000 WTPZ45 KNHC 200838 TCDEP5 TROPICAL STORM RICK DISCUSSION NUMBER 20 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP202009 200 AM PDT TUE OCT 20 2009 CONVENTIONAL AND MICROWAVE SATELLITE IMAGES INDICATE THAT RICK CONTINUES TO FEEL THE EFFECTS OF SOUTHWESTERLY SHEAR. THE CLOUD PATTERN APPEARS RATHER DISORGANIZED...AND THE LOW-LEVEL CENTER IS EXPOSED TO THE SOUTHWEST OF A RECENT CONVECTIVE BURST. DVORAK FINAL T-NUMBERS OF 3.0 AND 3.5 FROM TAFB AND SAB...RESPECTIVELY... SUGGEST THAT SLOW WEAKENING HAS CONTINUED. BASED UPON THE LATEST INTENSITY ESTIMATES...THE INITIAL INTENSITY IS LOWERED TO 55 KT. UW-CIMSS SHEAR ANALYSES SUGGEST THAT 15-20 KT OF WEST-SOUTHWESTERLY SHEAR CONTINUES OVER RICK...AND GLOBAL MODELS INDICATE THIS SHOULD PERSIST THROUGH LANDFALL. IN ADDITION....A FAIRLY DRY AND STABLE AIR MASS AT MID/UPPER-LEVELS LIES IMMEDIATELY WEST OF THE STORM CIRCULATION AND CONTINUES TO NEGATIVELY IMPACT THE CYCLONE. THESE FACTORS SUGGEST ADDITIONAL...GRADUAL WEAKENING DURING THE NEXT DAY OR TWO...EVEN THOUGH SSTS INCREASE ALONG THE FORECAST TRACK. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE...IN BEST AGREEMENT WITH THE SHIPS...LGEM...AND THE MODEL INTENSITY CONSENSUS. IT SHOULD BE NOTED THAT THE GFDL AND HWRF FORECAST RICK TO RE-INTENSIFY TO A HURRICANE BEFORE LANDFALL. LATEST SATELLITE FIXES SUGGEST THAT RICK MAY HAVE TURNED TOWARD THE NORTH-NORTHEAST AND SLOWED DOWN DURING THE LAST SEVERAL HOURS... WITH THE LATEST INITIAL MOTION ESTIMATED AT 020/05. WATER VAPOR IMAGERY SHOWS A VIGOROUS SHORTWAVE TROUGH CURRENTLY DIGGING INTO THE GREAT BASIN...AND GLOBAL MODELS INDICATE THAT THIS FEATURE SHOULD AMPLIFY FURTHER OVER THE INTERMOUNTAIN WEST DURING THE NEXT 24-36 HOURS. IN RESPONSE...MODEL GUIDANCE SHOWS RICK TURNING NORTHEASTWARD WITH INCREASING FORWARD SPEED THROUGH LANDFALL IN WESTERN MAINLAND MEXICO. THE OFFICIAL FORECAST TRACK IS ADJUSTED FARTHER EAST TO MATCH THE TREND IN THE TRACK GUIDANCE AND MODEL CONSENSUS...BOTH SUGGESTING A SHARPER RECURVATURE. ON THIS TRACK...RICK IS EXPECTED TO PASS SOUTH OF SOUTHERN BAJA CALIFORNIA IN ABOUT 24 HOURS AND INLAND OVER WESTERN MAINLAND MEXICO JUST AFTER 36 HOURS. FORECAST POSITIONS AND MAX WINDS INITIAL 20/0900Z 19.4N 111.5W 55 KT 12HR VT 20/1800Z 20.6N 110.9W 50 KT 24HR VT 21/0600Z 22.0N 109.3W 50 KT 36HR VT 21/1800Z 23.6N 107.3W 45 KT 48HR VT 22/0600Z 25.5N 104.5W 20 KT...INLAND 72HR VT 23/0600Z...DISSIPATED $$ FORECASTER KIMBERLAIN