Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 121130
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
530 AM CST Fri Jan 12 2018

.UPDATE...
Updated aviation section for 12z taf issuance

&&

.SHORT TERM...(Today through Sunday night)
Issued at 320 AM CST Fri Jan 12 2018

The main story continues to be the winter storm that currently is
impacting the forecast area. In the wake of the Arctic cold front,
temperatures plummeted below freezing rather quickly. For the most
part, precipitation has changed to sleet overnight. There has been
a narrow band of freezing rain, but reports of measurable ice
accumulations have been less than one-tenth inch. It appears this
will be primarily a sleet storm. Ice accumulations will be
trended downward, and snow/sleet accumulations will be nudged
upward. In general, a solid one to three inches of snow and sleet
are forecast in the warning area. The three-inch amounts would be
in the southwest Indiana and northwest Kentucky area. Ice
accumulations are generally expected to be light, although some
one to two-tenth inch amounts will be forecast in west KY.

The measurable precipitation has already ended west of kpof, but
the eastward progress of the back edge will be slow. The models
keep the back edge of the measurable precip aligned closely with
the 500 mb trough axis. The back edge should reach the kpah/kevv
areas early to mid afternoon, and the khop area early this
evening. With this in mind, the expiration time of the portions
of the Winter Storm Warning se Missouri and sw Illinois will be
moved up to 21z.

Northwest winds behind the Arctic front have gusted to 35 knots at
a few sites overnight. These gusty northwest winds are bringing
temps down more quickly than forecast. Highs today will be lowered
slightly. With the strong winds, wind chill values this morning
will fall to around zero in many areas.

Other than some lingering light snow in the Pennyrile region of
west KY this evening, tonight and Saturday will be partly cloudy
and cold. Overnight temps will be in the teens. Highs Saturday
will be in the mid 20s.

Arctic high pressure will settle directly over the lower Ohio
Valley on Saturday night. The combination of clear skies and
light winds will result in lows in the single digits, except
lower teens along the Tennessee and Arkansas borders.

For Sunday and Sunday night, clouds will increase ahead of a 500 mb
trough that will dig southeastward into the Great Lakes region.
There is a small chance of snow reaching southwest Indiana and parts
of southern Illinois. However, the bulk of this precip will occur on
Monday. See long term discussion below.

.LONG TERM...(Monday through Thursday)
Issued at 320 AM CST Fri Jan 12 2018

Forecast confidence is moderate to high.

The 00Z models agree that there will be a swath of snow with a
clipper system Monday. The timing is still bouncing around a bit,
but it should primarily impact the region on Monday. Behind this
system, another shot of even colder Arctic air will put the area
right back into the deep freeze after warming up to near the
freezing mark on Monday.

Monday night, temperatures may reach zero and if we have fresh snow
cover, lows may drop below zero. Northwest winds will continue
through the night, so wind chills will fall well below zero with at
least the northern half of the area reaching the Wind Chill Advisory
criteria of 10 below zero.

Wind chills may struggle to climb back into positive territory
during the day Tuesday with highs only in the teens. Also would not
be surprised if those numbers trend lower with some snow cover. Wind
chills will drop below zero over the entire region again Tuesday
night and much of the area may flirt with 10 below.

Winds will settle down and may become westerly on Wednesday as the
surface high settles overhead or to the south of the region. Even
with lots of sunshine, temperatures will struggle to reach 20 in
many locations.

The flow aloft will relax and trend toward zonal or even
southwesterly heading into the end of the work week. This will lead
to a moderating trend for temperatures, but how strong is uncertain
at this time.

The 00Z models all have some kind of compact closed low in the zonal
flow aloft, but are varying wildly on the latitude. The 00Z GFS and
the 12Z ECMWF were in agreement in bringing it eastward through the
Tennessee Valley Thursday night into next Friday. Unfortunately, the
00Z ECMWF now takes it into the northern Gulf of Mexico which keeps
our area dry. Based on the previous agreement we have some small
PoPs working east across the southern half of the area Thursday
night through Friday. There could still be cold enough air for snow
initially, so we have rain and snow mentioned for now.

&&

.AVIATION...
Issued at 530 AM CST Fri Jan 12 2018

Large shield of wintry precipitation over the taf sites will
progress slowly east today. Mainly vfr conditions will continue at
kcgi, which is near the back edge of the precip. At kpah, ifr
conditions will be common until the back edge arrives around midday.
The kevv/kowb areas will be ifr at times throughout the day. Precip
type will be mainly sleet early this morning, transitioning to snow
from west to east in the mid and late morning hours. Winds will be
gusting to 30 kt from the north.

Vfr conditions are expected tonight, except some lingering mvfr cigs
around kevv/kowb this evening. Winds will gradually diminish tonight.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Winter Storm Warning until 3 PM CST this afternoon for ILZ075-
     076-080>082-084-085-088-089-092-093.

     Winter Storm Warning until 9 PM CST this evening for ILZ077-078-
     083-086-087-090-091-094.

MO...Winter Storm Warning until 3 PM CST this afternoon for MOZ112-
     114.

     Winter Weather Advisory until noon CST today for MOZ076-086-087-
     100-107>111.

IN...Winter Storm Warning until 9 PM CST this evening for INZ081-082-
     085>088.

KY...Winter Storm Warning until 3 PM CST this afternoon for KYZ004.

     Winter Storm Warning until 9 PM CST this evening for KYZ001>003-
     005>022.

&&

$$

SHORT TERM...MY
LONG TERM...DRS
AVIATION...CN



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