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