EXTENDS 
A RIDGE OVER THE NORTHERN FORECAST WATERS MAINLY N OF 20N AND W 
OF 120W. PRES GRADIENT BETWEEN THE RIDGE TO THE N AND HURRICANE 
EUGENE TO THE S HAS INCREASED ENOUGH TO PRODUCE FRESH N TO NE 
WINDS OVER A LARGE AREA N OF 18N W OF 120W. AN 1843 UTC ASCAT 
PASS CONFIRMED THESE CONDITIONS. IN ADDITION...FRESH TRADE WINDS 
ARE BLOWING ON THE SOUTHERN PERIPHERY OF THE RIDGE W OF 130W.

A SURFACE TROUGH IS ALONG THE COAST OF MEXICO FROM 18N103W TO 
14N103W. AN 1658 UTC ASCAT CONFIRMED A TROUGH OVER THE AREA 
VERSUS A LOW CENTER. SCATTERED MODERATE CONVECTION IS FROM 14N 
TO 19N BETWEEN 101W AND 107W. 

CROSS-EQUATORIAL SWELL IS BUILDING SEAS TO ABOVE 9 FT IN THE S 
CENTRAL WATERS. SW SWELL WILL CONTINUE TO KEEP WAVE HEIGHTS IN 
THE 8 TO 10 FT RANGE THROUGH THE NEXT COUPLE OF DAYS.

NORTHERLY WINDS WILL INCREASE TO 20 KT N OF 27N WITHIN 180 NM OF 
THE W COAST OF THE BAJA CALIFORNIA PENINSULA IN 24 HOURS AS THE 
PRES GRADIENT IN THE AREA TIGHTENS.

OTHERWISE...AN UPPER ANTICYCLONE IS CENTER OVER CENTRAL BAJA 
CALIFORNIA AT 28113W EXTENDING A RIDGE SW TO 23N125W. EUGENE IS 
MOVING W-NW AROUND THE SOUTHERN PERIPHERY OF THIS RIDGE.

$$
FORMOSA/LEWITSKY