Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 131652

Area Forecast Discussion
National Weather Service Lincoln IL
1052 AM CST Sat Jan 13 2018

Issued at 1052 AM CST Sat Jan 13 2018

Clouds associated with a weak short-wave have generally skirted
central Illinois to the W/SW this morning...leading to abundant
sunshine across the area. Despite the sun, northwesterly winds
occasionally gusting to around 20mph are keeping temperatures from
rebounding. 16z/10am readings range from the single digits
northwest of the Illinois River to the teens elsewhere. Made
updates to hourly sky trends to go with clearer conditions, but
did not alter afternoon highs in the teens and lower 20s.


.SHORT TERM...(Today and tonight)
ISSUED AT 335 AM CST Sat Jan 13 2018

09Z/3 am surface analysis shows 994 mb low pressure in southeast
PA north of Philadelphia, while strong 1045 mb arctic high
pressure was over eastern ND and ridging into the central plains
and upper Midwest. Brisk north winds 12-22 mph and gusts 20-30 mph
was ushering in colder air over central IL. Temps down in the
teens across much of CWA, with Galesburg down to 8F. Wind chills
were in the single digits below zero. Some lake effect
stratocumulus clouds with bases around 3k ft had streamed
southward across the IL counties along the IN border. Could be a
few flurries near IN border early this morning while brunt of
light snow showers will be ne of Vermilion county. Meanwhile mid
level clouds were tracking ese into west central IL toward the IL

00Z forecast models weaken arctic high pressure a bit to 1041 mb
as it moves into the upper MS river valley by 00z/6 pm today and
over the Ohio river valley by sunrise Sunday. Clouds could
increase for a time into mid morning from the west, but then
decrease from nw to se during late morning and afternoon as high
pressure moves in. NNW winds will still be gusty at times this
morning with wind chills in the single digits below zero. NNW to
NW winds will diminish during the afternoon and into tonight as
high pressure approaches. Highs today only in the mid teens north
of Peoria and lower 20s in southeast IL. Fair skies and lighter
winds tonight will bring a colder night with lows of -2F to 4F
above. Areas east of I-57 could get a bit below zero where there
is a 1-3 inch fresh snow cover, deepest near the Wabash river.
Also areas north of Peoria by Galesburg and Lacon could slip a
bit below zero too.

.LONG TERM...(Sunday through Friday)
ISSUED AT 335 AM CST Sat Jan 13 2018

A clipper system will track se from western Canada into northern
IL by sunrise Monday. Clouds will increase ahead of this feature
during Sunday with highs in the lower 20s. Have slight chances of
light snow or flurries nw of the IL river late Sunday afternoon.
Light snow chances increase from nw to se during Sunday night,
then decreasing from the nw during Monday, lingering in southeast
IL Monday afternoon. The highest snowfall probabilities will be
overnight Sunday night into Monday morning with most areas seeing
up to 1 inch. Have 1-2 inches from I-74 ne, while heavier snowfall
amounts appears to be setting up north of I-80 over northern
IL/IN and into WI/MI. Latest 00Z models have overall trended a bit
lower with snowfall amounts over central IL. Lows Sunday night of
15-20F except a few degrees colder by Galesburg. Not much temp
rise over the IL river valley Mon with brisk nw winds developing
Monday morning. Highs Mon in the mid to upper teens over IL river
valley, and 24-29F in southeast IL.

Much colder arctic air continues to filter on on Monday night when
lows will likely reach zero to 6 below zero. Wind chills will
reach 15 to 25 below zero Monday night into Tue morning especially
from I-70 north. A wind chill advisory will eventually be needed
over much of CWA then. Some more clouds drop into central IL
later Monday night into Tue with a disturbance over the central
great lakes. Highs Tue only around 10F. Another frigid night Tue
night with lows around zero southern CWA and zero to 5 below from
i-72 north. Wind chills could reach 15 below or a bit colder nw of
IL river overnight Tue night. Highs Wed in the mid to upper teens
with mostly sunny skies and lighter west winds as 1040 mb arctic
high pressure moves into the mid MS river valley.

As high pressure moves into the southeast states thereafter, and
upper level flow become more zonal, temperatures expected to
modify Thu thru Sat with highs of 30-35F on Thu, upper 30s/lower
40s Friday and 40s on Saturday. Dry wx looks to prevail rest of
the week as a southern stream cutoff low tracks into the southern
plains/lower ms river valley Thu night and Friday, keeping its
moisture south of IL.

A milder and more unsettled weather pattern could take shape Jan
20-26th. Climate Prediction Center (CPC`s) 8-14 day outlook has
55-65% chance of above normal temperatures and 60-65% chance of
above normal precipitation over IL.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 535 AM CST Sat Jan 13 2018

VFR conditions should continue across the central IL airports
through 12Z/6 am Sunday. 1045 mb arctic high pressure over the
eastern Dakotas, will track into WI/IL by overnight and bring fair
weather. NNW winds of 10-17 kts this morning will gust 20-25 kts
from BMI and DEC east to CMI this morning. NNW to NW winds to
diminish to 5-10 kts during the afternoon and then light at
sunset. Winds veer SE late tonight and remain light as high
pressure settles over the Ohio river valley by dawn Sunday. Most
of the stratocumulus clouds 3-4k ft streaming off Lake MI will
stay east of CMI, and just carried scattered 3.5k ft at CMI into
mid morning. Otherwise a broken area of mid level clouds of 8-12k
ft will track se over SPI this morning with DEC possibly going
broken for a time this morning. I-74 taf sites should stay
scattered with these clouds. Mid level clouds to scatter out along
I-72 around 18Z with fair skies rest of the day and tonight. Some
cirrus clouds move in late tonight.




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