Official Discussion issued by the National Hurricane Center

Ernesto (AL052018) DATA RELEASED: 8/15/2018 11:00:00 AM UTC

Copy of official data

Subtropical Storm Ernesto Discussion Number   2
NWS National Hurricane Center Miami FL       AL052018
1100 AM AST Wed Aug 15 2018

Convection associated with the subtropical cyclone became better
organized after the release of the previous advisory, but
cloud tops have warmed recently with the convection becoming
somewhat fragmented.  An Hebert-Potent subtropical classification of
T2.5 from TAFB suggests that they system is producing gale-force
winds, and recent scatterometer data that passed over the far
eastern portion of the circulation revealed 30-kt winds. Since the
instrument missed the radius of maximum winds, it is assumed that
stronger winds exist over the eastern portion of the circulation,
and the initial intensity is increased to 35 kt, making the system
a subtropical storm.

Ernesto has about 24 hours over marginally warm SSTs and in a low-
shear environment in which to strengthen.  After that time, the
cyclone will be moving over much colder water which should cause it
to become post-tropical within 48 hours. The post-tropical cyclone
is forecast to merge with a frontal zone associated with a larger
extratropical cyclone over the North Atlantic in 3 to 4 days.

The cyclone is moving northward at about 6 kt. A mid-level trough
that is moving off the east coast of the United States should cause
Ernesto to turn north-northeastward later today, and the cyclone is
forecast to accelerate northeastward by late Thursday as it becomes
embedded within the mid-latitude westerlies. The dynamical model
guidance continues to be in good agreement, and the new NHC track
forecast remains in the middle of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT  15/1500Z 38.1N  46.0W   35 KT  40 MPH
12H  16/0000Z 39.3N  45.3W   40 KT  45 MPH
24H  16/1200Z 41.3N  43.5W   45 KT  50 MPH
36H  17/0000Z 43.6N  40.3W   45 KT  50 MPH
48H  17/1200Z 46.4N  35.2W   45 KT  50 MPH...POST-TROPICAL
72H  18/1200Z 52.3N  21.0W   40 KT  45 MPH...POST-TROPICAL
96H  19/1200Z...MERGED WITH LARGER EXTRATROPICAL LOW

$$
Forecaster Brown