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Tropical Storm Helene Discussion Number  31
NWS National Hurricane Center Miami FL       AL082018
1100 PM AST Fri Sep 14 2018

Data from a timely ASCAT pass indicate that Helene still carries
winds of 60 kt, primarily in the eastern semicircle.  The cloud
pattern continues to show a low-level center just south of the main
convection, marking the strong shear which is affecting the system.
Guidance indicates that Helene will not change much in intensity in
the next 12 hours, and only a slight decrease in the winds is
anticipated after that time.  The wind field is forecast to expand
mainly in the southeast quadrant, which is the area of the cyclone
that most likely will affect the Azores. After passing to the north
of, or near, the Azores in about 24 hours, Helene will be moving
over cold waters and become post-tropical.  The cyclone should be
absorbed by a larger extratropical low, as the cyclone quickly
approaches Ireland and the United Kingdom.

Satellite fixes indicate that Helene is moving toward the
north-northeast or 030 degrees at about 16 kt. Helene is embedded
within the fast southwesterly flow ahead of a sharp mid-level
trough and this pattern should steer the cyclone toward the
northeast with a gradual increase in forward speed. Track guidance
is very consistent with this solution, and the NHC forecast
continues in the middle of the tight guidance envelope.

Helene is expected to be a post-tropical cyclone when it approaches
Ireland and the United Kingdom in a few days.  Interests in those
locations should consult products from their local meteorological
service for information about potential impacts from Helene.  Local
forecasts and warnings for the UK can be found on the website of the
UK Met Office at https://www.metoffice.gov.uk/.  Local forecasts
and warnings for Ireland can be found on the website of Met Eireann
at https://www.met.ie/.

FORECAST POSITIONS AND MAX WINDS

INIT  15/0300Z 35.8N  35.8W   60 KT  70 MPH
 12H  15/1200Z 38.0N  34.5W   60 KT  70 MPH
 24H  16/0000Z 40.3N  31.2W   55 KT  65 MPH
 36H  16/1200Z 42.5N  26.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  17/0000Z 45.0N  21.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 72H  18/0000Z 51.5N   9.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  19/0000Z...DISSIPATED

$$
Forecaster Avila

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