000 WTNT41 KNHC 170259 TCDAT1 HURRICANE IGOR DISCUSSION NUMBER 36 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 1100 PM AST THU SEP 16 2010 THE CLOUD PATTERN OF IGOR HAS CHANGED LITTLE THIS EVENING. DVORAK CURRENT INTENSITY NUMBERS FROM SAB AND TAFB ARE 5.5 AND 6.0... RESPECTIVELY. THIS SUPPORTS MAINTAINING AN INITIAL INTENSITY OF 110 KT. THE EYE OF IGOR IS PASSING VERY NEAR NOAA BUOY 41044. THROUGH 0200 UTC...THE 5-METER HIGH ANEMOMETER ON THE BUOY HAS REPORTED PEAK 1-MINUTE SUSTAINED WINDS OF 69 KT WITH A GUST TO 91 KT. A MINIMUM PRESSURE OF 940.3 MB WAS RECORDED AT 0050 UTC WITH WINDS AROUND 60 KT. THIS SUGGESTS THAT THE MINIMUM PRESSURE IS AROUND 935 MB. DUE TO THE LARGE SIZE AND RELATIVELY SLOW MOTION OF THE HURRICANE...THE BUOY HAS NOW REPORTED TROPICAL STORM FORCE WINDS FOR 21 CONSECUTIVE HOURS. IGOR IS EXPECTED TO REMAIN OVER WARM WATER AND IN A FAVORABLE UPPER-LEVEL ENVIRONMENT WITH SHEAR LESS THAN 15 KT DURING THE NEXT DAY OR TWO. SOME RE-STRENGTHENING IS POSSIBLE DURING THIS TIME...AND THE SHORT-TERM INTENSITY WILL LIKELY BE DICTATED BY EYEWALL CYCLES THAT ARE DIFFICULT TO PREDICT. AFTER 48 HOURS... SOUTHWESTERLY SHEAR IS FORECAST TO GRADUALLY INCREASE AND IGOR WILL BE MOVING OVER COOLER SSTS IN 4-5 DAYS. THIS WILL RESULT IN GRADUAL WEAKENING...HOWEVER IGOR IS EXPECTED TO REMAIN A LARGE AND POWERFUL HURRICANE FOR SEVERAL MORE DAYS. BY THE END OF THE FORECAST PERIOD IGOR WILL BE UNDERGOING EXTRATROPICAL TRANSITION. IGOR HAS BEEN MOVING NORTHWESTWARD OR 310 DEGREES AT 7 KT. THE HURRICANE IS FORECAST TO MOVE AROUND THE WESTERN PORTION OF THE SUBTROPICAL RIDGE DURING THE NEXT 2-3 DAYS. THEREAFTER...IGOR WILL ACCELERATE AND TURN NORTHEASTWARD AHEAD OF A MID-LATITUDE TROUGH THAT IS FORECAST TO MOVE THROUGH THE NORTHEAST UNITED STATES IN A FEW DAYS. THE TRACK GUIDANCE HAS CHANGED LITTLE AND NEITHER HAS THE OFFICIAL FORECAST...WHICH LIES NEAR THE MULTI-MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 17/0300Z 22.0N 58.7W 110 KT 12HR VT 17/1200Z 23.0N 60.0W 115 KT 24HR VT 18/0000Z 24.2N 61.7W 115 KT 36HR VT 18/1200Z 25.7N 63.3W 115 KT 48HR VT 19/0000Z 27.3N 64.4W 110 KT 72HR VT 20/0000Z 31.7N 65.1W 100 KT 96HR VT 21/0000Z 37.5N 60.0W 85 KT 120HR VT 22/0000Z 45.5N 47.0W 70 KT $$ FORECASTER BROWN