000 WTPZ43 KNHC 312034 TCDEP3 HURRICANE JIMENA DISCUSSION NUMBER 13 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP132009 200 PM PDT MON AUG 31 2009 THE AIR FORCE RESERVE HURRICANE HUNTERS HAVE JUST COMPLETED THEIR MISSION IN JIMENA...AND FOUND THAT THE HURRICANE WAS STRONGER THAN PREVIOUSLY ESTIMATED. PEAK 700 MB FLIGHT-LEVEL WINDS WERE 149 KT AND THE MAXIMUM SFMR-MEASURED SURFACE WINDS WERE 132 KT OVER THE NORTHEAST QUADRANT. THE SFMR ALSO MEASURED 128 KT IN THE NORTHWEST EYEWALL AND 125 KT IN THE SOUTHWEST PART OF THE EYEWALL. A MINIMUM CENTRAL PRESSURE OF 931 MB WAS MEASURED BY DROPSONDE. THE CURRENT INTENSITY IS ADJUSTED UPWARD TO 135 KT...AT THE VERY HIGH END OF CATEGORY 4 STATUS. FLUCTUATIONS IN STRENGTH ARE LIKELY DURING THE NEXT DAY OR SO DUE TO INNER CORE EVENTS...PRIMARILY EYEWALL REPLACEMENTS. HOWEVER THE SHIPS MODEL INDICATES A GRADUAL DECREASE IN OCEANIC HEAT CONTENT AND SOME INCREASE IN WEST-SOUTHWESTERLY SHEAR DURING THE NEXT 36 HOURS. HOWEVER THESE ENVIRONMENTAL INFLUENCES SHOULD NOT PREVENT JIMENA FROM MAINTAINING MAJOR HURRICANE STRENGTH PRIOR TO LANDFALL. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE SHIPS AND LGEM GUIDANCE. AFTER WOBBLING WEST-NORTHWESTWARD A FEW HOURS AGO...THE MOTION IS BACK TO NORTHWEST OR 315/9. THERE HAS BEEN LITTLE CHANGE TO THE TRACK FORECAST PHILOSOPHY. JIMENA IS LIKELY TO MOVE BETWEEN A MID-LEVEL RIDGE OVER NORTHWESTERN MEXICO AND A MID- TO UPPER-LEVEL CYCLONE JUST TO THE WEST OF THE BAJA PENINSULA. THE U.K. MET. OFFICE GLOBAL MODEL...LIKE THE ECMWF GLOBAL MODEL...PREVIOUSLY WESTERN OUTLIERS...HAVE SHIFTED EASTWARD AND ARE NOW IN GENERAL AGREEMENT WITH THE OTHER DYNAMICAL MODELS. HOWEVER THE U.K. AND ECMWF ARE STILL SOMEWHAT SLOWER THAN MOST OF THE GUIDANCE. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE AND ABOUT IN THE MIDDLE OF THE DYNAMICAL TRACK MODEL SUITE. NO CHANGES TO THE WATCHES AND WARNINGS ARE NECESSARY AT THIS TIME. INTERESTS IN THE WARNING AREA SHOULD BE ADVISED THAT STRONG WINDS WILL PRECEDE THE ARRIVAL OF THE CENTER BY SEVERAL HOURS...SO PREPARATIONS NEED TO BE COMPLETED AS EARLY AS POSSIBLE. ALSO...INTERESTS IN THE WARNING AREA ARE REMINDED...NOT TO FOCUS ON THE EXACT FORECAST TRACK. A HURRICANE IS NOT A POINT...AND DANGEROUS IMPACTS EXTEND SOME DISTANCE FROM THE CENTER. IN FACT...THE AIR FORCE RECONNAISSANCE OBSERVATIONS SHOW THAT JIMENA IS LARGER THAN PREVIOUS ESTIMATED. MOREOVER...TRACK FORECAST ERRORS CAN EASILY BE 50 TO 75 MILES IN THE 24 TO 36 HOUR TIME FRAME. FORECAST POSITIONS AND MAX WINDS INITIAL 31/2100Z 18.5N 109.2W 135 KT 12HR VT 01/0600Z 19.6N 110.1W 130 KT 24HR VT 01/1800Z 21.6N 111.1W 125 KT 36HR VT 02/0600Z 23.6N 111.8W 115 KT 48HR VT 02/1800Z 25.5N 112.2W 85 KT 72HR VT 03/1800Z 27.8N 112.7W 50 KT...INLAND 96HR VT 04/1800Z 29.5N 113.0W 50 KT...OVER WATER 120HR VT 05/1800Z 31.0N 113.0W 30 KT...INLAND $$ FORECASTER PASCH