Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 180223

Area Forecast Discussion
National Weather Service Lincoln IL
823 PM CST Sun Dec 17 2017

Issued at 823 PM CST Sun Dec 17 2017

Some scattered areas of light rain continue across the northern
third of Illinois this evening, with short range high-res models
suggesting will continue through the night. Further south, it
should be more of a patchy drizzle, though this will wait until we
start getting a more widespread low stratus overhead. Latest
observations showing a large part of the forecast area southeast
of the Illinois River and north of I-70 with clouds as high as
about 5,000 feet, though this will lower the rest of the evening.
Temperatures should hold fairly steady or only fall a couple
degrees at best. Updated zones/grids have been sent for the latest


.SHORT TERM...(This evening through Monday)
ISSUED AT 310 PM CST Sun Dec 17 2017

Mid afternoon surface analysis shows weak 1015 mb low pressure
over south central Iowa with its warm front extending eastward
across northern IL, just north of I-88. A few light rain showers
lingered north of Lincoln and the latest HRRR models continues
isolated light rain showers over northern CWA into this evening.
Several large breaks in the clouds over central and eastern IL has
allowed temps to elevate into the mid 40s to lower 50s, coolest in
southeast IL. Low/stratus clouds over MO along with some fog and
drizzle will spread ne across central IL during this evening and
linger into Monday morning. Lows tonight only in the upper 30s to
around 40F as sw winds 5-10 mph continue.

Low clouds to decrease from the west during Monday afternoon
though eastern IL likely stays mostly cloudy much of the
afternoon. SW winds 8-15 mph to keep temps on the mild side with
highs 50-55F, while areas ne of I-74 in the upper 40s.

.LONG TERM...(Monday night through Sunday)
ISSUED AT 310 PM CST Sun Dec 17 2017

Skies to become mostly clear during Monday night with sw winds
prevailing, and lows only 35-40F. Tue still looks like a nice day
with partly to mostly sunny skies and highs in the low to mid
50s, even upper 50s sw CWA. A weak cold front pushes through
during Tue afternoon and should come through dry with winds
shifting nw behind it. Models track a low pressure over southern
AR and the southern TN river valley during Tue night keeping its
precipitation south of our CWA, though southern areas will see
more cloud cover. Lows Tue night in the upper 20s northern CWA
and mid 30s along highway 50 in southeast IL. Low pressure tracks
toward the Carolina coast by sunset Wed while weak upper level
ridging into IL keeping us dry. Cooler highs Wed in the 40s with
E/NE winds of 5-10 mph. These temps are still about 10F above

Models deepen a strong upper level trof over the Rockies Wed night
and Thu and continue trending slower ejecting low pressure into
central KS by early Thu afternoon and near the IA/MO border later
Thu evening. Thu now looks dry across CWA even nw of the IL river
valley with just a slight chance of light rain later Thu evening.
Another seasonably mild day Thu in the upper 40s and lower 50s,
with some mid 50s southern CWA. Have slight chance of mainly light
rain showers overnight Thu night across CWA with a mix possible nw
of IL river later Thu night. Lows Thu night range from mid 30s
over IL river valley, to lower 40s in southeast IL from I-70 se.

Surface low deepens into the western Great Lakes by Fri evening
while another low pressure moves into the southern TN river valley
by overnight Fri night. This will likely develop precipitation
across central and eastern IL during Friday and then diminish from
the west during overnight Fri night. Should be warm enough for all
rain on Friday, then changing to a mix or snow from nw to se
during Fri evening and over southeast IL early overnight Fri night.
Could be some light snow accumulations Fri night up to about 1
inch. Highs Fri range from lower 40s nw of IL river to mid 50s by
Lawrenceville. Drier and colder air ushers in on Sat on nw winds.
Lows Fri night in the low to mid 20s in central IL and upper 20s
to around 30F in southeast IL. Highs Sat and Sunday in the upper
20s and lower 30s over IL river valley and upper 30s to near 40F
in southeast IL. Extended models have different solutions for
next Sunday with active southern stream se of central IL and also
a northern stream system moving into the Midwest. Stayed close to
consensus for pops next Sunday which has 20-30% chance of snow
over the IL river valley. But chances of snow could increase
further east across area on Christmas eve/Sunday and Sunday night.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 522 PM CST Sun Dec 17 2017

Currently watching an area of MVFR/IFR ceilings advecting
northeast out of Missouri and southern Illinois. Ceilings over
the central Illinois TAF sites are around 5-7kft as of 23Z, but
will be steadily lowering over the next few hours. Some IFR
conditions expected by about 05Z or so, along with some patchy
drizzle. While ceilings should start to lift Monday morning, it
likely will take until afternoon before rising above 3,000 feet.




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