743 
 WTPZ45 KNHC 182037
 TCDEP5
 HURRICANE RICK DISCUSSION NUMBER  14
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP202009
 200 PM PDT SUN OCT 18 2009
  
 INFRARED SATELLITE IMAGERY SHOWS THAT THE CLOUD STRUCTURE OF RICK
 CONTINUES TO SLOWLY DETERIORATE. CLOUD TOPS HAVE WARMED AROUND
 THE EYE...AS THE OVERALL COVERAGE OF THE COLDEST TOPS HAS DECREASED.  
 ALSO...THE WESTERN SIDE OF THE CLOUD SHIELD HAS THINNED...WITH A
 TONGUE OF DRY AIR EVIDENT IN VISIBLE AND MICROWAVE IMAGERY ABOUT 100
 MILES FROM THE CENTER. CONSISTENT WITH THESE TRENDS...SATELLITE
 INTENSITY ESTIMATES HAVE DECREASED. DVORAK FINAL-T AND CI NUMBERS
 WERE 6.5/7.5 FROM BOTH TAFB AND SAB. THE INITIAL INTENSITY IS
 REDUCED TO 140 KT FOR THIS PACKAGE. 
 
 WHILE THE ENVIRONMENT AROUND RICK REMAINS FAVORABLE FOR THE NEXT DAY
 OR SO...MOST OF THE INTENSITY GUIDANCE SHOWS A DOWNWARD TREND IN
 THE SHORT TERM. THE OFFICIAL FORECAST FOLLOWS SUIT...BUT STILL LIES
 ABOVE THE GUIDANCE THROUGH 24 HOURS. BEYOND THAT TIME...VERTICAL
 SHEAR WILL INCREASE AHEAD OF AN UPPER TROUGH AND RICK WILL BE
 MOVING OVER COOLER SSTS AND INTO A LESS FAVORABLE THERMODYNAMIC
 ENVIRONMENT. THE OFFICIAL FORECAST BEYOND 24 HOURS IS A BLEND OF THE
 SHIPS...LGEM...AND THE GFDL. RICK IS EXPECTED TO STILL BE A
 HURRICANE AS IT APPROACHES BAJA AND WILL WEAKEN RAPIDLY AFTER
 LANDFALL IN MAINLAND MEXICO. 
  
 THE INITIAL MOTION ESTIMATE IS 295/12. RICK IS CURRENTLY SITUATED
 SOUTH OF A SUBTROPICAL RIDGE THAT IS CENTERED OVER NORTHWESTERN
 MEXICO. THIS RIDGE WILL BEGIN TO WEAKEN IN THE NEXT 24 HOURS AS
 A MID- TO UPPER-LEVEL TROUGH CENTERED ALONG 135W AMPLIFIES AND
 MOVES INTO THE WESTERN UNITED STATES. THIS TROUGH WILL FORCE RICK TO
 TURN NORTHWARD AND THEN NORTHEASTWARD IN 36 TO 48 HOURS. THERE IS
 SOME DISAGREEMENT ABOUT THE HOW QUICKLY RICK WILL MOVE AS IT
 RECURVES. BY 72 HOURS...THE ECMWF...GFDL AND GFDN ARE CONSIDERABLY
 FASTER...WHILE THE GFS...NOGAPS...AND CANADIAN MODEL ARE SLOWER.
 THIS SPREAD APPEARS TO BE DUE TO DIFFERENCES IN THE DETAILS OF HOW
 RICK INTERACTS WITH THE UPPER TROUGH IN THE VARIOUS MODELS. THE
 OFFICIAL FORECAST IS A BLEND OF THE PREVIOUS PACKAGE AND THE
 MULTI-MODEL CONSENSUS AND LIES CLOSE TO A BLEND OF THE ECMWF...
 GFS...NOGAPS...GFDL...AND THE FSU SUPERENSEMBLE.
  
 ALTHOUGH WEAKENING IS FORECAST...RICK IS EXPECTED TO STILL BE A
 DANGEROUS HURRICANE AS IT APPROACHES THE SOUTHERN BAJA PENINSULA IN
 TWO OR THREE DAYS. A HURRICANE WATCH MAY BE REQUIRED FOR PORTIONS OF
 SOUTHERN BAJA TONIGHT OR 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      18/2100Z 16.4N 109.4W   140 KT
  12HR VT     19/0600Z 17.1N 110.7W   130 KT
  24HR VT     19/1800Z 18.3N 111.7W   120 KT
  36HR VT     20/0600Z 19.4N 111.9W   105 KT
  48HR VT     20/1800Z 20.7N 111.4W    95 KT
  72HR VT     21/1800Z 24.0N 109.0W    75 KT
  96HR VT     22/1800Z 26.0N 106.5W    45 KT...INLAND
 120HR VT     23/1800Z...DISSIPATED
  
 $$
 FORECASTER BRENNAN
  
 

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