000 WTPZ44 KNHC 280251 TCDEP4 HURRICANE HILARY DISCUSSION NUMBER 28 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092011 800 PM PDT TUE SEP 27 2011 THE CLOUD PATTERN OF HILARY HAS DEGRADED THIS EVENING WITH THE EYE BECOMING LESS DISCERNIBLE IN GEOSTATIONARY IMAGES. HOWEVER...RECENT MICROWAVE DATA CONTINUE TO SHOW A RATHER DISTINCT EYE...BUT THE CONVECTION IN THE NORTHWESTERN PORTION OF THE CYCLONE HAS WEAKENED. CURRENT INTENSITY NUMBERS FROM TAFB...SAB...AND UW-CIMSS ALL SUPPORT AN INITIAL INTENSITY OF 90 KT. HILARY IS FORECAST TO MOVE OVER COOLER WATER AND INTO A MORE STABLE ENVIRONMENT DURING THE NEXT DAY OR SO...WHICH SHOULD RESULT IN STEADY WEAKENING. A PERIOD OF RAPID WEAKENING IS LIKELY AFTER 24 HOURS...AS SOUTHWESTERLY SHEAR INCREASES AND THE HURRICANE MOVES OVER SSTS OF LESS THAN 26 DEGREES CELSIUS. THE NHC INTENSITY FORECAST IS A BLEND OF THE SHIPS/LGEM MODELS AND FLORIDA STATE SUPERENSEMBLE GUIDANCE. THE FORECAST SHOWS HILARY TO BECOMING A POST-TROPICAL REMNANT LOW IN ABOUT 72 HOURS. IT APPEARS THAT THE MUCH ANTICIPATED NORTHWESTWARD TURN HAS COMMENCED AND THE INITIAL MOTION ESTIMATE IS 310/6. HILARY SHOULD TURN NORTHWARD DURING THE NEXT DAY OR SO AROUND THE EASTERN SIDE OF AN AMPLIFYING MID-LEVEL LOW. THE NORTHWARD MOTION SHOULD THEN CONTINUE THROUGH 72 HOURS. AFTER HILARY BECOMES A REMNANT LOW...IT IS LIKELY TO SLOW DOWN AND TURN NORTHWESTWARD. THE TRACK GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT WHICH YIELDS MORE CONFIDENCE IN THIS FORECAST. THE UPDATED NHC TRACK IS BETWEEN THE GFS AND ECMWF MODELS...AND A LITTLE TO THE RIGHT OF THE TVCE MULTI-MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 28/0300Z 17.4N 117.7W 90 KT 105 MPH 12H 28/1200Z 18.1N 118.1W 80 KT 90 MPH 24H 29/0000Z 19.0N 118.3W 70 KT 80 MPH 36H 29/1200Z 20.1N 118.4W 55 KT 65 MPH 48H 30/0000Z 21.3N 118.5W 40 KT 45 MPH 72H 01/0000Z 23.3N 119.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 02/0000Z 25.0N 120.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 03/0000Z 25.5N 120.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ FORECASTER BROWN