Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 161721

Area Forecast Discussion
National Weather Service Lincoln IL
1121 AM CST Tue Jan 16 2018

Issued at 904 AM CST Tue Jan 16 2018

Latest water vapor imagery shows a sharp trough axis from
southern Lake Michigan southwestward to Missouri. Synoptic lift
associated with this feature has triggered a band of snow-showers
across north-central Illinois this morning...with visibilities
reduced to 1 to 2 miles at times. Have even had a few reports of
minor snow accumulations of a couple tenths of an inch. Based on
radar trends and recent obs, have raised PoPs as this band drops
southward through the area to feature scattered snow-shower
wording. Any accumulating snow will drop south of the area by mid
to late afternoon, leaving behind only a few flurries into the
evening. Main story today will be the bitter cold, with high
temperatures only reaching the teens. Wind-chills will hover in
the 10 below to 20 below range for the next couple of hours before
gradually warming toward midday. As a result, the Wind Chill
Advisory will remain in effect until noon.


.SHORT TERM...(Today and tonight)
ISSUED AT 345 AM CST Tue Jan 16 2018

The 09Z/3 am surface analysis shows strong 1050 mb arctic high
pressure over northeast ND and ridging southward across the great
plains and also into the mid MS river valley. This was providing
bitter cold conditions early this morning with temps ranging from
4 above to 4 below zero and wind chills of 15-25F below zero.
Radar mosaic shows a persistent band of moderate snows along and
se of the Ohio river into KY, AR and nw TN and this should stay se
of Evansville today. Some light snow showers and flurries were in
northern IL along and north of I-80 and these are dropping
southward toward Knox, Stark and Marshall counties early this
morning. These are associated with a strong 530 dm 500 mb low
along the eastern WI/IL border between Chicago and Milwaukee and
embedded in a deep upper level trof extending sw into KS.

As the strong upper level trof pivots southeast across central and
southeast IL during today, it will spread a few light snow showers
and scattered flurries se with it, reaching southeast IL toward
midday. Broken stratocumulus clouds currently spreading southward
toward Peoria and Bloomington, will spread across rest of central
and southeast IL during this morning, so skies becoming mostly
cloudy today. Cold highs in the 12-18F range today, with areas ne
of I-74 actually being a couple degrees higher than sw CWA due to
a bit higher 925 mb temperatures, and coldest 925-850 mb core is
over southern MO. Wind chills will be in the 12-22 below zero
range much of this morning with a few cities like Bloomington down
to 25 below zero with WNW winds 10-17 mph and gusts to around 20
mph. Will keep the wind chill advisory going this morning until
noon, though it may eventually need to be cancelled a couple hours
early especially for our southeast counties.

Upper level trof that is projected to be over southeast IL at
sunset will move se to the Ohio river by midnight tonight, with
flurries gradually diminishing in eastern/se IL during this
evening. Arctic high pressure to settle into the Ozarks (1043 mb)
by dawn Wed. Skies will become partly cloudy by overnight with
mostly clear skies by IL river overnight. Another very cold night
ahead with lows of zero to 6 above. Lighter WNW winds so wind
chills generally in the single digits below zero tonight, though
Galesburg could have wind chills to 10 below zero or a bit colder.
So thinking we will be shy of wind chill advisory criteria of 15
below zero.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 345 AM CST Tue Jan 16 2018

Upper level trof pushes further away from IL across the
Appalachians on Wed, while arctic high pressure will move into
eastern AR and western TN by sunset Wed. Mostly sunny skies
expected Wed with a few more stratocumulus clouds from I-74 ne and
near the IN border. Highs mostly in the lower 20s Wed with
Jacksonville near 25F. WSW winds of 7-14 mph on Wed with wind
chills still in single digits below zero Wed morning. Interesting
to note that central IL will actually be colder than Fairbanks AK
today and Wed.

High pressure settles into the lower MS river valley on Thu while
a northern stream upper level trof tracks across the northern
Great Lakes Thu and Thu night, keeping its light snows north of
IL. Ample sunshine Thu combined with increasing sw winds of 10-15
mph and gusts 20-25 mph to modify temps closer to normal Thu with
highs in the 30s, ranging from 32F at Danville to 40F from
Jacksonville sw. Lows Thu night of 20-25F, similar to expected
highs on Wed.

Fair weather continues Friday with mostly sunny skies along with
moderating temperatures as high pressure will be across the
southeast states and some upper level ridging into IL. Highs Fri
in the low to mid 40s, except upper 30s by Danville and Paris.
Lows Fri night in the low to mid 30s.

00Z models continue to show a strong upper level trof digging over
the Rockies late this week with IL getting in a more unsettled sw
upper level flow this weekend. Surface low ejects into OK
panhandle Sat night and ejects ne into the western great lakes
late Sunday night. Surface low passes nw of our CWA so we should
be on the mild side of this system with most precipitation falling
as rain. Have isolated light rain showers possible Sat and Sat
evening with highs Sat in the upper 40s to lower 50s. Chance of
rain showers Sat night especially overnight with showers likely on
Sunday and Sunday night as cold front pushes east over IL Sunday
evening. Could be isolated thunderstorms late Sunday
afternoon/evening with best chances for these in southern MO, but
may eventually need mention into part of our CWA, especially
southeast counties. Mild highs Sunday in the low to mid 50s.

An upper level trof over IL Monday keep chances of light rain/snow
showers around along with mostly cloudy skies, with temperatures
cooling closer to normal, highs in the mid to upper 30s central
IL and lower 40s in southeast IL. Dry weather expected Monday
night and Tue of next week with highs Tue in the upper 30s to mid

Climate Prediction Center`s (CPC) 8-14 Day Outlook for Jan 23-29
continues to trend toward a milder and wetter wx pattern. CPC has
a 45-50% chance of above normal temperatures and a 50-55% chance
of above normal precipitation over central and southeast IL during
the last week of January. This may offset bitter cold conditions
that we have experienced much of the past 3 weeks since Christmas


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1121 AM CST Tue Jan 16 2018

Scattered snow-showers will persist at the central Illinois
terminals through mid-afternoon, before the precip gradually
shifts further south and dissipates later in the day. While
occasional breaks in the overcast have been observed this morning,
ceilings have generally been in the MVFR category. All model data
suggests the MVFR ceilings will persist until skies clear from
northwest to southeast this evening. Based on satellite trends and
HRRR forecast, have scattered the clouds at KPIA at 03z...then
further east to KCMI by 05z. Winds will initially be from the
NW at 10-15kt this afternoon, then will decrease and back to W/SW
by Wednesday morning.


Wind Chill Advisory until noon CST today for ILZ027>031-036>038-



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