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Tropical Storm Ernesto Discussion Number  12
NWS National Hurricane Center Miami FL       AL052018
1100 PM AST Fri Aug 17 2018

Organized deep convection associated with Ernesto has dissipated
after the issuance of the last advisory. If it does not return,
which seems unlikely with the system moving over SSTs of 16C or
less, Ernesto should become a post-tropical cyclone by early
Saturday.

Geostationary and microwave imagery along with ASCAT data indicate
that the mid-level circulation has begun to separate from the
low-level center. A partial ASCAT-A pass from 2148 UTC showed a
large area of 35-40 kt winds south and southeast of the center, and
on that basis the initial intensity remains 40 kt. Ernesto is
forecast to weaken only a little during the next 24 hours while it
approaches Ireland and merges with a frontal zone Saturday night.
The post-tropical cyclone's circulation should dissipate while it
moves across Ireland and portions of the United Kingdom by early
Sunday.

Ernesto is racing east-northeastward at 30 kt and this motion
should continue until dissipation. The new NHC forecast is close to
the previous one and lies near the middle of the tightly clustered
guidance envelope.

The post-tropical cyclone or its remnants are expected to spread
gusty winds and locally heavy rain over portions of Ireland and the
United Kingdom Saturday night and early Sunday. Information on
rainfall and wind forecasts for Ireland can be found in products
issued by Met Eireann at www.met.ie and for the United Kingdom in
products issued by the United Kingdom Met Office at
www.metoffice.gov/uk.

FORECAST POSITIONS AND MAX WINDS

INIT  18/0300Z 50.4N  25.6W   40 KT  45 MPH
 12H  18/1200Z 52.3N  18.8W   40 KT  45 MPH...POST-TROPICAL
 24H  19/0000Z 54.1N  10.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 36H  19/1200Z...DISSIPATED

$$
Forecaster Brennan

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