864 
 WTPZ43 KNHC 311435
 TCDEP3
 HURRICANE JIMENA DISCUSSION NUMBER  12
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132009
 800 AM PDT MON AUG 31 2009
 
 THE EYE HAS BEEN COMING AND GOING ON INFRARED IMAGERY AND...BASED ON
 MICROWAVE IMAGERY...APPEARS TO BE A LITTLE LARGER THAN IT WAS
 YESTERDAY.  THE MICROWAVE IMAGES EARLIER THIS MORNING ALSO
 SUGGESTED THAT JIMENA MAY HAVE UNDERGONE AN EYEWALL REPLACEMENT. 
 DVORAK SUBJECTIVE AND OBJECTIVE DATA T-NUMBERS HAVE DECREASED A
 LITTLE OVER THE PAST 12 HOURS...SO JIMENA MAY HAVE WEAKENED
 SLIGHTLY.  HOWEVER...I WILL HOLD THE CURRENT INTENSITY AT 125 KT
 UNTIL AIR FORCE RECONNAISSANCE INVESTIGATES THE HURRICANE A LITTLE
 LATER TODAY AND GIVES US SOME IN SITU MEASUREMENTS.  THE WATERS ARE
 WARM ALONG THE PROJECTED TRACK...BUT NOT QUITE AS WARM AFTER ABOUT
 24 HOURS AND WITH REDUCED OCEANIC HEAT CONTENT.  ALSO...THE GLOBAL
 MODELS INDICATE SOME INCREASE IN SOUTHWESTERLY SHEAR IN 24-48
 HOURS.  HOWEVER NONE OF THESE FACTOR ARE LIKELY TO PREVENT JIMENA
 FROM REMAINING A MAJOR HURRICANE UP TO LANDFALL.  THE OFFICIAL
 INTENSITY FORECAST IS A BLEND OF THE SHIPS AND LGEM MODELS...WHICH
 HISTORICALLY HAVE BEEN OUR BEST INTENSITY GUIDANCE.
 
 INITIAL MOTION IS ESTIMATED TO BE 315/7.  THE STEERING SCENARIO
 REMAINS MORE OR LESS THE SAME.  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 DYNAMICAL
 TRACK PREDICTION MODELS ARE IN REASONABLY GOOD AGREEMENT OVER THE
 NEXT 48 HOURS...WITH THE EXCEPTION OF THE U.K. MET. OFFICE GLOBAL
 AND THE LOW-RESOLUTION GFS ENSEMBLE MEAN WHICH ARE CONSIDERED
 WESTERN OUTLIERS AT THIS TIME.  IN FACT...THE MEAN OF THE
 HIGHER-RESOLUTION PARALLEL RUN OF THE GFS IS FAIRLY CLOSE TO THE
 MIDDLE OF THE GUIDANCE ENVELOPE.  THE OFFICIAL FORECAST IS FAIRLY
 SIMILAR TO THE PREVIOUS ONE AND NOT FAR FROM THE MODEL CONSENSUS.
 
 BASED ON THE FORECAST...THE GOVERNMENT OF MEXICO HAS ISSUED A
 HURRICANE WARNING FOR A PORTION OF THE SOUTHERN BAJA CALIFORNIA
 PENINSULA AND A HURRICANE WATCH FARTHER NORTH ALONG THE BAJA
 PENINSULA.
 
 INTERESTS IN THE WARNING AREA ARE REMINDED...DO NOT FORECAST ON THE
 EXACT FORECAST TRACK.  A HURRICANE IS NOT A POINT AND DANGEROUS
 IMPACTS EXTEND SOME DISTANCE FROM THE CENTER.  MOREOVER...TRACK
 FORECAST ERRORS CAN EASILY BE 50 TO 75 MILES IN THE 24 TO 36 HOURS
 TIME FRAME.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      31/1500Z 18.0N 108.3W   125 KT
  12HR VT     01/0000Z 19.1N 109.2W   125 KT
  24HR VT     01/1200Z 21.0N 110.3W   125 KT
  36HR VT     02/0000Z 23.0N 111.2W   115 KT
  48HR VT     02/1200Z 25.0N 111.9W    95 KT...INLAND
  72HR VT     03/1200Z 27.6N 112.9W    50 KT...INLAND
  96HR VT     04/1200Z 29.0N 113.5W    30 KT...INLAND
 120HR VT     05/1200Z 30.0N 114.0W    25 KT...OVER WATER
  
 $$
 FORECASTER PASCH