Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 200812

National Weather Service Jackson KY
412 AM EDT Thu Oct 20 2016

.SHORT TERM...(Today through Friday)
Issued at 355 AM EDT THU OCT 20 2016

Morning surface analysis shows the quasi-stationary boundary
remains NW across the Ohio River. A secondary cold front further
NW of the previously mentioned boundary. The boundary across the
Ohio River region will eventually progress east across eastern KY
this afternoon and evening. In terms of AM POPs did keep slights
ahead of the boundary, as the LLJ kicks in and perhaps a bit of
mid level forcing. These showers are actually showing up across
Middle TN and portions of the Cumberland Plateau on radar this AM.
However the bulk of our rainfall will come from the actual
cold front and upper level wave. Right now we are looking at
around three quarters to one inch of rainfall across the region
through Friday. That said we also remain in a marginal risk for
severe storms today from the SPC. We do have reasonable effective
bulk shear values approaching 40 knots and reasonable instability.
The question is how much instability with 4KM NAM remaining the
more robust in relation to this, and not sure if we will realize
the NAM numbers at this point given potential cloud cover. Overall
CAMs would suggest a broken line will progress across the region
between 21z and 00z. Given that would think the chances for
marginally severe wind gusts are possible with some of these line
segments. Now in terms of temps did come up from model blend
particularly in the south and east for this afternoon where less
cloud cover is possible early.

Tonight the cold front will move out of the region, and POPs will
slowly decrease from west to east toward dawn. The big news will
be the colder airmass, as the base of the upper level trough axis
swings across KY. This and secondary cold front will lead to a 15
to 20 degree drop in temps for Friday, as temperatures struggle
to rise out of the 50s. This all as NW flow aloft leads to cloud
cover and 850mb CAA continues to work in with temps in the 0 to 2
C range from NW to SE by the afternoon.

.LONG TERM...(Friday night through Wednesday)
Issued at 412 AM EDT THU OCT 20 2016

The models remain in general agreement with an amplified long wave
pattern to control across the CONUS this weekend into early next
week. Deep troughing will become established across the eastern
Pacific, with ridging across the Plains and into the Midwest.
Meanwhile, another trough will pull towards the eastern Seaboard,
and eventually wrap up into an upper level low across eastern
Canada. Towards the end of the period, the flow looks to flatten
out somewhat, as the troughs relax in the west and east.

Eastern Kentucky will start out under the influence of a trough,
with a few showers likely lingering into Friday evening, before
ending from west to east. A much cooler air mass will funnel in on
northwest winds by Saturday morning. Some 30s are expected in the
higher elevations in the southeast, as well as locations west of
I-75, which will stand the better chance of partial clearing.

Saturday will be the coolest daytime highs we have seen since May,
as readings will only climb into the mid to upper 50s. This will
set the stage for more widespread 30s for the valleys by Sunday
morning, as skies clear out and high pressure skirts by to our
south. Heights will rebound quickly for the second half of the
weekend, with gusty southwest winds helping to rebound highs 10
degrees or more on Sunday.

Early next week, a cold front looks to move through by early
Monday, with little consequence besides a slight increase in
clouds and a wind shift. Dry weather will hold on into the middle
of next week, before another cold front takes aim at the area
towards Thursday. Temperatures will be seasonable, with lows in
the 40s, and highs in the upper 60s to lower 70s.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)

VFR conditions are the story for the beginning of the period, but
we will see decreasing VIS and Lowering CIGs late in the period.
Cold front remains north of the region this hour and this will be
the story through the night. There is a mid level wave and 850 mb
jet that could induce a few showers toward dawn, and these
showers are showing up on radar down in portions of TN this hour.
However kept the POPs in the slight range at this point and
generally do not introduce VCSH till 12z to 14z. By Thursday
afternoon we will see chances for rain on the increase and the
potential for Thunderstorms. A few of these storms could be strong
and lead to gusty winds. Generally TAF sites will see fluctuations
from MVFR to LIFR depending on the strength of the storms that
happen to hit a site. Overall the first part of the period winds
will remain light, but increased wind gusts are possible through
the afternoon.




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