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Hurricane Helene Discussion Number  14
NWS National Hurricane Center Miami FL       AL082018
500 PM AST Mon Sep 10 2018

Helene's cloud pattern continues to be well organized with a large
eye of about 20 nm in diameter, surrounded by a ring of deep
convection.  The cyclone's circulation is large with numerous
cyclonically curved convective bands, and the outflow is fair in all
quadrants. Dvorak classifications have not changed much, and support
an initial intensity of 90 kt.

Helene has the opportunity to strengthen some during the next 24
hours or so, while the shear is low and the ocean is still
relatively warm. After that time, both shear and SSTs will become
less favorable and gradual weakening should then begin. The NHC
intensity forecast is similar to the previous one, and follows
closely the intensity consensus aids.

Helene is moving toward the west-northwest or 290 degrees at 15 kt.
Soon, the hurricane will encounter a mid-level trough which the most
reliable global models are forming in the eastern Atlantic.
This new flow pattern will force Helene to turn to the northwest
and north ahead of the developing trough.  Track models are quite
consistent with this solution and the the spread of the guidance
envelope is small through the forecast period.  This increases the
confidence in the Helene's northward turn, followed by recurvature
over the eastern Atlantic.

FORECAST POSITIONS AND MAX WINDS

INIT  10/2100Z 14.9N  31.5W   90 KT 105 MPH
 12H  11/0600Z 15.5N  33.3W  100 KT 115 MPH
 24H  11/1800Z 16.4N  35.3W  100 KT 115 MPH
 36H  12/0600Z 17.5N  37.0W   85 KT 100 MPH
 48H  12/1800Z 19.0N  38.0W   75 KT  85 MPH
 72H  13/1800Z 23.0N  39.5W   60 KT  70 MPH
 96H  14/1800Z 28.5N  40.0W   50 KT  60 MPH
120H  15/1800Z 34.0N  37.0W   50 KT  60 MPH

$$
Forecaster Avila

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