| HURRICANE JIMENA DISCUSSION NUMBER 16 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP132009 800 AM PDT TUE SEP 01 2009 MICROWAVE IMAGERY FROM THE NASA TRMM AND AQUA SATELLITES...ALONG WITH IR IMAGERY...INDICATE THAT JIMENA IS UNDERGOING AN EYEWALL REPLACEMENT CYCLE. THE SMALL EYE SEEN EARLIER IS BECOMING RAGGED AND CLOUD-FILLED...WHILE THE MICROWAVE DATA SHOWS AN OUTER EYEWALL ROUGHLY 30 N MI WIDE. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT HAS JUST REACHED THE CENTER...REPORTING THAT THE CENTRAL PRESSURE HAS RISEN TO 945 MB...AND THAT THE 700 MB FLIGHT-LEVEL WINDS ARE SIGNIFICANTLY LOWER THAN THOSE MEASURED YESTERDAY. THE INITIAL INTENSITY IS LOWERED TO 125 KT...AND THIS COULD BE GENEROUS. THE INITIAL MOTION IS WOBBLING BETWEEN 325 AND 330 DEGREES AT ABOUT 10 KT. JIMENA IS FORECAST TO CONTINUE IN A GENERAL NORTH- NORTHWESTERLY DIRECTION DURING THE NEXT COUPLE OF DAYS BETWEEN A MID/UPPER-LEVEL LOW WEST OF THE BAJA PENINSULA AND A MID-LEVEL RIDGE OVER NORTHERN MEXICO...WITH ALL THE TRACK GUIDANCE IN AGREEMENT WITH THIS SCENARIO. THE FORECAST BECOME LESS CONFIDENT FROM 72 HR ON DUE TO A LARGE SPREAD IN THE GUIDANCE. THE GFDL... GFDN...AND NOGAPS CALL FOR JIMENA TO TURN NORTHEASTWARD ACROSS NORTHWESTERN MEXICO AND THE SOUTHWESTERN UNITED STATES. THE REST OF THE DYNAMICAL GUIDANCE EITHER STALLS THE CYCLONE OVER CENTRAL BAJA CALIFORNIA OR TURNS IT WESTWARD INTO THE PACIFIC. OVERALL... THE GUIDANCE ENVELOPE HAS SHIFTED A LITTLE WESTWARD...AND SO HAS THE OFFICIAL FORECAST. AFTER 72 HR...THE NEW TRACK COMPROMISES BETWEEN THE MODEL EXTREMES BY CALLING FOR A SLOW NORTHWARD MOTION. THE NEW TRACK CALLS FOR LANDFALL ON THE CENTRAL BAJA CALIFORNIA PENINSULA IN 36-48 HR. THERE IS A CHANCE THAT JIMENA COULD INTENSIFY SOME AT THE END OF THE EYEWALL REPLACEMENT CYCLE IF THAT HAPPENS BEFORE THE CENTER REACHES COOLER SEA SURFACE TEMPERATURES. OTHERWISE...THE HURRICANE SHOULD WEAKEN OVER STEADILY COOLER WATER UNTIL LANDFALL...ALTHOUGH IT IS EXPECTED TO REMAIN A MAJOR HURRICANE UNTIL THAT TIME. JIMENA SHOULD WEAKEN FASTER DURING ITS TIME OVER BAJA. AFTER 72 HR...JIMENA COULD BE MOVING INTO THE WESTERLIES OVER NORTHWESTERN MEXICO... UNDER STRONG WESTERLY VERTICAL SHEAR OVER THE NORTHERN GULF OF CALIFORNIA...OR OVER COLD WATERS WEST OF THE BAJA PENINSULA. ALL OF THOSE POSSIBILITIES SUGGEST THAT THE CYCLONE SHOULD WEAKEN TO A REMNANT LOW BY 120 HR. INTERESTS IN THE HURRICANE WARNING AREA ARE ADVISED THAT STRONG WINDS WILL PRECEDE THE ARRIVAL OF THE CENTER BY SEVERAL HOURS...SO PREPARATIONS NEED TO BE COMPLETED VERY SOON. REMEMBER NOT TO FOCUS ON THE EXACT FORECAST TRACK SINCE DANGEROUS IMPACTS EXTEND SOME DISTANCE FROM THE CENTER. THE FORECAST TRACK OF JIMENA IS ALMOST PARALLEL TO THE COAST OF BAJA CALIFORNIA...AND SMALL DEVIATIONS LEFT OR RIGHT OF THE TRACK COULD RESULT IN LARGE ERRORS IN BOTH THE LOCATION AND TIMING OF LANDFALL. FORECAST POSITIONS AND MAX WINDS INITIAL 01/1500Z 21.0N 110.7W 125 KT 12HR VT 02/0000Z 22.4N 111.5W 125 KT 24HR VT 02/1200Z 24.3N 112.3W 115 KT 36HR VT 03/0000Z 25.9N 112.9W 100 KT 48HR VT 03/1200Z 27.1N 113.3W 70 KT...INLAND 72HR VT 04/1200Z 28.5N 113.5W 45 KT...INLAND 96HR VT 05/1200Z 30.0N 113.5W 30 KT...OVER WATER 120HR VT 06/1200Z 31.5N 113.0W 20 KT...INLAND $$ FORECASTER BEVEN |