102 
 WTPZ45 KNHC 190244
 TCDEP5
 HURRICANE RICK DISCUSSION NUMBER  15
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP202009
 800 PM PDT SUN OCT 18 2009
  
 DRY AIR AND SOUTHWESTERLY SHEAR...LOCATED BENEATH THE CIRRUS OUTFLOW
 LAYER...HAVE CONTINUED TO ERODE THE DEEP CONVECTION ON THE WESTERN
 SIDE OF THE HURRICANE.  THE EYE REMAINS DISTINCT IN INFRARED
 IMAGERY...AND A 2101 AMSR-E MICROWAVE PASS SUGGESTED THAT THE
 HURRICANE HAD A PARTIAL CONCENTRIC EYEWALL STRUCTURE.  THE
 DEGRADATION OF THE CLOUD PATTERN HAS RESULTED IN DVORAK FINAL-T AND
 CI NUMBERS OF 6.5/7.0 FROM TAFB AND 6.0/7.0 FROM SAB.  IN
 ADDITION...THE OBJECTIVE ESTIMATE FROM UW-CIMSS IS NOW 6.1/6.7...
 AND THE ADVISORY INTENSITY IS SET AT 125 KT.
  
 RICK IS TURNING NORTHWESTWARD WITH AN INITIAL MOTION OF 305 DEGREES
 AT 11 KT NOW THAT THE SUBTROPICAL RIDGE TO ITS NORTH HAS BEGUN TO
 WEAKEN.  THE RIDGE IS EXPECTED TO CONTINUE TO BREAK DOWN AS A
 SHORTWAVE TROUGH LOCATED WEST OF NORTHERN CALIFORNIA MOVES EAST AND
 AMPLIFIES OVER THE WESTERN UNITED STATES OVER THE NEXT 48 HOURS.
 AS A RESULT...THE EVOLVING STEERING FLOW WILL TURN RICK TOWARD THE
 NORTH AND NORTH-NORTHEAST OVER THE NEXT COUPLE OF DAYS.  ONLY THE
 UKMET CONTINUES TO SHOW A WESTWARD MOTION DURING THAT TIME...AND A
 CONSENSUS OF THE OTHER DYNAMICAL MODELS SUGGESTS THAT RICK WILL
 ACCELERATE TOWARD THE NORTHEAST BY DAY 3.  THE NEW NHC FORECAST IS
 VERY CLOSE TO THAT CONSENSUS AND NOT VERY DIFFERENT FROM THE
 PREVIOUS FORECAST.
  
 ADDITIONAL WEAKENING IS EXPECTED OVER THE NEXT FEW DAYS DUE TO
 INCREASING VERTICAL SHEAR AND INGESTION OF DRY AND MORE STABLE AIR
 LOCATED TO THE WEST OF THE HURRICANE.  THE NEW OFFICIAL FORECAST IS
 A LITTLE FASTER IN WEAKENING RICK THAN WAS SHOWN IN PREVIOUS
 FORECASTS...BUT THIS IS MAINLY DUE TO THE FACT THAT THE INITIAL
 INTENSITY IS ALREADY LOWER THAN EXPECTED.  MOST IMPORTANTLY...RICK
 IS STILL EXPECTED TO BE A SIGNIFICANT HURRICANE AS IT MOVES NEAR
 THE SOUTHERN TIP OF BAJA CALIFORNIA AND INTO NORTHWESTERN MEXICO IN
 2 TO 3 DAYS.  A 96-HOUR POSITION IS SHOWN TO MAINTAIN CONTINUITY IN
 THE INTENSITY FORECAST...BUT IT IS DOUBTFUL THAT A WELL-DEFINED
 SURFACE CENTER WILL EXIST AT THAT TIME.
  
 A HURRICANE WATCH MAY BE REQUIRED FOR PORTIONS OF SOUTHERN BAJA
 EARLY MONDAY.  INTERESTS THROUGHOUT SOUTHERN BAJA AND ALONG THE
 WEST-CENTRAL COAST OF MAINLAND MEXICO SHOULD CLOSELY MONITOR THE
 PROGRESS OF RICK.
   
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      19/0300Z 17.0N 110.3W   125 KT
  12HR VT     19/1200Z 17.9N 111.2W   115 KT
  24HR VT     20/0000Z 19.0N 111.8W   105 KT
  36HR VT     20/1200Z 20.2N 111.6W    95 KT
  48HR VT     21/0000Z 21.7N 110.6W    85 KT
  72HR VT     22/0000Z 25.0N 107.5W    70 KT...INLAND
  96HR VT     23/0000Z 26.5N 106.0W    30 KT...INLAND
 120HR VT     24/0000Z...DISSIPATED
  
 $$
 FORECASTER BERG
  
 

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