Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 102110

Area Forecast Discussion
National Weather Service Lincoln IL
310 PM CST Sun Dec 10 2017

.SHORT TERM...(This evening through Monday)
ISSUED AT 305 PM CST Sun Dec 10 2017

A band of mid and high clouds quickly exited southeast IL early
this afternoon leaving ample sunshine this afternoon over CWA.
Some more cirrus clouds are streaming se from IA into nw IL while
stratocumulus cloud desk was along and north of I-88. A frontal
boundary had pushed se toward I-72 at mid afternoon with breezy sw
winds gusting 20-30 mph ahead of it turning west to nw behind it.
Milder temperatures this afternoon ranged from 39-45F.

A clipper system/short wave over WI will dive se across the Great
Lakes tonight and keep its light precipitation and brunt of its
low clouds ne of central IL. Lows tonight in the low to mid 20s.
A stronger short wave/clipper system along the central Alberta and
Saskatchewan province line will dive se into the Midwest by
Monday afternoon. This will increase clouds over the area later
tonight and Monday. Highs Monday range from lower 40s from I-74 ne
to the upper 40s to near 50F sw CWA. Isolated light rain showers
possible north of Peoria over mainly Knox, Stark and Marshall
counties Mon afternoon. Another cold front to pass east across CWA
during Monday afternoon, and thru southeast IL early Monday


.LONG TERM...(Monday night through Sunday)
ISSUED AT 305 PM CST Sun Dec 10 2017

Brunt of this clipper`s precipitation to pass ne of CWA Monday
afternoon and Monday evening, though did continue chances of
sprinkles and flurries ne CWA Monday evening. Brisk nw winds usher
in colder air during Monday night. Lows in the upper teens north
of Peoria and mid 20s in southeast IL. Brisk nw winds continue on
Tue with partly to mostly sunny skies, and colder highs in the
upper 20s and lower 30s.

Models differ with handling the short wave/clipper around Wed as
it dives se over the Midwest. GFS model keeps our area dry on Wed
while GEM model has some qpf over area Tue night while ECMWF model
has qpf on Wed afternoon. Due to model differences between each
other and from previous runs, sided with consensus which is
keeping us dry from Tue thru Wed night. A cold night Tue night
with lows 15-21F. Highs Wed in the mid to upper 30s, with
areas from Springfield sw around 40F.

GFS and GEM models are stronger with upper level trof over area and
has qpf over area on Thu along while Ecmwf is weaker with this
trof and dry. Consensus of model just has slight pops in Wabash
river valley Thu afternoon while most of CWA is dry which we
followed. Highs Thu again in the mid to upper 30s. Upper level
trof lingering over Ohio river valley Fri morning finally appears
to pull away from IL for the weekend with moderating temperatures.
Highs in the upper 30s to around 40F Fri, climb into the mid 40s
to around 50F on Saturday and Sunday. GEM model is odd model that
has qpf over part of CWA Sat and Sat evening while ECMWF and GFS
models are dry and sided in that direction.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1150 AM CST Sun Dec 10 2017

A cold front near the IL river by PIA at midday will push se to
CMI and DEC between 19-20Z. Brisk sw winds of 12-18 kts and gusts
of 20-27 kts will switch west and then nw behind the cold front.
NW winds then diminish to around 5 kts around 00Z/6 pm and veer
SSW overnight, increasing to 9-14 kts after 14Z Monday morning. A
batch of mid/high clouds se of the IL river will decrease from
the nw next few hours. A stratocumulus clouds deck with MVFR
ceilings over WI and ne IA will slide se and should pass ne of
central IL taf sites, getting closest to I-74 by early this
evening. Will still need to keep an eye of these MVFR clouds, but
most models keep VFR conditions over central IL airports next 24
hours. Another batch of mid/high clouds passes se across central
IL overnight into Monday morning.





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