000 WTPZ44 KNHC 271434 TCDEP4 HURRICANE HILARY DISCUSSION NUMBER 26 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092011 800 AM PDT TUE SEP 27 2011 AFTER DECREASING OVERNIGHT...DEEP CONVECTION HAS INCREASED AGAIN NEAR THE CENTER OF HILARY...EVEN THOUGH AN EYE IS NO LONGER APPARENT IN INFRARED IMAGERY OR THE FIRST VISIBLE IMAGES. THE INITIAL INTENSITY IS HELD AT 100 KT BASED ON A BLEND OF 12Z DVORAK CI- AND FINAL-T NUMBERS FROM TAFB AND SAB. AS HILARY MOVES OVER COOLER WATERS IN THE NEXT DAY OR SO...SLOW WEAKENING IS EXPECTED... FOLLOWED BY STEADY WEAKENING AFTER THE CYCLONE CROSSES THE 26C ISOTHERM IN ABOUT 36 HOURS. OUTPUT FROM THE SHIPS MODEL SHOWS VERTICAL SHEAR INCREASING RAPIDLY AROUND 48 HOURS AND CONTINUING THROUGH THE REMAINDER OF THE PERIOD. THIS SHEAR...IN COMBINATION WITH HILARY MOVING OVER MUCH COLDER WATERS BY DAY 3 AND BEYOND SHOULD RESULT IN RAPID WEAKENING TO A REMNANT LOW BY 4 DAYS. THE NHC INTENSITY LIES BETWEEN THE OLD ONE AND THE LGEM THROUGH 36 HOURS...AND IS CLOSE TO THE LGEM BEYOND THAT TIME. THE INITIAL MOTION ESTIMATE IS 270/09. HILARY SHOULD TURN TOWARD THE WEST-NORTHWEST AND SLOW DOWN LATER TODAY AS THE RIDGE TO THE NORTH CONTINUES TO WEAKEN. AFTER THAT TIME A SHARP TURN TOWARD THE NORTH IS EXPECTED BY 36 HOURS AS HILARY BEGINS TO INTERACT WITH AN AMPLIFYING MID-LEVEL LOW CURRENTLY LOCATED NEAR 28N 129W. OVERALL...THE SPREAD OF THE TRACK GUIDANCE HAS DECREASED THIS CYCLE...AS THE LATEST RUN OF THE GFS SHOWS HILARY BEING PULLED A LITTLE FARTHER WESTWARD BY THE MID-LEVEL LOW LATE IN THE PERIOD AND HAS SHIFTED ITS TRACK WESTWARD TOWARD THE REST OF THE GUIDANCE SUITE. THE ONLY CHANGE TO THE NHC TRACK FORECAST IS A SMALL SHIFT TO THE LEFT THROUGH 48 HOURS TO ACCOUNT FOR THE INITIAL POSITION AND MOTION. THE NEW NHC TRACK IS A LITTLE TO THE EAST OF THE TVCE CONSENSUS AND THE ECMWF THROUGH 96 HOURS...AND IS CLOSE TO THE GFS ENSEMBLE MEAN AT DAY 5. FORECAST POSITIONS AND MAX WINDS INIT 27/1500Z 16.8N 116.4W 100 KT 115 MPH 12H 28/0000Z 17.1N 117.2W 95 KT 110 MPH 24H 28/1200Z 17.9N 117.6W 85 KT 100 MPH 36H 29/0000Z 19.0N 117.7W 75 KT 85 MPH 48H 29/1200Z 20.2N 117.7W 65 KT 75 MPH 72H 30/1200Z 23.0N 118.0W 45 KT 50 MPH 96H 01/1200Z 25.0N 118.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 02/1200Z 27.0N 118.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ FORECASTER BRENNAN