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Hurricane HELENE


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


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