Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 170054
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
754 PM EST Tue Jan 16 2018

.UPDATE...
Issued at 754 PM EST TUE JAN 16 2018

The latest WSR-88D scans show the main area of light to moderate
snow continues to exit southeast this evening. We did keep Winter
Weather Advisory going a little longer at some of the far
southeast counties given the radar trends. Otherwise flurries and
perhaps a few snow showers were seen in the wake of the main band
of precip associated with the 850mb front.

The latest GOES-16 water vapor imagery shows a positively tilted
trough still extends from the lower Great Lakes into the Central
Plains this evening. This trough will slowly progress eastward
tonight and some clouds are coming into portions of central and
western Kentucky as it moves east. The cloud cover forecast has
been tricky this evening, with snow showers and the main cloud
deck mentioned above. In contrast, some areas have seen clearing
skies and temperatures have consequently plummeted into the single
digits or lower in those spots. Overall think the temperatures
will level off some eventually, but all spots will see at least
single digits overnight. Given this and the potential for snow
showers did opt to hoist a SPS for the area to handle these
issues. In term of hourly temperatures tried to use obs and slowly
blend into the current trend. These will likely have to be
further fine tuned in subsequent updates. Grids have been updated
with thinking and sent to NDFD.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 355 PM EST TUE JAN 16 2018

A positively tilted trough is currently aligned from eastern
Canada down to northern Mexico. This feature is slowly working its
way east. A lingering upper level jet, lending sustained deeper
lift, has brought widespread moderate to heavy snow to eastern
Kentucky through the day. So far, totals have ranged from about an
inch across our far southeast, with 2 to 5 inches elsewhere. The
back edge of the snow is moving through the I-64 corridor, and
this will gradually work off to the southeast through this
evening.

Some partial clearing may work in temporarily tonight, before the
trough axis moves in, allowing for a return of clouds and a few
snow showers. Temperatures will drop into the single digits for
lows. On Wednesday, isolated snow showers and flurries will
diminish generally from west to east through the day, with highs
only at around 20.

The center of a surface high pressure will build in closer to us
Wednesday night, especially in the southern portion of our area.
This will allow for a cold night, with temperatures likely
dropping down to near zero or lower in places, given the lingering
snow pack and clearing skies.

.LONG TERM...(Thursday through Tuesday)
Issued at 355 PM EST TUE JAN 16 2018

The overall pattern for the long term shows a distinct separation
between the northern stream over the Great Lakes and the southern
stream over the Mississippi Valley. This will lead to more zonal
flow evolving to ridging for eastern KY through the weekend before a
disturbance moves through early next week. The models seem to be
in decently good agreement with the overall pattern, but differ in
timing and intensity of the cold front next Monday. The ECMWF
shows a slightly faster and more intense band of precip as
compared with the GFS. Therefore, the uncertainty for precip
totals and timing into the CWA is high.

Looking closer to the surface, high pressure will set up to the
SW of eastern KY for the beginning of the extended period. The
high will gradually shift to the east and be to our SE by the
weekend. This will bring in SW to S winds, and this combined with
minimal cloud cover, will increase the potential for ridge/valley
temperature splits Thursday and Friday night. This also means WAA
into the region over the weekend leading to warmer high temps in
the 50s and 60s. With such high temps, the precip brought in by
the cold front Monday will likely be rain showers. The passage of
the cold front will usher in cooler temps, with precip possibly
ending as a mix of rain/snow on the higher elevations.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 639 PM EST TUE JAN 16 2018

VIS and CIG conditions are improving quickly across eastern
Kentucky this evening. Most sites have improved to VFR with the
lone lower sites being SJS/SYM. There is an area of of mostly
clear skies that will move across the area in the wake of the snow
band. Then additional clouds will fill in from the northwest
later this evening, but these are expected to remain in the VFR
category at this time. There could also be some light snow
showers or flurries tonight into early wednesday, so kept a VCSH
going in the TAFs to handle this for now. Winds will remain light
out of the west and northwest through the period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight EST tonight for KYZ088-
118-120.

&&

$$

UPDATE...DJ
SHORT TERM...GEOGERIAN
LONG TERM...CGAL
AVIATION...DJ



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