Area Forecast Discussion

FXUS63 KJKL 150614 AAA
National Weather Service Jackson KY
114 AM EST Fri Dec 15 2017
Issued at 114 AM EST FRI DEC 15 2017
Have freshened up the hourly temperature and dew point trends 
through the overnight, otherwise the forecast generally remains on
UPDATE Issued at 1046 PM EST THU DEC 14 2017
The low clouds look to hang tough overall through the night, as
the latest short term model guidance shows plentiful moisture in 
the 925-850mb layer pivoting back in across eastern Kentucky. 
There are some spots that have seen clearing, mainly on the 
northwest and southeast fringes of the deck. Have adjusted lows 
accordingly, keeping mainly upper 20s to around 30 degrees for
locations where the clouds will not relent, while allowing for 
some low to mid 20s in the cooler spots. Updates will be out
UPDATE Issued at 723 PM EST THU DEC 14 2017
Latest GOES-16 imagery continues to show quite a bit of cloud
cover holding across much of eastern Kentucky. NAM Bufkit
soundings show this moisture quite well and actually show some
redevelopment through the overnight hours. A subtle shortwave will
also push in late tonight with some low level cooling noted. This
may be enough to bring the top of the moist layer into the -10 to
-12C isotherm allowing for some ice introduction into the clouds.
 This combined with a light west wind develop towards daybreak, 
 may provide a bit of upslope into the higher terrain. All of this
 together points towards a good potential for some flurries or 
 very light snow showers. Opted to keep precipitation non- 
 measurable at this point, but some of the higher peaks in 
 southeast Kentucky could see a light dusting by daybreak Friday. 
.SHORT TERM...(This evening through Friday night)
Issued at 357 PM EST THU DEC 14 2017
Low stratus has held strong across eastern Kentucky this afternoon 
in a post-frontal airmass. Temperatures have subsequently held 
steady with current readings spanning the 30s. Surface ridging 
building into the lower Ohio Valley and western reaches of the 
Appalachians will keep light upslope flow in place through much of 
the night as low-mid level moisture remains trapped beneath a 
subsidence inversion. Have therefore warmed overnight low 
temperatures a few degrees from the previous forecast given the 
greater amount of expected cloud cover. Readings should generally 
bottom out in the low-mid 20s, with perhaps a few valleys across 
portions of northeast Kentucky flirting with the 20 degree mark if 
any breaks in the clouds can occur nearer the core of the surface 
Yet another upper trough and associated surface low will rotate 
through the Great Lakes Friday, keeping below normal temperatures in 
the offing. Highs look to warm into the mid 30s, resulting in a 
similar overall feel to Thursday afternoon. The lack of any bonafide 
moisture recovery and northward displacement of the greatest forcing 
will negate the threat for precipitation throughout eastern 
Kentucky. Surface ridging nosing in from the southwest later in the 
day will keep winds southwesterly and preclude a significant change 
in airmass.
Following what may be a quick valley dropoff in temperatures Friday 
evening/early night, an increasing pressure gradient downstream 
of a surface low pushing into the upper Midwest will promote warm 
air advection spilling into the Bluegrass and Lake Cumberland 
regions. Temperatures by daybreak Saturday should therefore bottom
out a few degrees warmer than those seen Friday morning.
.LONG TERM...(Saturday through Thursday)
Issued at 322 PM EST THU DEC 14 2017
The extended portion of the forecast begins on Saturday with the 
upper level pattern transitioning to a more progressive and less 
amplified flow aloft. With a brief bout of ridging quickly passing 
through on Saturday. In fact, with southerly flow reengaging on
Saturday, high temps will rebound into the 50s with clear skies in
place thanks to the mentioned ridging in place. The pattern east 
of the Front Range displays a northern and southern portion of the
jet stream and rather zonal. However, a strong wave over the 
southern stream develops over the southwest and moves into the 
lower MS Valley into Saturday night. This feature then lifts 
northeast into the OH Valley for Sunday morning and into the day 
on Sunday bringing a modest round of moisture. Another weaker 
wave tracks across the northern stream into the Great Lakes at 
this time as well. This will keep a decent round of precip over 
the area for Sunday and Monday. Concerning the Sunday morning 
onset, model profiles indicate the possibility of the lower 
profile wet bulbing due to evaporative cooling to freezing 
temperatures at the surface leading to a possibility of a sleet 
and or snow mix for a very brief period of time. However, latest 
trends have showed a later arrival time of precip, this combined 
with the time needed for the lower levels to saturate, will 
likely lead to an all rain event at this time with a few instances
of snow mixed in. Rainfall, while still entering this event with 
dry conditions will accumulated roughly less than a quarter inch.
After passage, another weaker wave along the northern stream will
pass through the OH Valley on Monday with a slight chance of
precip remaining into Monday night. Even so, temps will be above
normal for this time with the lack of amplitude in the pattern and
will only expect liquid precip. By Tuesday, another wave develops
out of the southern stream and lifts northeast bringing another
chance of precip into eastern Kentucky but with warmer air in
place, this event too will be all rain. Despite some rain expected
for Sunday through Tuesday, the lack of consistency in the models
leaves more to be desired and the overall dry conditions across
the area going into these events will be good chance pops at best.
In fact, the super blend cam in dry for the last day of the
extended on Wednesday so will go with that solution. 
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
A stratocu deck will expand and gradually lower down to MVFR
levels across the area through around dawn. This deck will then 
raise up and dissipate by the mid to late morning hours, with VFR 
conditions prevailing thereafter. Light and variable winds through
the late morning, will become westerly at 5 to 10 kts, with some 
gusts of 15 to 20 kts at times, in the afternoon.