000 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