Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 121801
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1201 PM CST Fri Jan 12 2018

.UPDATE...
Issued at 1059 AM CST Fri Jan 12 2018

Light to moderate snow continues to fall across the far E/SE KILX
CWA this morning...primarily along/east of a Robinson to Olney
line. Based on radar trends and 12z ARW/NMM forecasts, it appears
the snow will depart into Indiana by early afternoon. Additional
accumulations of up to 1 inch are possible across parts of
Crawford and Lawrence counties before the snow ends. Further west,
clouds prevail across the remainder of central Illinois: however,
the overcast has thinned considerably west of the Illinois River.
Despite the decrease in cloud cover, additional diurnal clouds are
rapidly re-developing as per latest visible satellite imagery and
will slow the eastward progression of any substantial clearing
today. As a result, think areas west of I-55 will eventually
become partly sunny by mid to late afternoon before completely
clearing after sunset. Further east, overcast conditions will
prevail through the balance of the day. High temperatures will
mainly be in the lower to middle 20s.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 305 AM CST Fri Jan 12 2018

Deep upper trough was edging toward the Mississippi River early
this morning. Precipitation continues to surge northeast out of
Arkansas, and somewhat of a break over east central Illinois, is
filling in once again. Surface obs and radar mosaics continue to
indicate some sleet mixing in with the snow at times, though the
freezing rain reports have been diminishing some. This trend will
continue through sunrise, then the precipitation will start to get
pushed east as the trough approaches. Will go ahead and extend
the Winter Weather Advisory from I-57 east through noon, and keep
it in most areas further west until the original 6 am expiration.
However, will go ahead and remove the counties along I-55.

Last of the precipitation should be out of the far southeast CWA
by mid afternoon. Wind trajectories off Lake Michigan do bring
lake effect snow southward along the Illinois/Indiana border
tonight, and can`t rule out a few flurries perhaps making it as
far south as Danville.

High temperatures today will be about 30-35 degrees colder than
yesterday, and single digit lows are likely as far southeast as
I-55 tonight.

.LONG TERM...(Saturday through Thursday)
ISSUED AT 305 AM CST Fri Jan 12 2018

The cold air pattern will continue well into next week, with a
secondary surge of Arctic air coming in Monday. The worst of the
cold will be with this particular surge, with temperatures falling
through the daytime and may be below zero as early as sunset near
Galesburg. Widespread wind chills of 15-25 below zero expected
Monday night, with most areas seeing temperatures near or below
zero. Pattern shift currently is projected by the longer range
models toward the latter part of the week.

Not a lot of change with the clipper system Sunday night and
Monday, in terms of timing. The latest GFS appears a bit weaker
with it, but the ECMWF and Canadian have decent coverage of light
snow. The tail end of the NAM is slower, but also supports a
broader coverage. Still looking like a 1-2 inch snow event. High
pressure behind it will result in dry conditions through mid week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1201 PM CST Fri Jan 12 2018

MVFR ceilings will persist at the central Illinois terminals this
afternoon before gradually clearing from west to east toward
sunset. Despite partial clearing across the Illinois River Valley
earlier, additional diurnal clouds have now filled in...resulting
in mostly cloudy skies as far west as the Mississippi River. These
clouds will quickly dissipate late this afternoon, with soundings
suggesting clearing at KPIA by 23z. Further east, MVFR ceilings
will prevail at KCMI through at least 03z. Once the clouds exit, a
period of mostly clear skies will be observed tonight before a
weak disturbance spreads mainly mid/high clouds back into the area
by Saturday morning. Winds will be strong from the north
today...with gusts generally in the 20-30kt range. Gusts will
subside after sunset: however, brisk northerly winds of 10-15kt
will continue through the night.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 4 PM CST this afternoon for ILZ068-
073.

&&

$$

UPDATE...Barnes
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Barnes



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