Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 091753

Area Forecast Discussion
National Weather Service Lincoln IL
1153 AM CST Sat Dec 9 2017

Issued at 1005 AM CST Sat Dec 9 2017

Updated the forecast to address chances of light snow showers and
scattered flurries into midday, and also increase nw winds to
breezier levels. Little or no snow accumulations expected today.
Latest radar mosaic and surface reports continue to show light
snow showers and scattered flurries along and ne of a Canton to
Taylorville to Flora line at 10 am. A 523 dm 500 mb low over
southern Lake MI was embedded in a deep upper level trof along the
IL/IN border late this morning. This clipper system will
gradually shift east and se into central IN early this afternoon
and into western Ohio and eastern KY by dusk. Scattered flurries
currently extend upstream into eastern Iowa and so expect flurries
and isolated light snow showers to linger over central and ne CWA
into early afternoon. Mostly cloudy to overcast skies over IL
though seeing larger breaks in low clouds west of I-55. Expect
these clouds to break up more during the afternoon from the WNW as
skies become partly to mostly sunny by late afternoon. Temps
currently 29-33F will not climb much more due to brisk west to nw
winds 10-20 mph and gusts of 20-30 mph.


.SHORT TERM...(Today and tonight)
ISSUED AT 324 AM CST Sat Dec 9 2017
A deeply amplified pattern over the CONUS this morning is bringing
snow all the way to the Gulf Coast overnight. A weaker system is
moving through the Great Lakes as well, with some flurries/snow
showers in a few waves across Central IL before dawn. Light snow
chances expected through the remainder of the morning, mostly in
the northeast and east before noon. Slightly cooler temperatures
today as the winds shift around to more northwesterly behind a
prefrontal trough. Much cooler temperatures expected overnight
tonight as dense Arctic air drops into the Midwest. This will be
the first of two waves of colder air in the forecast as the flow
remains amplified across North America, and northwesterly in the

.LONG TERM...(Sunday through Friday)
ISSUED AT 324 AM CST Sat Dec 9 2017
Winds coming around to more southerly in a weak ridging on Sunday.
More sunshine expect to the SW, and will result in some
WAA...enough to keep the high temps up into the mid to upper 30s,
and Sun night warmer as well. Smaller shortwaves moving along the
northwesterly flow will bring a series of light chances for snow
and flurries Sunday night/Monday morning, mainly in the north and
northeastern portions of the state...but a small shift in the
forecast track could result in some flurry mention showing up in
the forecast in future runs. Northwesterly flow continues at the
surface and aloft through the first couple days of the work week.
Mondays highs move into the 40s, but the trough/wave bringing snow
chances to the north and east is accompanied by the second round
of deep cold air. Monday night temps drop into the 20s, and teens
Tuesday night. With the deepening cold air and continued
northwesterly flow, have brought the winds up a knot or two from
blended guidance through Midweek. Next chances for snow showing up
in the models between Thu night and Friday night. ECMWF and GFS
have timing about 24 hrs apart on moving a wave through the
region. For now, pops are light in the extended with a lack of
confidence in details.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1150 AM CST Sat Dec 9 2017

A 523 dm 500 mb low over north central IN was embedded in a strong
upper level trof over western parts of lower MI/IN/KY/TN at
midday. This clipper system was still producing scattered light
snow showers and flurries over central and ne IL and will last a
few more hours with MVFR vsbys briefly possible in a few light
snow showers at DEC and CMI. Ceilings have mostly lifted to VFR of
3-5k ft but could briefly reach MVFR of 2.5-3k ft from BMI and DEC
east to CMI for a couple more hours. Low clouds should scattered
out between 23-01Z and brisk nw winds of 12-17 kts and gusts in
the 20s should diminish as well to 5-10 kts early this evening as
upper level trof pulls further east of IL into OH and eastern KY.
Another clipper system takes a further ne track over the central
Great Lakes overnight into Sunday morning, and its light snows
will stay well ne of central IL. A band of mid level clouds of
10-15k ft to spread se across central IL from 08-10Z and then
scatter out after 15Z/Sun. Winds veer sw overnight and increase to
10-15 kts Sunday morning. A cold front front next clipper will
approaching PIA around 18Z/noon on Sunday with winds switching
WNW at PIA around 18Z Sunday.





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