994 
WTNT43 KNHC 122041
TCDAT3

Hurricane Helene Discussion Number  22
NWS National Hurricane Center Miami FL       AL082018
500 PM AST Wed Sep 12 2018

The eye has continued to become less distinct in conventional
imagery, but the overall convective pattern remains well organized
and symmetric. Based on the latest Dvorak estimates, the initial
intensity is lowered to 75 kt. Most of the guidance show a
significant increase in the shear in 24 hours, but the SSTs are not
changing much for the next 2 days or so, thus gradual weakening is
forecast.  After that time, both shear and SSTs will become
highly unfavorable, resulting in additional weakening. By the end of
the forecast period, Helene should have acquired extratropical
characteristics.

The hurricane is moving toward the north or 350 degrees at 12 kt,
embedded in the southerly flow to the east of the digging trough
over the central Atlantic.  Since the trough is forecast to amplify,
Helene will be forced to turn to the north-northeast and northeast
with an increase in forward speed. The global models remain in
fairly good agreement on the current forecast track of Helene, and
they all bring the cyclone near the Azores in about 3 days.
Interests in those islands should closely monitor the progress of
Helene over the next several days.


FORECAST POSITIONS AND MAX WINDS

INIT  12/2100Z 21.4N  36.7W   75 KT  85 MPH
 12H  13/0600Z 23.1N  37.1W   70 KT  80 MPH
 24H  13/1800Z 26.0N  37.2W   60 KT  70 MPH
 36H  14/0600Z 29.0N  36.5W   55 KT  65 MPH
 48H  14/1800Z 32.5N  35.5W   55 KT  65 MPH
 72H  15/1800Z 39.0N  32.0W   50 KT  60 MPH
 96H  16/1800Z 43.0N  24.0W   45 KT  50 MPH
120H  17/1800Z 47.5N  14.5W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Avila