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ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Hurricane Helene Discussion Number 17 NWS National Hurricane Center Miami FL AL082018 1100 AM AST Tue Sep 11 2018 It appears that Helene already peaked in intensity earlier this morning with 95 kt. The cloud pattern has not changed much, and still consists of a large eye surrounded by deep convection. However, these convective tops have warmed a little, and consequently Dvorak numbers have remained steady. From now on, Helene will begin to move over increasingly cooler waters, and become embedded within higher shear in about a day. These environmental conditions should result in weakening, and the NHC forecast calls for a decrease in the winds at the same rate as the intensity consensus aids. Helene has turned toward the northwest or 310 degrees at 10 kt. Models continue to erode the ridge to the north of the cyclone, and are also developing a large mid-level trough over eastern Atlantic. This forecast flow pattern will force Helene to turn more toward the north-northwest and north ahead of the trough for the next 2 to 3 days. After that time, the cyclone will recurve in the mid- latitude westerlies, and will begin to lose tropical characteristics at the very long ranges. Track models are in very good agreement with this solution. The NHC forecast is in the middle of the guidance envelope and in between HCCA and the multi-model consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 16.5N 34.3W 95 KT 110 MPH 12H 12/0000Z 17.5N 35.5W 90 KT 105 MPH 24H 12/1200Z 18.9N 36.9W 80 KT 90 MPH 36H 13/0000Z 20.7N 37.8W 70 KT 80 MPH 48H 13/1200Z 22.5N 38.2W 60 KT 70 MPH 72H 14/1200Z 27.5N 38.0W 50 KT 60 MPH 96H 15/1200Z 35.0N 35.0W 50 KT 60 MPH 120H 16/1200Z 40.0N 30.0W 50 KT 60 MPH $$ Forecaster Avila NNNN