Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 141731

National Weather Service Jackson KY
131 PM EDT Wed Mar 14 2018

Issued at 1217 PM EDT WED MAR 14 2018

Flurries and a few snow showers continue to affect eastern
Kentucky. With extensive cloud cover temperatures have been slow
to rise. Have updated sky condition for more cloud cover this
afternoon, mainly across the northeast three quarters of the
forecast area, and have lowered afternoon temperatures for many

UPDATE Issued at 1014 AM EDT WED MAR 14 2018

Radar shows isolated snow showers and flurries continuing in the
southeast part of the area, and there are also some returns over
southwest OH and far northern KY. Have updated NDFD to slow the
exit of snow showers in the southeast and to add flurries across
much of the eastern part of the forecast area. Snow showers have
been declining in the southeast so have allowed the winter
weather advisory to expire.

UPDATE Issued at 730 AM EDT WED MAR 14 2018

Issued an update to the forecast to input the latest observations
and trend them through the morning hours. Adjusted the pops lower
as the last of the snow showers have tracked further southeast
into eastern Kentucky. Some of the snow showers have produced
squall like conditions with a quick inch of snowfall put on the
ground. Most of the showers have moves southeast so have expired
another layer of the Winter Weather Advisory. The far east and
southeast will remain in effect through 9am.


.SHORT TERM...(Today through Thursday)
Issued at 333 AM EDT WED MAR 14 2018

Current conditions across the area feature the last of a wave
swing southeast through eastern Kentucky as the parent upper low
slowly exits to the northeast over the Northeast CONUS. Northwest
winds continue across the area heading into the dawn hours. This
will keep the presence of snow showers across the area through the
post dawn hours. With a rapid decrease of moisture, will be
losing the moisture depth and thus the snow shower threat will be
ending by mid morning. The accumulating snow over the western CWA
will be coming to an end and thus will be ending the WSW at least
for a portion of eastern Kentucky. In fact, dry air following in
behind this impulse will drop dew points for the day today into
the teens. Highs will struggle to get out of the 30s today will
the colder air filtering into the region, even despite the
clearing skies.

Clear skies to begin this evening will allow valley temps to
plummet into the 20s at least for the first part of tonight. The
last piece of moisture dropping south from the exiting upper low
will bring a brief period of cloud cover to mainly eastern
portions of the area. This will slow the ridge to valley
temperature difference. The last of the upper low will lift to the
northeast for the day on Thursday allowing high pressure and
clearing skies to dominate the weather. This will allow
temperatures to rebound to near 60 in some areas.

.LONG TERM...(Thursday night through Tuesday)
Issued at 515 AM EDT WED MAR 14 2018

The models aloft are at least slightly out of step with each
other through the bulk of the long term portion of the forecast.
In particular, an increasing spread between the GFS and ECMWF is
worrisome and significantly hampering confidence in any single
model solution. They generally depict a weakening, but once closed
off, trough riding east into the Ohio Valley this weekend
following a brief visit of some higher heights. Even with the
patch of ridging ahead of the trough - energy manages to move
through Kentucky unhindered. However, it is this dampening trough
that brings the troublesome weather with it for Friday night and
Saturday as its energy is strung out through the state. This wave
is sharper and slightly faster in the ECMWF while the GFS starts
to lift heights much quicker in its wake late Saturday. Later in
the weekend the models sync up better locally, but remain distinct
from each with the next trough formation over the central and
northern Rockies. After a brief visit from a flat ridge this
fairly progressive trough will then head into the Ohio Valley for
later Monday and Tuesday. The ECMWF has a much stronger lead wave
with this than the GFS magnifying the differences. Accordingly,
confidence is low in either specific solution. Given these
discrepancies the general model blend was favored, though
allowances were needed for more realistic temperatures (and
dewpoints) Friday night into Saturday morning where the raw blend
was used in place of the more complete SuperBlend.

Sensible weather will feature a complicated and, typical of this
transition season, changeable situation through the weekend. Into
the cold air in place, a developing warm front will lay out
through southeastern Kentucky Thursday night into Friday with
showers arriving by dawn in the southern half of the CWA. The
northern fringe of this could mix with snow showers, as well. The
boundary will stay in place making for a wet day on Friday with
the colder air still butting up against it to the northeast. As
such, later that night additional precipitation will come down
with a potential for light freezing rain or sleet as well as the
rain to our northern counties - given a warm surge aloft but not
much movement to the cold air at the sfc. Accordingly, have
introduced this potential to the forecast and highlighted it as a
concern in the HWO. Warm air then more effectively moves into
eastern Kentucky from the southwest later Saturday into Sunday
with showers a good bet as weak low pressure passes through the
area. Weak high pressure nosing in from the north on Sunday
afternoon and into Monday will only temporarily dry us out for a
time. However, the next weather maker will quickly take shape to
the west and potentially become strong over the Mid Mississippi
Valley late Monday. This will place eastern Kentucky in the
system`s warm sector with even a potential for a thunderstorm
Monday night into Tuesday. Due to the fluidity of this situation
and model disagreement have held off on including thunder in the
forecast at this time. Colder weather follows later Tuesday as the
sfc low passes by to the northeast - with more pcpn possible. The
question is how much colder - with the ECMWF relatively mild
compared to the GFS.

Did not make much more than spot temperature adjustments to the
Superblend - aside from the use of the raw blend Friday night into
Saturday morning. Also, only made some tweaks to PoPs to try and
hone in on the better times and threats of measurable pcpn like
from Friday night through Saturday and again Monday night into


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)

Northwest flow across the area continues to bring widespread
clouds to all but the far southwest part of the forecast area.
Ceilings were gradually lifting, but MVFR ceilings will persist
in the eastern part of the forecast area through the afternoon.
Scattered flurries and isolated snow showers have persisted,
resulting in very local visibility restrictions as well. Flurries
will end and clouds will continue to lift and decrease in
coverage, with VFR conditions expected overnight and into
Thursday. Late tonight and into early Thursday low level wind
shear is expected to develop.




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