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Subtropical Storm Ernesto Discussion Number   3
NWS National Hurricane Center Miami FL       AL052018
500 PM AST Wed Aug 15 2018

Recent visible satellite imagery has shown a slight increase in
convection near and to the east of the center of Ernesto this
afternoon, but there has been little change in the overall
organization of the subtropical storm.  The satellite intensity
estimate from TAFB remains an ST2.5, so the initial wind speed
remains 35 kt for this advisory.  Ernesto is forecast to remain over
marginally warm SSTs and in a low wind shear environment during the
next 12-24 hours, and some modest strengthening is anticipated.
After that time, the cyclone will be moving over SSTs below 20C and
into an area of increasing vertical wind shear.  As a result,
Ernesto is forecast to become a post-tropical cyclone in about 36
hours, and merge with a frontal zone near Ireland and the United
Kingdom in 3 to 4 days.

Ernesto is moving northward or 005/8 kt.  The cyclone should turn
north-northeastward tonight ahead of a mid-level trough that is
located off the coast of the eastern United States. Ernesto is
forecast to become embedded within the mid-latitude westerlies by
late Thursday and it is expected to accelerate northeastward at
that time. The track guidance remains in good agreement, and the
NHC forecast is again near the center of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT  15/2100Z 39.0N  45.7W   35 KT  40 MPH
 12H  16/0600Z 40.4N  44.6W   40 KT  45 MPH
 24H  16/1800Z 42.6N  42.1W   45 KT  50 MPH
 36H  17/0600Z 45.1N  37.9W   45 KT  50 MPH...POST-TROPICAL
 48H  17/1800Z 48.0N  31.8W   45 KT  50 MPH...POST-TROPICAL
 72H  18/1800Z 53.0N  15.8W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  19/1800Z...MERGED WITH FRONTAL ZONE

$$
Forecaster Brown

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