Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 091120
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
520 AM CST Sat Dec 9 2017

.UPDATE...
Issued at 520 AM CST Sat Dec 9 2017

Updated for 12Z aviation forecast discussion.

&&

.SHORT TERM...(Today through Monday night)
Issued at 231 AM CST Sat Dec 9 2017

Main challenge in the near term will be light snow and flurry
chances this morning. Latest radar mosaic shows a large area of
scattered snow showers and flurries over the Great Lakes region
extending down into central Illinois and central Indiana in
association with a sfc low over Wisconsin, which will head east
southeast toward southern Michigan by this afternoon. Mid level
moisture is almost here but the lower level moisture will be lagging
behind a bit and will start to arrive closer to 12Z. That is when we
should see chances for some flurries or light snow showers to
arrive/develop.

Looking at all available short term models, best chances for
very light snowfall accumulations will be in the Wabash River Valley
of southeast IL, southwest IN and the northern Pennyrile region of
west KY, during the morning hours. However, chances for flurries
will be seen across a good part of our area, namely east of the
Mississippi River as low level lapse rates steepen later this
morning.

Main timing of the best low to mid level forcing associated with
an incoming cold front will be from 12Z- 15Z and then it drops off
considerably after that. There is some dry air in the lowest few
thousand feet that the snow will have to overcome at first.

In addition, relatively warm ground temperatures should preclude
any decent snowfall amounts, unless an isolated heavier snow
shower develops, which is more likely in our northeastern
counties. Kept forecast snowfall amounts in those areas under a
half of an inch though for now. But even a few tenths of an inch
of snow accumulation can wreak havoc especially since it is the
first snowfall of the season. We will be closely monitoring the
event this morning.

By this afternoon, we will see the lower level moisture shifting
east with time, so the chances for light snow showers or flurries
will be coming to an end. But can`t rule out some lingering
flakes in our far eastern counties in the early afternoon before
it ends though.

Northwest winds will be picking up by late morning into the
afternoon as a cold front plows through. However, winds will
become southwesterly late tonight ahead of another cold front that
will pass through here dry on Sunday. 850 mb temperatures rise
above zero on Sunday so we should be able to reach into the 40s
for highs, possibly even close to 50 in southeast MO. Warm air
advection continues into Monday and we should see a surge in
temperatures to where most locations should rise into the 50s.
Depending on the timing of the next frontal boundary, we could see
falling temperatures during the afternoon hours however. The
front is progged to come through dry.

.LONG TERM...(Tuesday through Friday)
Issued at 231 AM CST Sat Dec 9 2017

Will continue to see a persistent upper trof over the eastern part
of the conus, and ridge out west. The pattern should break down
slightly by the end of the week. A surface high pressure ridge will
move southeast across the area Tuesday through Wednesday. A weak
surface boundary should move through dry Thursday, with dry weather
continuing through Friday as high pressure returns. Used a GFS/ECMWF
blend through Thursday, then more of an ECENS/GEFS mean approach for
Friday. After an unseasonably cool day Tuesday, near normal
temperatures are anticipated Wednesday through Friday.

&&

.AVIATION...
Issued at 520 AM CST Sat Dec 9 2017

Incoming cloud deck is initially VFR but some intermittent MVFR
clouds will likely invade the terminals from time to time this
morning. Some light snow or flurries are also possible mainly at
KEVV/KOWB this morning. A MVFR cig may stick around for the late
morning into the afternoon but the best chance of this occurring
would be at KEVV/KOWB. Clouds will depart this evening. Winds will
become gusty out of the northwest later this morning but then
subside this evening and eventually come around to the southwest
late tonight.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&

$$



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