Area Forecast Discussion
Issued by NWS Jackson, KY

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KJKL 141916

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

.SHORT TERM...(This evening through Thursday night)
Issued at 316 PM EDT WED MAR 14 2018

Northwest flow has kept clouds and flurries over the eastern part
of the forecast area through the afternoon, but flurries will
finally end by early this evening. The overnight forecast
challenge is the low temperature forecast. Based on current
observed temperatures, at least a temporary break in cloud cover
for part of the night, and snow on the ground in some areas,
overnight lows will likely be lower than the blended guidance and
also the MOS guidance for the main ASOS sites. Some COOP MOS
guidance indicates lows in the teens, but that seems too cold.
Warm advection does set in overnight, and how long a break in
cloudiness occurs is uncertain. Have gone with lows mainly in the
25 to 30 degree range, but this will need to be monitored this
evening and likely adjusted.

With abundant mid March sunshine forecast for Thursday
temperatures will climb into the 50s in most areas, with highs
ranging from lower 50s north and east to upper 50s southwest.
A dry cold front will pass through the area Thursday before
stalling in the TN Valley Thursday night. Some overrunning
precipitation may develop north of this front over southern parts
of the forecast area by daybreak Thursday. Thursday night lows
should range from the mid 20s in the northern part of the forecast
area to the mid 30s in the south. If precipitation does develop, thermal
profiles support the idea of the possibility of a narrow ribbon
of very light snow or sleet on the northern edge of the
precipitation at the onset.

.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.




AVIATION...SBH is the U.S. government's official web portal to all federal, state and local government web resources and services.