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000 
FXUS63 KJKL 130825
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
325 AM EST Fri Dec 13 2019

.SHORT TERM...(Today through Saturday)
Issued at 325 AM EST FRI DEC 13 2019

08z sfc analysis shows a strong area of high pressure northeast 
of the Appalachians with its backside wind flow pushing moisture 
along the spine of the mountain range. This moisture is pouring 
over the crest and into eastern Kentucky. Earlier in the evening 
the clouds associated with this were higher and thinner allowing
for radiational cooling that sent many of the sheltered valleys 
into the upper 20s by midnight. However, the lower clouds 
associated with the initial band of rain has mostly mixed out the 
colder spots now so that all observations are at or above freezing
and likely removing the threat for freezing rain. Although all 
indications are that this is the case, will continue the pre- 
first period mention of this possibility and the SPS to err on the
side of caution early this morning. Otherwise, temperatures 
across the area vary from right at freezing at the Paintsville 
mesonet site to the lower 40s in the Cumberland Valley. Dewpoints,
meanwhile have come up to the low 30s most places, but some 20s 
remain in the northern parts of the area. Winds, are generally 
light and variable under overcast skies. 

The models are in good agreement aloft through the short term
portion of the forecast. They all depict a lead shortwave moving
through the area this morning ahead of a broader trough
approaching from the west. This trough will be deepening and
sharpening up as crosses the Mississippi River and moves into the
Deep South later this evening. This open trough then bodily lifts
northeast through the Southern Appalachians on Saturday in tandem
with a sharp trough passing by the Great Lakes in the northern 
stream. Given this overall model agreement have favored a blended 
solution as reflected in the NBM with little in the way of wide- 
scale adjustments needed. 

Sensible weather will see the freezing rain threat end with sunup
this morning followed by continued damp conditions as low pressure
runs up the East Coast later today and tonight. At the same time
another area of low pressure will approach Kentucky from the west
prolonging the moisture over the JKL CWA basically through the
period. However, there will not be all that much lift over the
area for much of the time limiting the actual QPF despite the high
PoPs. There will be a bit of a lull to the more substantial rains
this morning into the afternoon with better lift coming into play
tonight into Saturday morning. The moisture does move on east 
effectively by later Saturday finally allowing for some drying. 
Much of the time temperatures will be not far from cold enough for
snow, but only at the highest elevations will there be an actual 
chance of it mixing in - basically above 3000 feet and mainly 
Saturday morning. Will make a small mention of this in the HWO for
our highest terrain. 

Generally used the NBM as the starting point for all the grids
with only small adjustments to the temperatures through the 
period. As for PoPs and QPF, primarily adjusted them to limit the
extremes in the near term, but also to hit the higher terrain and
east a bit harder tonight and Saturday. 

.LONG TERM...(Saturday night through Thursday)
Issued at 320 AM EST FRI DEC 13 2019

The extended forecast is complicated with a good deal of uncertainty 
involving how much snow we may see across the area Sunday night into 
Monday morning. The diurnal behavior of hourly temperatures during 
that same time frame is also a bit up in the air. The model data are 
not handling hourly temperatures so well, so did the best job we 
could concocting hourly temps Sunday night and Monday. In general, 
we should see on weather system, and its associated rain and snow, 
exiting the area Saturday night. After a brief period of dry weather 
Sunday morning into early Sunday afternoon, we should see another 
bout of precipitation moving in from the south and southwest, as a 
warm front moves through the area. Precipitation north of the front 
should be in the form of snow or a rain/snow mix, as colder air 
settles over that area. Rain will be on tap south of the warm front 
on Monday, and we may even see a few rumbles of thunder, as warm 
moist and slightly unstable air surges northward ahead of an 
approaching cold front. Any storms that form should quickly 
dissipate early Monday evening, as instability dies down. A bit of 
snow may mix with rain Monday night into early Tuesday morning, as 
colder air filters into eastern Kentucky behind the departing cold 
front. Any snow accumulations we might see in the extended would 
likely occur Sunday night into early Monday morning, and north of 
the Mountain Parkway.

Daily highs should be mainly in the 40s during the period. The first 
exception will be Monday, when we could see highs in the 50s for 
most locations and near 60 along the TN border. The other exception 
would be Wednesday, when steady westerly flow will bring colder air 
into the area, yielding highs in the 30s across the area. Nightly 
lows will be in the 20s and 30s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1250 AM EST FRI DEC 13 2019

We are starting off the period under VFR skies, barely, as mid
level and lower clouds stream into the region early this morning. 
An upper level wave is providing enough lift to bring in some 
light rain late tonight and further lower CIGs into the MVFR 
range through the late night hours into dawn. These CIGs will 
probably stay in the MVFR range from dawn into the afternoon.
However, another slug of precipitation will progress into the 
area late in the period and bring lowering CIGs into the IFR 
range and VIS into the MVFR range by late Friday afternoon. The 
winds will remain light through the TAF period at around 5 knots 
or less and variable in direction.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

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