Area Forecast Discussion
Issued by NWS Central Illinois

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314
FXUS63 KILX 102342
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
542 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
evening.

.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 00Z TAFS through 00Z Monday evening)
Issued at 542 PM CST Sun Dec 10 2017

A brief disturbance passing by the the north of central IL this
evening will bring a deck of MVFR cigs just north of the I-74
terminals this evening, with a slim chance of MVFR cigs reaching
KPIA-KBMI-KCMI. Have included SCT030 this evening to account for
this. This will pass by with low cloud clearing overnight. Another
low pressure system will move into the area Monday afternoon,
bringing another increase in cloud cover but little chance of any
precipitation this far south by 00Z Tuesday. Winds NW 5-10 kts
this evening decreasing overnight. S-SW winds 10-15 kts developing
Monday morning with the approach of the next low pressure system,
switching to W-NW toward the end of the forecast period.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SHORT TERM...07
LONG TERM...07
AVIATION...37



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