Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 181643
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1143 AM EST Thu Jan 18 2018

.UPDATE...
Issued at 920 AM EST THU JAN 18 2018

Updated the forecast to input the latest observations and trend
them into the morning hours across the area. Most temperatures
have now warmed above zero by now. Some of the more sheltered
eastern valleys are still hanging around zero. A new zfp was not
needed for this update.

UPDATE Issued at 735 AM EST THU JAN 18 2018

Hourly sky cover and hourly temperature grids have been updated
based on observation and satellite trends. No other changes were
needed at this time. Despite the cold start, temperatures will
begin to moderate to start today.

&&

.SHORT TERM...(Today through Friday)
Issued at 305 AM EST THU JAN 18 2018

The axis of an upper level trough extending from Quebec to the
Southeast Conus continues to move east of the area with surface
and upper level ridging building into the region. Stratocu and
flurries linger near the VA border and in the vicinity of Lake
Cumberland where a westerly fetch across the lake appears to have
lead to clouds forming east of the Lake likely from steam over the
lake. Temperatures vary generally in the single digits through
some valley locations that have remained clear are in the single
digits below zero.

Surface high pressure over the Southeast Conus and centered over
the Lower MS Valley will build into the region today with mid
level heights rises through at least the middle part of the day
before remaining generally steady as a shortwave trough works into
the Great Lakes region. Warm advection will begin aloft today,
with 850 mb temperatures initially about 3 to 8 below warming to
around 0C by this evening. However, despite this warm advection
and abundant sunshine the snowpack currently in the about 1 to 4
inch range will likely suppress temperatures to below MOS guidance
numbers. The superblend guidance of low to mid 30s appeared
reasonable and did not stray far though given the cold start it is
possible temperatures even fall short of these numbers.

The snowcover should factor into the picture again tonight with
high pressure and light winds. For this cycle, undercutting the
superblend guidance numbers for valley locations was continued,
trending toward the colder coop mos numbers.

Further height rises will continue through the end of the period
with further warm advection with sfc high pressure still in
control. 850 mb temperatures should warm to around 3C by the end
of the period. Temperatures should moderate further into the low
to mid 40s for most locations or near climatological normals.

.LONG TERM...(Friday night through Wednesday)
Issued at 240 AM EST THU JAN 18 2018

Zonal flow will set up in the mid levels as we head into the
upcoming weekend, with a nice warm up anticipated. We will could
see cold conditions Friday night with snow lingering on the ground
with a decent chance to go lower than guidance. This could put our
valley locations into the teens Friday night. As southerly flow
takes hold Saturday, temperatures will get a boost into the 40s.
Isentropic ascent will develop as we head into Saturday night and
Sunday and could yield some drizzle across the northwestern third
of the forecast area, mainly impacting our bluegrass counties and
perhaps areas north of I-64. With the low level flow not really
downsloping across our area, we could see a little more coverage
in the drizzle. Regardless, probably not a whole lot of sunshine
come Sunday. By Sunday night, shortwave ridging will develop as a
strong cold front pushes across the central plains. This front
will be associated with a strong area of low pressure tracking
across the great lakes early next week. As this happens, this cold
front will track across the area, providing a period of showers.
Still some slight differences in timing on the models, but looks
like Monday afternoon and Monday evening is when rain chances will
peak. Conditions dry out through the rest of the forecast period
as high pressure builds back into the region. While it will turn
cooler behind the front Monday night into Tuesday, it looks like
temperatures should remain more around seasonable values for mid
to late January.  with highs in the 40s and lows in the 20s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1143 AM EST THU JAN 18 2018

High pressure has settled through the area with clear skies
expected through the TAF period. Thus VFR conditions are expected
throughout the TAF period. Wind will generally by from the
southwest today from 5 to 10 knots before becoming light and
variable after 00Z.

&&

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

$$

UPDATE...SHALLENBERGER
SHORT TERM...JP
LONG TERM...KAS
AVIATION...SHALLENBERGER



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