Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 100534
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1134 PM CST Sat Dec 9 2017

.UPDATE...
Issued at 858 PM CST Sat Dec 9 2017

Satellite loops indicates that high clouds have moved over the CWA
this evening and trends are that these clouds will continue to
move across the area overnight. With light west winds, one would
expect overnight lows to drop to near current dwpts in the middle
teens. However, high clouds and winds becoming southwesterly later
should keep temps from fall that far. So, current forecast for
overnight lows around 20 still looks good. Additional cloud cover
will move into the area after midnight, keeping temps in the north
part of the CWA from dropping too much as well. So, current
forecast looks good and no update needed at this time.

&&

.SHORT TERM...(This evening through Sunday)
ISSUED AT 305 PM CST Sat Dec 9 2017

A 524 dm 500 mb low over northeast IN was within a strong upper
level trof over the central Ohio river valley. Stratocumulus
clouds lingered over much of IL into eastern IA and far ne MO at
mid afternoon, along with scattered flurries and isolated light
snow showers over central and ne IL. As upper level low/trof pulls
further away from IL by early evening, expect clouds and brisk NW
winds of 15-25 mph and gusts 25-35 mph to diminish. Though some
mid/high clouds will increase from the nw during overnight. A cold
night ahead with lows around 20F.

Increasing sw winds on Sunday to moderate temperatures into the
upper 30s and lower 40s for highs, close to seasonable levels. A
partly to mostly sunny day overall with more clouds ne of I-74
where the next clipper system dives se into the central Great
Lakes.

.LONG TERM...(Sunday night through Saturday)
ISSUED AT 305 PM CST Sat Dec 9 2017

Lows Sunday night in the low to mid 20s as winds diminish light
and clouds increase from the NNW overnight Sunday night. A
stronger clipper systems dives se into our area on Monday, though
the brunt of its precipitation skirts just ne of CWA across
northern/ne IL. SW breezes brings milder highs in the 40s Monday
with far SW CWA over Scott and Clay counties approaching 50F.
This will likely be our mildest day during the next 7 days.

Colder air filters back into the area behind this clipper system
during Monday night and Tue on brisk nw winds. Highs Tue similar
to todays readings in the upper 20s and lower 30s, coldest ne CWA.

12Z models differ with handling a clipper system during mid week
around Wed and stayed close to consensus of models until
differences sorted out. This places slight pops in sw CWA on Wed
afternoon. Then 20-40% chance of light snow overnight Wed night
from I-72 north with highest pops over northern/ne IL. Highs Wed
in the lower 30s ne CWA and upper 30s sw CWA. Highs on Thu
moderate a bit more to mid 30s northern CWA to around 40F
southern reaches of CWA.

The persistent upper level trof over the eastern states much of
next week appears to break down toward the end of the week as
upper level flow tries to flatten out somewhat by Friday. This to
keep clipper system further ne of IL while our area enjoys a dry
and milder weather for Friday into next Saturday. Highs Fri in
the upper 30s and lower 40s, warms into the mid 40s to around 50F
for Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1134 PM CST Sat Dec 9 2017

VFR conditions will prevail at all TAF sites next 24hrs. High
cirrus is over the sites currently, but shortly after midnight,
mid clouds around 10kft will begin to move over the area and bring
a 10kft cig to all sites for 3-5 hours overnight. This patch of
mid clouds will not last long and all sites should have scattered
out by morning. Then it appears a dry sfc trough will rotate
through the area but clouds will remain scattered mid or high
clouds. The scattered mid clouds will remain over the area into
the evening hours. Winds will be southwest overnight and then
increase in speeds with gust of 20-22kts by morning once the mid
clouds move off to the east. Winds will diminish some during the
afternoon as the sfc trough goes by and winds become northwest for
the remainder of the TAF period.

&&

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

$$

UPDATE...Auten
SHORT TERM...07
LONG TERM...07
AVIATION...Auten


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