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ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Hurricane Helene Discussion Number 18 NWS National Hurricane Center Miami FL AL082018 500 PM AST Tue Sep 11 2018 Helene is feeling the effects of cooler waters, and the convection surrounding the distinct eye is weaker that earlier today. Dvorak numbers are decreasing, and only support an initial intensity of 90 kt. Both cooler waters and high shear will continue to impact the hurricane, and Helene will probably weaken to a tropical storm in about 36 hours or so. The NHC forecast calls for a decrease in the winds at the same rate as the intensity consensus aids. Helene is already on the southwestern side of the subtropical ridge, and it is now moving toward the northwest or 320 degrees at 10 kt. Global models continue to develop a large mid-level trough over eastern Atlantic, and the flow associated with this trough should steer Helene north-northwestward and northward during the next day to so. The cyclone should then recurve northeastward with an increase in forward speed and by Friday, a weakened Helene should be approaching the Azores. At the very long range, the cyclone will begin to lose tropical characteristics over the even colder waters of the north Atlantic. There has been little change in the track forecast since models have been very consistent with the current solution. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 17.2N 34.9W 90 KT 105 MPH 12H 12/0600Z 18.3N 36.0W 80 KT 90 MPH 24H 12/1800Z 20.2N 37.2W 70 KT 80 MPH 36H 13/0600Z 22.3N 37.8W 60 KT 70 MPH 48H 13/1800Z 25.0N 38.0W 50 KT 60 MPH 72H 14/1800Z 31.5N 37.0W 45 KT 50 MPH 96H 15/1800Z 39.0N 32.5W 45 KT 50 MPH 120H 16/1800Z 43.5N 25.0W 45 KT 50 MPH $$ Forecaster Avila NNNN