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000
FXUS63 KILX 062111
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
311 PM CST Fri Dec 6 2013

.DISCUSSION...
ISSUED 311 PM CST Fri Dec 6 2013

Overall, models look very similar in the short term with the upper
level pattern through the weekend and into the beginning of next
week. On the surface, the models look in good agreement with
handling of the high pressure area. The models have some minor
differences with a weaker weather system coming through the area
Sunday/Sunday night, so resulting weather forecast will be the
same. Main concern is the weak weather system Sunday/Sun night as
it moves through the area. The other concern is ending of the
current winter storm warning in southeast Illinois. Radar loops
show snow rapidly moving east and northeast through the area. Snow
is still falling over the area and should be out of the cwa around
6pm. So will let the warning continue until 6pm and the evening
shift can cancel it as needed.

SHORT TERM...Tonight through Monday

Moderate snow continues over the southeast and should be out of
the area by 6pm. Winter storm warning will continue until 6pm.
Then after 6pm there will remain a slight chance of snow in the
southeast that should completely end around 9pm. Then dry weather
will dominate the area through sat night. Then a weak weather
system/surface lower pressure area will move across the area
Sunday and Sunday night. This system will have some lower level
moisture but not a lot of mid and upper level moisture.
Temperatures on the surface will remain below freezing so pcpn
should be in the form of snow. However, at the top of the cloud
deck, temps will be around -10C. This means that the location of
where the pcpn will start as it descends through the cloud will
have a mix of ice crystals and super cooled water droplets. With
the temperatures in the atmosphere remaining below freezing, the
pcpn as it falls will change much. So, believe the pcpn that
reaches the ground could be a mix of snow and freezing drizzle.
So, given that it`s a weak system as it moves over our area, will
have chance of snow and occasional freezing drizzle in the
forecast for Sunday afternoon through Sunday evening. As this
system moves northeast, the pcpn will quickly end over the cwa.
Once this moves through, dry weather will return for Monday.

Temps through the period will remain well below normal. Coldest
temps will be tonight, with many areas experiencing single digits.
Combined with the northwest winds, wind chills will be below zero
tonight and several times through the period. The warmest
afternoon highs will be Sunday afternoon, though still below freezing.

LONG TERM...Monday night through Friday

Dry weather is expected through the period as the upper level
pattern becomes zonal. By the end of the period, Fri of next
week, the pattern begins to shift some. Temps through most of the
period will remain below freezing, however, with the small change
to the pattern, temps should rise to above freezing by Friday.

Auten
&&

.AVIATION...
ISSUED 1153 AM CST Fri Dec 6 2013

VFR conditions will continue at central and eastern Illinois TAF
sites for the next 24 hours, as the main winter storm system
remains south and southeast of the region before pulling out of
the lower Ohio Valley.

The latest IR satellite loop shows a broken deck of altocumulus
with ceilings around 8-10 kFT. The last in a series of upper level
disturbances will move through the lower Ohio valley this
afternoon, and depart by mid-evening. The northern extent of the
light snow could move into Decatur and Champaign after 20Z this
afternoon, although ceilings and visibility will remain well into
the VFR category. A few light snow showers/flurries are possible
toward the I-55 corridor from KSPI-KBMI early this afternoon
before more dry air and gradual clearing moves in during the
evening.

With the storm system pulling away to the east and a strong Arctic
high approaching from the Plains, very cold and clear conditions
are expected from after midnight tonight through Saturday. The
pressure gradient will remain on the moderate side, so a north
wind around 10 kts will prevail into Saturday.

Miller
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING until 6 PM CST this evening FOR ILZ067-068-
071>073.

WINTER WEATHER ADVISORY until 6 PM CST this evening FOR ILZ056-
057-061>063-066.

&&

$$