529 
 WTPZ43 KNHC 012051
 TCDEP3
 HURRICANE JIMENA DISCUSSION NUMBER  17
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132009
 200 PM PDT TUE SEP 01 2009
  
 EARLIER DATA FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT
 INDICATED THAT JIMENA WAS COMPLETING ITS EYEWALL REPLACEMENT
 CYCLE...WITH THE INNER EYE DISSIPATING AND THE NEW EYE ABOUT
 25-30 N MI ACROSS.  THE AIRCRAFT DATA SUGGEST AN INTENSITY NEAR
 115 KT AT THAT TIME.  SINCE THEN...THE CLOUD TOPS NEAR THE CENTER
 HAVE WARMED AND THE EYE HAS NOT CLEARED OUT.  BASED ON THIS...IT IS
 ESTIMATED THAT JIMENA HAS WEAKENED A LITTLE MORE...AND THE INITIAL
 INTENSITY IS REDUCED TO 110 KT.
  
 THE INITIAL MOTION IS 330/10.  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
 REMAINING IN AGREEMENT WITH THIS SCENARIO.  THE FORECAST BECOMES
 LESS CONFIDENT FROM 72 HR ON DUE TO A LARGE SPREAD IN THE GUIDANCE.
 THE GFDL AND GFDN STILL 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.
 THIS APPEARS TO BE DUE TO HIGHER PRESSURES DEVELOPING NORTH OF THE
 CYCLONE...AND THE SYSTEM SHEARING APART AS STRONG UPPER-LEVEL
 WESTERLY FLOW DEVELOPS.  THE NEW FORECAST TRACK IS AN UPDATE OF THE
 PREVIOUS THROUGH THROUGH 72 HR...AND THEN IS SLOWER THAN THE
 PREVIOUS TRACK THEREAFTER.  THE NEW TRACK IS JUST RIGHT OF THE
 CENTER OF THE DYNAMICAL GUIDANCE THROUGH 72 HR...AND CLOSE TO THE
 MODEL CONSENSUS THEREAFTER.  THE NEW TRACK CALLS FOR LANDFALL ON
 THE CENTRAL BAJA CALIFORNIA PENINSULA IN ABOUT 36 HR.
  
 IT NOW APPEARS UNLIKELY THAT THERE WILL BE NOTABLE INTENSIFICATION
 AT THE END OF THE EYEWALL REPLACEMENT CYCLE...AS JIMENA IS STARTING
 TO MOVE OVER COOLER SEA SURFACE TEMPERATURES.  A FASTER WEAKENING
 SHOULD OCCUR AFTER LANDFALL...AND AN EVEN FASTER WEAKENING SHOULD
 OCCUR WITH THE ONSET OF STRONG WESTERLY VERTICAL SHEAR IN ABOUT 72
 HR.  THE NEW INTENSITY FORECAST IS SIGNIFICANTLY LOWER THAN THAT OF
 THE PREVIOUS ADVISORY...AND THERE IS A CHANCE THAT JIMENA COULD
 WEAKEN MORE THAN FORECAST AFTER LANDFALL.
  
 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      01/2100Z 21.9N 111.2W   110 KT
  12HR VT     02/0600Z 23.3N 112.0W   105 KT
  24HR VT     02/1800Z 25.2N 112.7W    95 KT
  36HR VT     03/0600Z 26.5N 113.1W    85 KT
  48HR VT     03/1800Z 27.6N 113.4W    55 KT...INLAND
  72HR VT     04/1800Z 28.5N 113.5W    35 KT...INLAND
  96HR VT     05/1800Z 29.5N 113.5W    25 KT...OVER WATER
 120HR VT     06/1800Z 30.5N 113.5W    20 KT...REMNANT LOW
  
 $$
 FORECASTER BEVEN