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Tropical Storm Ernesto Discussion Number   8
NWS National Hurricane Center Miami FL       AL052018
1100 PM AST Thu Aug 16 2018

Convection associated with Ernesto has increased in both coverage
and intensity since the last advisory, with a large convective band
wrapping about three-quarters of the way around the system.
However, recent scatterometer data suggests that this has not yet
resulted in strengthening, with winds of 35-40 kt observed about
80 n mi southeast of the center.  Based mainly on the scatterometer
data, the initial intensity remains 40 kt.

While Ernesto is in a warm moist air mass to the east of a
mid-latitude cyclone near Newfoundland, the forecast track quickly
takes it over sea surface temperatures that will decrease to near
15C in 24 h.  This should lead to the dissipation of the convection
and to Ernesto becoming a post-tropical cyclone.  In 36-48 h, the
post-tropical cyclone should merge with a frontal zone, with the
resulting extratropical low dissipating between 48-72 h.  Overall,
the new intensity forecast is nudged slightly downward from the
previous forecast, as the guidance no longer shows significant
strengthening. Given the increased convection, though, some
short-lived strengthening could occur in the next 12 h. In addition,
the current trends have led to the time of Ernesto becoming
post-tropical being moved back 12 h.

The initial motion is now 055/19.  The cyclone should accelerate
further while moving northeastward to east-northeastward within the
mid-latitude westerlies over the next day or two.  The dynamical
model guidance remains tightly clustered and, as with the previous
advisory, little change was made to the track forecast.  On the
forecast track, Ernesto or its remnants should approach Ireland and
the United Kingdom in about 48 h.


FORECAST POSITIONS AND MAX WINDS

INIT  17/0300Z 44.1N  38.9W   40 KT  45 MPH
 12H  17/1200Z 46.1N  34.8W   40 KT  45 MPH
 24H  18/0000Z 48.9N  27.7W   40 KT  45 MPH...POST-TROPICAL
 36H  18/1200Z 51.2N  19.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
 48H  19/0000Z 53.2N  12.1W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  20/0000Z...DISSIPATED

$$
Forecaster Beven

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