Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 030856
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
356 AM EST Sat Dec 3 2016

.SHORT TERM...(Today through Sunday)
Issued at 356 AM EST SAT DEC 3 2016

Surface high pressure will continue to overspread the state
throughout the day today, passing just to our east by 6Z tonight.
Overall this will result in light winds at the surface with llvl
stratus clouds continuing to pull into the region from the NE
through at least mid day in many locations. Llvl winds will begin to
lighten and become more variable as the center of the high passes to
our north and then heads east, allowing the llvl clouds to begin
breaking up throughout the afternoon. Meanwhile, aloft, a shortwave
will begin digging across the northern plains throughout the day,
shifting eastward. This shortwave is expected to reach the
Mississippi River Valley by Sunday, then move across the Ohio River
Valley and points to the north by 0Z Monday.

The upper level wind pattern will feature a jet streak across the
Ohio River Valley ahead of the shortwave, increasing in strength as
the shortwave nears. Mid/upper level winds will be westerly across
KY and then SW just to our east. This will effectively pull moisture
from the Gulf of Mexico northward and then eastward into the state.
As such, this will result in high clouds expected to push northward
into the CWA by later this afternoon. Moisture and clouds will
continue to build this evening with the nearing mid/upper level
wave, however it will have a hard time overcoming the bubble of dry
air at the surface with the surface high pressure center still in
place just to our east. Latest forecast soundings show moisture
finally overcoming the drier air between 6 and 9Z at KSME and KLOZ
in our southern CWA, between 6 and 12Z in the mid sections, and a
few hours later in the northern CWA.

Despite W to SW flow aloft, temperatures in the mid and upper levels
will still be on the cooler side as precip moves into the region
overnight Saturday, below freezing through much of the column. As
such, even as temperatures at the surface may be at or above
freezing at precip onset, rain may still mix with snow for the first
couple of hours. However, temperatures will quickly warm as we head
into the daytime hours, with the surface high continuing eastward
and allowing warmer return flow at the surface.  All precip will
change over to rain during this time, with generally no snow
accumulation or impacts expected. Rain is expected to continue
through the day Sunday as the mid/upper level shortwave closes in on
the region. This will produce generally between 0.10 and 0.20 inches
or rain across the CWA, an overall light system but much needed none
the less.

.LONG TERM...(Sunday through Friday)
Issued at 309 PM EST FRI DEC 2 2016

Active weather is store during the extended period, as a series of
weather systems are poised to bring multiple rounds of precipitation
to eastern Kentucky. The first round of precip is expected Sunday
and Sunday night, as two phased areas of low pressure aloft move
across the region. One system is expected to move across the
northern CONUS, while a second area of low pressure is still
forecast to traverse the Gulf Coast. The area between these two
weather systems is where our precipitation will come from to end the
weekend and kick off the upcoming work week. Some locations north of
the Hal Rogers Parkway may see a few snow flakes mixing with the
rain early Sunday morning, but the latest model data is suggesting
that most precipitation will be in the form of rain Sunday. The best
chance for precipitation looks to be Sunday afternoon and evening,
as the southern stream system moves by to our south, bringing Gulf
of Mexico moisture into the area. This initial round of
precipitation should be coming to and end early Monday morning, as
the causative weather systems move off to our east. After a brief
respite, a second more potent area of low pressure is expected to
move toward the area out of the southern Plains Monday afternoon and
night. This system will be more intense and have more moisture with
it than the first one. In fact, widespread soaking rainfall is
expected across all of eastern Kentucky Monday night and Tuesday.
Energy and moisture from this system will allow for isolated to
scattered rain showers to linger across the area through Wednesday
afternoon.

There will be another lull in the weather Wednesday afternoon and
evening, as a weak ridge of high pressure briefly settles over the
region. A third and final weather system is then expected to move
quickly out of the northern Plains and across the Great Lakes and
Ohio River Valley regions Wednesday night through Thursday night.
Based on the latest model temperature profiles, it appears that this
mid to late week system will have a bit more warm air with it, so
the precipitation forecast will feature less snow and much smaller
snow accumulations for Wednesday night and early Thursday then
previously forecast. There should be periods of rain/snow mix and
snow late Wednesday night into Thursday morning. Most of the day on
Thursday should feature all rain, as warmer air filters into the
area. Another push of cold air may bring another round of rain snow
mix and some isolated light snow showers to eastern Kentucky late
Thursday night into Friday, as the upper level low departs to our
east. Little if any snow accumulation is expected.

Temperatures through the period will vary from below normal to above
normal depending on the day. Sunday and Thursday should see highs in
the 40s across the area, while Tuesday and Wednesday will most
likely see highs in the 50s. The coldest day of the week could be
Friday, when the mercury may only climb into the 30s area wide.
Nightly lows will generally be in the 30s and 40s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 107 AM EST SAT DEC 3 2016

Models continue to struggle with the llvl stratocu deck moving
across the region, bordering the line between MVFR/VFR, as high
clouds also override across our SW, including KSME and KLOZ.
Latest trends will support these generally MVFR llvl clouds
continuing to take over all TAF sites through the overnight. A BKN
(or at times SCT) MVFR deck will likely persist through much of
the day tomorrow as well. A mid/upper level disturbance will
begin to approach the region tomorrow afternoon/evening, starting
in the south. Meanwhile high pressure will be in control at the
surface. So as llvl clouds begin to clear out (as early as 16Z for
KSME and KLOZ), high clouds will begin thickening to OVC. This
occurrence will happen a little later, closer to 22Z at KSYM.
Expect high clouds to continue to build down throughout the
remainder of the night, but should stay within the high cloud
vicinity through the TAF period. Overall winds will remain
generally light and variable near the surface through the period,
with stronger WNW to W flow aloft. However, the directional
change and increase in flow will be gradual enough to not cause
any wind shear problems throughout the period.

&&

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

$$

SHORT TERM...JMW
LONG TERM...AR
AVIATION...JMW



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