Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 081759
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1159 AM CST Fri Dec 8 2017

.UPDATE...
Issued at 1045 AM CST Fri Dec 8 2017

A fair amount of sunshine across central IL this morning with a
band of cirrus clouds streaming ne across the Wabash river valley
at late morning. Brunt of these clouds are staying se of the Ohio
river with a winter weather system affecting the southern states
today. Upstream a band of mid level clouds was breaking up as they
were pressing se into nw IL. So more sunshine now expected over
central IL today with sunny skies late this morning becoming
partly to mostly sunny during the afternoon. 1024 mb high pressure
over the mid MS and Ohio river valleys while a cold front was over
central parts of WI/IA. SW winds 10-15 mph over central IL with
gusts to 20 mph to moderate temperatures into the mid to upper 30s
for highs by mid afternoon.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 217 AM CST Fri Dec 8 2017

Clipper type system was located over far northern Manitoba early
this morning, and will quickly drop southward through the day. The
shorter range models are in good agreement with this feature
reaching northwest Wisconsin by early evening, with a cold front
swinging across central Illinois late in the night. Focus for the
snow with this feature remains largely in the post-midnight time
frame, with around a half inch accumulation possible along and
north of I-74. Latest European model suggests a half inch possible
as far south as Springfield and Mattoon, while the NAM bypasses
central Illinois entirely. Will lean a little more toward the GFS
solution, but something to keep an eye on.

Ahead of this feature, southwest winds and a decent amount of
sunshine will lead to some milder temperatures. Highs in the mid-
upper 30s should be common over the forecast area.

.LONG TERM...(Saturday through Thursday)
ISSUED AT 217 AM CST Fri Dec 8 2017

A little bit of light snow and flurries will linger early
Saturday, but the front will quickly depart. This will mark the
start of an extended period of mainly dry conditions. Clipper
systems Monday night and Thursday largely stay to our north. Both
the GFS and ECMWF models suggest at one time or another, the
potential for fast moving streaks of light precipitation, as fast
moving waves race through the northwest flow. Such streaks are
difficult to peg this far out, though.

The Arctic air will remain entrenched across Ontario and Quebec
during the period, but periodic shortwaves will drag lobes of
colder air southward. Saturday, and Monday night through Tuesday,
look to be the colder parts of the forecast period. Outside of
these times, highs should recover into the 40s in many areas.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1155 AM CST Fri Dec 8 2017

VFR conditions are expected to continue across the central IL
airports through 08Z as mid and high clouds increase from the nw
after sunset. A clipper system north of MN over western Ontario
will dive into central IL between 09-12Z Sat and bring a chance of
light snow and flurries to areas ne of SPI. Ceilings will drop to
MVFR of 2-3k ft between 08-12Z and linger Sat morning. Upper level
short wave trof to shift east of IL toward 18Z/noon on Saturday.
SW winds of 10-15 kts and gusts near 20 kts early this afternoon
to gradually diminish to around 10 kts by sunset. Winds shift west
early overnight and then NW later tonight into Sat and increase to
12-17 kts and gusts of 18-25 kts late tonight and Sat morning.

&&

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

&&

$$

UPDATE...07
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...07



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