ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM HURRICANE HILARY DISCUSSION NUMBER 24 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092011 800 PM PDT MON SEP 26 2011 THE CLOUD PATTERN ASSOCIATED WITH HILARY HAS DEGRADED SINCE THIS AFTERNOON WITH THE EYE FILLING AND THE CONVECTIVE CLOUD TOPS WARMING. AS A RESULT...SUBJECTIVE DVORAK AND UW-CIMSS ADT T-NUMBERS HAVE DECREASED A LITTLE...AND A BLEND OF THESE NUMBERS YIELDS AN INITIAL INTENSITY OF 110 KT. HILARY HAS STARTED ITS PROGRESSION OVER SLIGHTLY COOLER SSTS...AND GRADUAL WEAKENING IS PREDICTED OVER THE NEXT DAY OR SO. IN 2 TO 3 DAYS...THE HURRICANE SHOULD CROSS THE 26C ISOTHERM AND OVER MUCH COLDER WATER DURING THE REMAINDER OF THE PERIOD. THIS...COMBINED WITH INCREASING SOUTHWESTERLY SHEAR...SHOULD CAUSE HILARY TO RAPIDLY WEAKEN. THE NHC INTENSITY FORECAST IS CLOSE TO THE INTENSITY CONSENSUS DURING THE FIRST 36 HOURS...AND THEREAFTER IT IS IN GOOD AGREEMENT WITH THE LGEM MODEL. HILARY HAS BEEN MOVING NEARLY DUE WESTWARD DURING THE PAST SEVERAL HOURS AT A SLIGHTLY SLOWER FORWARD SPEED OF 8 KT. WATER VAPOR IMAGERY SHOWS THAT THE MID- TO UPPER-LEVEL LOW NEAR 28N131W IS BEGINNING TO SLIDE EASTWARD. AS THIS OCCURS...THE RIDGE THAT HAS BEEN STEERING HILARY WESTWARD FOR THE PAST SEVERAL DAYS SHOULD WEAKEN. THE HURRICANE IS THEN FORECAST TO TURN SHARPLY NORTHWARD AROUND THE EASTERN PERIPHERY OF THE MID/UPPER-LOW AS IT MOVES SOUTHEASTWARD. THE LATEST RUN OF THE GFS MODEL REMAINS ALONG THE FAR EASTERN EDGE OF THE MODEL ENVELOPE...TURNING HILARY NORTHWARD MUCH SOONER THAN THE REMAINDER OF THE GUIDANCE. THE EARLIER NORTHWARD AND NORTHEASTWARD MOTION SHOWN BY THIS MODEL KEEPS HILARY OVER WARMER WATER AND IN LESS SHEAR...AND CONSEQUENTLY MAINTAINS THE CYCLONE AS A DEEP SYSTEM THAT MOVES QUICKLY NORTHEASTWARD ACROSS THE BAJA PENINSULA. THE REMAINDER OF THE GUIDANCE SHOWS THE HURRICANE MOVING MORE WESTWARD DURING THE NEXT DAY OR SO...WHICH RESULTS IN THE CYCLONE REACHING COOLER WATER SOONER. THE LATTER MODELS THEN WEAKEN HILARY AND DEPICT A SHALLOW SYSTEM THAT SLOWS DOWN AND EVENTUALLY TURNS NORTHWESTWARD IN THE LOW- TO MID-LEVEL FLOW. THE NHC FORECAST PUTS LESS WEIGHT ON THE GFS SOLUTION...BUT IS NOT NEARLY AS FAR LEFT AS THE ECMWF AND UKMET MODELS. THE NEW TRACK HAS BEEN ADJUSTED A LITTLE WEST OF THE PREVIOUS ADVISORY AND IS CLOSE TO A CONSENSUS OF THE GFDL...HWRF... NOGAPS...AND ECMWF MODELS. FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 16.6N 114.8W 110 KT 125 MPH 12H 27/1200Z 16.8N 115.8W 105 KT 120 MPH 24H 28/0000Z 17.2N 116.6W 95 KT 110 MPH 36H 28/1200Z 17.9N 116.9W 90 KT 105 MPH 48H 29/0000Z 19.1N 116.9W 80 KT 90 MPH 72H 30/0000Z 21.7N 116.9W 60 KT 70 MPH 96H 01/0000Z 24.0N 117.0W 35 KT 40 MPH 120H 02/0000Z 26.5N 117.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ FORECASTER BROWN NNNN
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