075 
 WTPZ43 KNHC 020259
 TCDEP3
 HURRICANE JIMENA DISCUSSION NUMBER  18
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132009
 800 PM PDT TUE SEP 01 2009
  
 SINCE THE AIR FORCE PLANE LEFT THIS AFTERNOON...VISIBLE AND INFRARED
 SATELLITE IMAGES INDICATE THAT JIMENA HAS CONTINUED TO WEAKEN.  THE
 EYE HAS BECOME OBSCURED AND THERE HAS BEEN A GRADUAL SHRINKING OF
 THE CONVECTIVE COVERAGE.  FURTHERMORE...THERE HAS BEEN AN APPARENT
 DETERIORATION TO THE INNER CORE.  DVORAK T-NUMBERS HAVE FALLEN TO
 T4.5 AND T5.0 FROM SAB AND TAFB...RESPECTIVELY.  BASED UPON THE
 DEGRADED SATELLITE APPEARANCE BUT ALSO USING CONTINUITY...THE
 INITIAL INTENSITY IS LOWERED TO 100 KT.
  
 THE INITIAL MOTION ESTIMATE IS 345/11...SLIGHTLY TO THE RIGHT THAN
 BEFORE.  THE TRACK FORECAST PHILOSOPHY IS UNCHANGED.  ACCORDING TO
 THE TRACK MODEL GUIDANCE...JIMENA SHOULD CONTINUE MOVING NORTH-
 NORTHWESTWARD BETWEEN A MID- TO UPPER-LEVEL LOW WEST OF THE BAJA
 PENINSULA AND A MID-LEVEL RIDGE OVER NORTHERN MEXICO FOR AT LEAST
 FOR THE NEXT 24 TO 36 HOURS.  INCREASINGLY DIVERGENT MODEL
 SOLUTIONS SUGGEST A FORECAST OF LOWER CONFIDENCE BEYOND 48 HOURS.
 A MINORITY OF GLOBAL MODELS TAKES JIMENA NORTHEASTWARD OR EASTWARD
 INTO NORTHWESTERN MEXICO...WITH ONLY ONE TAKING IT INTO THE
 SOUTHWESTERN UNITED STATES. A LARGER NUMBER OF MODEL RUNS EITHER
 STALL JIMENA OVER CENTRAL BAJA CALIFORNIA...LIKE THE GFDL...OR TURN
 THE CYCLONE NORTHWESTWARD OR EVEN WESTWARD INTO THE EAST PACIFIC IN
 RESPONSE MID-LEVEL RIDGING BUILDING TO ITS NORTH.  THE NEW OFFICIAL
 FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY BUT SHIFTED
 INITIALLY TO THE RIGHT DUE TO THE CURRENT MORE NORTHERLY MOTION.
 THE FORECAST IS SOMEWHAT SLOWER AND TO THE LEFT OF THE PREVIOUS
 TRACK BEYOND 72 HOURS AS A RESULT OF THE MODEL CONSENSUS WHICH HAS
 BEEN TRENDING MORE WESTWARD.
  
 THE WEAKENING CAUSED BY AN EARLIER EYEWALL REPLACEMENT CYCLE HAS
 CONTINUED...LIKELY AS A RESULT OF GRADUALLY COOLER SSTS AND
 INCREASING WESTERLY SHEAR.  UW CIMSS ANALYSES SUGGESTS 10-15 KT OF
 WESTERLY SHEAR OVER JIMENA...WHICH SEEMS BELIEVABLE GIVEN THE MORE
 ASYMMETRIC ORGANIZATION OF THE CORE CONVECTION DURING THE LAST FEW
 HOURS. PRIOR TO LANDFALL IN 12 TO 24 HOURS...THE GUIDANCE AGREES
 WELL ON A CONTINUED...STEADY WEAKENING.  THEREAFTER...STRONGER
 WESTERLY SHEAR AND THE CENTER TRACKING MOVING OVER LAND SHOULD LEAD
 TO A MORE RAPID WEAKENING... WITH THE OFFICIAL FORECAST NOW CALLING
 FOR JIMENA TO BECOME A REMNANT LOW BY 96 HR.  THERE REMAINS A
 CHANCE THAT JIMENA COULD WEAKEN FASTER 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      02/0300Z 23.2N 111.3W   100 KT
  12HR VT     02/1200Z 24.6N 112.0W    90 KT
  24HR VT     03/0000Z 26.2N 112.6W    75 KT
  36HR VT     03/1200Z 27.3N 112.9W    60 KT...INLAND
  48HR VT     04/0000Z 28.0N 113.2W    40 KT...INLAND
  72HR VT     05/0000Z 28.5N 113.5W    30 KT...INLAND
  96HR VT     06/0000Z 29.5N 114.0W    20 KT...REMNANT LOW
 120HR VT     07/0000Z 30.0N 114.0W    20 KT...REMNANT LOW
  
 $$
 FORECASTER KIMBERLAIN