000 AXPZ20 KNHC 231015 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI SEP 23 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 0930 UTC. ...SPECIAL FEATURE... HURRICANE HILARY WAS NEAR 16.0N 101.9W AT 0900 UTC MOVING W OR 280 DEG AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 944 MB. MAXIMUM SUSTAINED WINDS HAVE CONTINUED TO INCREASE OVERNIGHT TO 125 KT WITH GUSTS TO 150 KT MAKING HILARY A CATEGORY FOUR HURRICANE ON THE SAFFIR-SIMPSON SCALE. SATELLITE PRESENTATION HAS BECOME QUITE IMPRESSIVE OVERNIGHT WITH A SMALL WELL DEFINED 10 NM EYE AND NUMEROUS STRONG CONVECTION WITHIN 100 NM OF THE CENTER IN ALL DIRECTIONS. HILARY IS UNDER A BROAD UPPER LEVEL ANTICYCLONE AND OVER VERY WARM SEA SURFACE TEMPERATURES...BOTH FACTORS CONDUCIVE TO MAINTAINING ITS CURRENT INTENSITY. HILARY IS THE FOURTH MAJOR HURRICANE OF 2011 EAST PACIFIC HURRICANE SEASON. HILARY IS EXPECTED TO MAINTAIN A WNW MOTION FOR THE NEXT FEW DAYS WITHIN MODEST FLUCTUATIONS IN INTENSITY DURING THE NEXT 24 HOURS BEFORE IT BEGINS A TREND OF SLOW WEAKENING OVER THE FOLLOWING SEVERAL DAYS. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM 08N82W TO 07N89W AND THEN FROM 16N103W TO 16N110W TO 12N120W TO 12N127W TO 09N133W. SCATTERED MODERATE ISOLATED STRONG WITHIN 90 NM EITHER SIDE OF A LINE FROM 13N103W TO 11N109W AND FROM 10N116W TO 08N121W...AND WITHIN 75 NM OF 17N BETWEEN 106W AND 109W. ...DISCUSSION... A NARROW UPPER LEVEL TROUGH EXTENDS FROM AN UPPER CYCLONE OFF THE SW COAST OF CALIFORNIA NEAR 32N122W TO A SECOND UPPER CYCLONE NEAR 23N140W. BROAD MID/UPPER LEVEL RIDGING COVERS THE REMAINDER OF THE AREA ANCHORED BY AN ELONGATED ANTICYCLONE EXTENDING FROM HURRICANE HILARY E-E TO THE YUCATAN PENINSULA AND EXTENDING W-SW TO 13N136W. WATER VAPOR IMAGERY SHOWS MODERATE TO STRONG SUBSIDENCE OVER THE AREA N OF 20N...WHILE CONVECTION IS DEEP AND QUITE ACTIVE WITHIN 360 NM SW THROUGH NW OF HILARY AND S OF THE MONSOON TROUGH. AT THE SURFACE...A WEAK HIGH PRESSURE RIDGE EXTENDS FROM A 1021 MB HIGH NEAR 34N132W SE TO BAJA CALIFORNIA NEAR 27N113W. LIGHT TO MODERATE TRADEWINDS CONTINUE N OF THE MONSOON TROUGH AND W OF 120W...WITH A FEW ZONES OF 15-20 KT S OF 20N AND W OF 123W. S TO SW MONSOONAL FLOW TO 20 KT IS ALSO FOUND S OF THE MONSOON TROUGH FROM 02N TO 08N BETWEEN 112W AND 126W. W AND NW OF HILARY...NW SWELL DOMINATES MARINE CONDITIONS PRODUCING SEAS OF 6 TO 9 FT THAT WILL DIMINISH SLIGHTLY THROUGH SAT. SOUTHERN HEMI SW SWELL DOMINATES THE REMAINDER OF THE AREA THIS MORNING YIELDING SEAS GENERALLY 5 TO 7 FT. THESE TWO SWELLS ARE FORECAST TO MERGE S OF 10N DURING THE NEXT FEW DAYS TO RAISE SEA HEIGHTS TO 6 TO 9 FT. SE SWELL FROM HURRICANE HILARY WILL GRADUALLY INVADE THE GULF OF CALIFORNIA THIS WEEKEND. $$ STRIPLING