054
FXUS63 KILX 220513
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1113 PM CST Fri Nov 21 2025

.KEY MESSAGES...

- Periods of rain will persist through the evening hours before
  departing by Saturday morning.

- Another round of rain is likely (greater than 80% chance) Monday
  evening into Tuesday morning. Current forecast guidance
  suggests amounts will generally range between 0.25"-0.5".

- A sharp cold front will push across the area on Wednesday with
  temperatures slipping into the 20s by Thanksgiving morning.

&&

.UPDATE...
Issued at 853 PM CST Fri Nov 21 2025

Forecast appears generally on track this evening as a band of
deformation zone frontogenesis promotes shower activity behind a
surface low set to track eastward up the Ohio Valley overnight.
Radar is showing this band rapidly eroding on the western side
over northern MO and shifting slowly southeastward on the northern
flank, which should bring a fairly rapid diminishment of
precipitation over central IL after midnight...earlier north of
Peoria. Updates have been made for minor short term trends in
location of the rain band.

Enough dry air above the surface and lingering high cloud cover
looks to prevent fog formation overnight as precipitation comes to
an end, but with relatively light wind and recent rain, this will
need to be monitored.

Lows still look to range from lower 30s near and north of the IL
River Valley to mid 40s south of I-72.

37

&&

.DISCUSSION...
Issued at 1219 PM CST Fri Nov 21 2025

Periods of rain, drizzle and fog will persist through this
evening as a loosely-organized frontal system slides out of the
Missouri Ozarks and toward the Lower Ohio River Valley. Overall
trends in hi-res guidance have shifted the rainfall axis slightly
further north as an east-west band of 850-700 mb frontogenesis
moves roughly parallel to the I-72 corridor by evening and helps
to support a narrow area of moderate rainfall. Total QPF looks
greatest in between the I-72 and I-70 corridors where the latest
RRFS guidance supports between 0.25"-0.75", with locally higher
amounts up to 1.25" east of I-57 (i.e. portions of west-central
and southwest IL).

Precip will quickly diminish into Saturday morning as large-scale
subsidence works in behind the departing upper-level shortwave
and attendant frontal system. An abundance of sunshine will emerge
Saturday morning and persist through Monday as surface high
pressure builds across the region downwind of an upper ridge axis.
Temperatures will respond by warming into the mid- to upper-50s
each afternoon Saturday through Monday.

Another frontal system will push across central Illinois Monday
evening into Tuesday as a pair of mid-level troughs attempt to
phase together over the central US. A strong low-level jet (40+
kts) will veer into our region ahead of the front, giving us a
healthy injection of moisture and shear, but the greatest
instability and convective chances appear to be confined to the
Lower Mississippi Valley ahead of the leading trough. Further
north across central Illinois, rain is likely (greater than 80%
chance, per NBM guidance). And, poking around the various ensemble
and multi-model guidance, the Mean QPF generally ranges from
0.25"-0.5" with this next round of rainfall.

The well-advertised cold snap will arrive on Wednesday and
continues through at least Thursday with daily highs in the 40s
and overnight lows in the 20s. Breezy northwest winds on
Thanksgiving morning will yield wind chill values in the teens,
perhaps leading to some limited cold-weather impacts for outdoor
events.

An unusual amount of forecast uncertainty then exists Friday
onward, and especially into early December. As it stands today,
there is about a 1 in 6 chance for wintry precip to occur between
Friday and Saturday in areas west of I-55; sources: both 13z NBM
and 00z LREF. Then, sometime between the Sunday and Tuesday
timeframe of that following week, an impactful winter system is
looking increasingly likely. For us here in central Illinois, the
compass is pointing most strongly toward being on the warm side of
this system, at least for now.


MJA

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1113 PM CST Fri Nov 21 2025

Precipitation will dissipate and cigs/vsbys will improve as a low
pressure system departs to the east. MVFR vsbys with localized
IFR-MVFR cigs for all central IL terminals southeast of KPIA will
improve to VFR by 08Z-09Z. Winds NNE 5-10 kts, becoming light and
variable by 12Z. SW winds 6-10 kts developing by 18Z.

37

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$