Official Discussion issued by the National Hurricane Center

Epsilon (AL272020) DATA RELEASED: 10/20/2020 9:00:00 AM UTC

Copy of official data

Tropical Storm Epsilon Discussion Number   5
NWS National Hurricane Center Miami FL       AL272020
500 AM AST Tue Oct 20 2020

Epsilon continues to have a non-standard appearance in satellite
imagery this morning.  While an area of convection is near and over
the center, the center is also near the western end of a baroclinic
zone, and that is giving the storm the look of a occluded
extratropical low.  In addition, water vapor and air mass imagery
indicate that an upper-level trough is close to the system in the
southwestern semicircle.  Satellite intensity estimates have not
changed significantly since the last advisory, so the initial
intensity is unchanged at  40 kt.  Epsilon remains a large cyclone
with gale-force or tropical-storm-force winds extending outward
more than 250 nmi in the northern semicircle.

The center has drifted eastward since the last advisory, with the
initial motion a somewhat uncertain 075/3.  A northward to
northwestward motion is expected to begin shortly as Epsilon
becomes embedded in a large mid-level low over the central
Atlantic.  Later today, a mid-level ridge is forecast to build to
the north and east of the cyclone, forcing Epsilon generally toward
the northwest through about 72 h.  After that time, a deep-layer
trough and associated frontal system moving eastward into the
western Atlantic should cause the cyclone to recurve to the
northeast at an increasing forward speed.  The guidance is in good
agreement with the scenario, and the new forecast track, which has
only minor adjustments from the previous track, lies near the
various consensus models.  On the forecast track, Epsilon should
make its closest approach to Bermuda on Friday.

There are several conflicting factors in the intensity forecast.
First, while the cyclone is expected to move over relatively warm
sea surface temperatures, the oceanic heat content along the
forecast track drops to low levels after 36 h.  Second, while the
overall shear is forecast to be light to moderate through the
forecast period, Epsilon is interacting with the aforementioned
upper-level trough, and the global models suggest it will interact
with another trough around the 72 h point.  These troughs should
provide upper-level divergence to aid strengthening, but also may
feed cool and dry air into the cyclone, which would be a negative
factor.  The intensity guidance continues to show gradual
strengthening despite the negative factors, with the global models
showing fairy low central pressures during the 72-120 h period.
Based on this, the intensity forecast continues to call for Epsilon
to become a hurricane, and the new forecast has only minor tweaks
from the previous forecast.  Extratropical transition will likely
be underway by 120 h, but likely will not finish until after the
end of the forecast period.

Key Message:

1. Epsilon is forecast to be at or near hurricane strength when
it approaches Bermuda late this week.  While it is too soon to
determine the exact details of Epsilon's track and intensity near
the island, there is a risk of direct impacts from wind, rainfall,
and storm surge on Bermuda, and interests there should closely
monitor the progress of Epsilon.


INIT  20/0900Z 25.6N  54.7W   40 KT  45 MPH
12H  20/1800Z 26.6N  55.6W   45 KT  50 MPH
24H  21/0600Z 27.8N  57.4W   50 KT  60 MPH
36H  21/1800Z 28.5N  59.1W   55 KT  65 MPH
48H  22/0600Z 29.4N  60.1W   60 KT  70 MPH
60H  22/1800Z 30.6N  60.9W   65 KT  75 MPH
72H  23/0600Z 31.6N  61.4W   70 KT  80 MPH
96H  24/0600Z 33.5N  62.0W   75 KT  85 MPH
120H  25/0600Z 38.0N  58.0W   70 KT  80 MPH

Forecaster Beven