000 AXPZ20 KNHC 241021 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SAT SEP 24 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 0915 UTC. ...SPECIAL FEATURE... HURRICANE HILARY WAS NEAR 17.1N 105.2W AT 0900 UTC MOVING WNW OR 290 DEG AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 946 MB. MAXIMUM SUSTAINED WINDS ARE 120 KT WITH GUSTS TO 145 KT MAKING HILARY A CATEGORY FOUR HURRICANE ON THE SAFFIR-SIMPSON SCALE. SATELLITE PRESENTATION CONTINUES RATHER IMPRESSIVE WITH A SMALL EYE OF ABOUT 10 NM EVIDENT THIS MORNING. HOWEVER CLOUD TOP TEMPERATURES HAVE WARMED SLIGHTLY AND SUGGEST A SLIGHT WEAKENING OF HILARY. HILARY HAS LIKELY ALREADY REACHED ITS PEAK INTENSITY AND IS EXPECTED TO MAINTAIN AT OR JUST BELOW ITS CURRENT INTENSITY FOR THE NEXT TWO TO THREE DAYS AS THE HURRICANE CONTINUES MOVING WNW OVER WARM WATERS AND UNDER LITTLE VERTICAL WIND SHEAR. NUMEROUS STRONG CONVECTION OCCURRING IN BANDS WERE WITHIN 90 NM N AND 45 NM S OF CENTER...WHILE SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION WAS OCCURRING WITHIN 250 NM NW AND 310 NM SW OF CENTER. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM EXTREME SW CARIBBEAN AND ENTERS EPAC WATERS NEAR 10.5N86W TO 06N96W WHERE IT TERMINATES...THEN RESUMES W OF HILARY NEAR 17N113W TO 11N127W TO 10N140W. SCATTERED MODERATE ISOLATED STRONG N OF 04N E OF 86W. SCATTERED MODERATE TO STRONG WITHIN 120 NM S OF AXIS BETWEEN 92W AND 96W...AND WITHIN 150 NM OF AXIS BETWEEN 115W AND 130W. ...DISCUSSION... A MIDDLE/UPPER LEVEL CYCLONE REMAINED OFF THE CALIFORNIA COAST NEAR 36N124W AND LIFTING N THIS MORNING...WITH A TROUGH AXIS EXTENDING SW TO A SECOND CYCLONIC CIRCULATION NEARLY STATIONARY ALONG 25N139W. A SOUTHWESTERLY JET SEGMENT PREVAILED TO THE SE OF THE TROUGH WITH CORE WINDS SPEEDS UP TO 60 KNOTS. THE CYCLONE OFF THE CALIFORNIA COAST IS FORECAST TO LIFT NE OVER THE NEXT COUPLE OF DAYS LEAVING A WEAK TROUGH TRAILING SW ACROSS THE AREA...AND THIS LINGERING TROUGH IS FORECAST TO BE FORCED EWD STARTING SUNDAY BY A LONG WAVE TROUGH MOVING ACROSS THE NE PACIFIC. A ASSOCIATED COLD FRONT WAS LOCATED JUST NW OF THE LOCAL AREA THIS MORNING AND MOVING SE...AND IS EXPECTED TO REACH NEAR 30N AND 140W LATE TONIGHT BEFORE WEAKENING AND BEGINNING TO DRIFT BACK TOWARDS THE NW SUNDAY. SW WINDS NEAR 20 KT WILL BE SEEN JUST AHEAD OF THE FRONT WITH SEAS BUILDING 8 TO 9 FT IN NW SWELL. SE OF THE TROUGH...UPPER LEVEL RIDGING PERSISTED AND WAS VENTING CONVECTION ASSOCIATED WITH HILARY AND S OF THE MONSOON TROUGH NICELY. ELSEWHERE AT THE SURFACE...A 1020 MB HIGH WAS CENTERED NEAR 27N130W WITH WEAK RIDGE AXIS EXTENDING SE TO SOUTHERN BAJA CALIFORNIA NEAR 25N112W. THE PRESSURE GRADIENT ALONG THE W COAST OF BAJA WAS PRODUCING MODERATE NWLY WINDS THIS MORNING BUT IS EXPECTED TO INCREASE TO 20 KT WITHIN 24 HOURS. A FEW WEAK PERTURBATIONS WERE EMBEDDED WITHIN THE MONSOON TROUGH ACROSS THE AREA AND WERE PRODUCING A SMALL AND NARROW ZONE OF NE TRADEWINDS TO 20 KT W OF 126W WHERE SEAS WERE NEAR 8 FT. LIGHT TO MODERATE S TO SW MONSOONAL FLOW PREVAILED S OF THE THROUGH THIS MORNING AND WERE PRODUCING SCATTERED CONVECTION AS MENTIONED ABOVE. WEAK HIGH PRESSURE ACROSS THE W COAST OF THE GULF OF MEXICO IS FORECAST TO SQUEEZE SOUTHWARD AND INDUCE FRESH FLOW THROUGH THE GULF OF TEHUANTEPEC TO LAST THROUGH EARLY MONDAY MORNING. MARINE CONDITIONS OTHERWISE REMAIN MILD ACROSS THE AREA WITH LONG PERIOD NWLY SWELL EXPECTED TO BEGIN TO MERGE WITH SWLY SWELL FROM THE SOUTHERN HEMISPHERE TODAY S OF 10N. AS HILARY CONTINUES MOVING WNW...SE SWELL WILL BEGIN TO MOVE INTO S PORTIONS OF THE GULF OF CALIFORNIA BY SUNDAY MORNING AND CONTINUE NW INSIDE THE GULF THROUGH MONDAY. $$ STRIPLING