000 AXPZ20 KNHC 040910 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC THU AUG 04 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0745 UTC. ...SPECIAL FEATURES... HURRICANE EUGENE AT 16.7N 117.8W AT 04/0900 UTC MOVING W-NW OR 285 DEGREES AT 12 KT WITH CENTRAL PRES 950 MB. MAXIMUM SUSTAINED WINDS ARE 110 KT WITH GUSTS TO 135 KT. SCATTERED MODERATE CONVECTION LIES WITHIN 120 NM OF THE CENTER EXCEPT 270 NM IN THE S QUADRANT. EUGENE CURRENTLY LIES IN A LOW-SHEAR ENVIRONMENT BUT IS BEGINNING TO MOVE INTO COOLER WATERS. A GRADUALLY WEAKENING TREND IS FORECAST AS EUGENE CONTINUES W-NW OVER THE NEXT FEW DAYS. 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 10N86W TO 15N96W TO 1006 MB LOW PRES NEAR 15N100W THEN CONTINUES FROM 12N121W TO 09N135W. ITCZ AXIS EXTENDS FROM 09N135W TO 08N140W. SCATTERED MODERATE CONVECTION LIES WITHIN 90 NM W SEMICIRCLE OF LOW PRES NEAR 15N100W. ...DISCUSSION... THE 1028 MB SUBTROPICAL HIGH IS CENTERED NW OF THE AREA NEAR 35N151W. IT HAS BEEN DISPLACED WESTWARD THE LAST FEW DAYS BY MEAN TROUGHING OFF THE W COAST OF THE UNITED STATES. AS A RESULT...THE FRESH TRADE WINDS HAVE BEEN PRIMARILY FOUND W OF 130W. HOWEVER...THE PRES GRADIENT BETWEEN THE SUBTROPICAL RIDGE TO THE N AND HURRICANE EUGENE TO THE S HAS INCREASED ENOUGH OVER THE LAST FEW HOURS FOR FRESH N TO NE WINDS TO EXPAND OVER MUCH OF THE AREA N OF 27N. THE 0430 UTC AND 0610 UTC ASCAT PASSES CONFIRMED THESE CONDITIONS. A MEAN UPPER RIDGE AXIS EXTENDS FROM 17N140W THROUGH AN ANTICYCLONE NEAR CENTRAL BAJA CALIFORNIA AT 26N114W TO EL PASO TEXAS. THIS RIDGE AXIS WILL SLOWLY SHIFT NORTHWARD OVER THE NEXT FEW DAYS AND WILL HELP STEER HURRICANE EUGENE W-NW INTO COOLER WATERS. ANOTHER RIDGE AXIS EXTENDS S FROM THE ANTICYCLONE AND PARALLELS THE COAST OF MEXICO TO 16N105W. THE DIFFLUENCE ALOFT ASSOCIATED WITH THIS RIDGE AXIS IS ENHANCING THE SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WITHIN 60 NM OF THE MEXICAN COAST FROM 20N TO 24N AND THE SCATTERED MODERATE CONVECTION IN THE GULF OF CALIFORNIA FROM 25N TO 28N. THE 0426 UTC ASCAT PASS CAUGHT THE EASTERN SIDE OF HURRICANE EUGENE. THE FRESH TO STRONG WINDS EXTEND AS FAR AS 240 NM NE QUADRANT AND 450 NM SE QUADRANT ACCORDING TO THE PASS. THE 0604 UTC ASCAT PASS CONTINUES TO SHOW FRESH TO STRONG S TO SW WINDS FEEDING INTO EUGENE AND THE MONSOON TROUGH TO ITS SW FROM N OF 04N BETWEEN 113W AND 128W. A JASON 1 PASS FROM 0402 UTC CAME WITHIN 390 NM OF THE CENTER AND SHOWED A LARGE AREA OF SEAS 12 FT OR GREATER IN THE EASTERN SEMICIRCLE. THE 12 FT SEA RADII WERE EXPANDED IN THE E SEMICIRLCE BASED ON THIS PASS AND THE WAVE FORECAST GUIDANCE. CROSS-EQUATORIAL SWELL HAS BROUGHT SEAS ABOVE TO 9 FT IN S CENTRAL WATERS. SW SWELL WILL CONTINUE TO KEEP WAVE HEIGHTS ABOVE ADVISORY CRITERIA HERE THROUGH THE PERIOD AND THE SW MONSOON FLOW OVER S CENTRAL WATERS IS EXPECTED TO INCREASE TO FRESH BY FRI MORNING. A 1006 MB LOW PRES SYSTEM SW OF THE ACAPULCO MEXICO NEAR 15N100W HAS SCATTERED MODERATE CONVECTION WITHIN 90 NM OF ITS W SEMICIRCLE. THE 0426 UTC ASCAT PASS SHOWED 25 KT WINDS WITHIN 45 NM OF THE LOW. THE LOW CURRENTLY LIES UNDER ABOUT 20-25 KT OF EASTERLY SHEAR. THE CURRENT FORECAST CALLS FOR THE LOW TO TRACK W-NW WITH LITTLE CHANGE IN INTENSITY OVER THE NEXT FEW DAYS. HOWEVER...CONFIDENCE IN THIS FORECAST IS SOMEWHAT LOW. $$ SCHAUER