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FXUS63 KILX 081049
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
449 AM CST Sat Nov 8 2025

.KEY MESSAGES...

- Rain is likely this evening (60-90% chance). Precipitation could
  mix with or changeover to snow during the late evening/overnight
  hours, especially along and north of I-74.

- Most areas will see little to no snow accumulation tonight, but
  there is a low chance (10-15%) for a narrow band of up to 2" of
  snow, mainly in areas from Canton to Hoopeston northward.
  Accumulations are most likely on grassy or elevated surfaces.
  When snow is falling, breezy winds gusting 25-30 mph could
  result in visibility below 1 mile.

- Sharply colder temperatures are expected Sunday and Monday, with
  highs in the mid 30s to low 40s, and lows in the low 20s. On
  Monday morning, wind chill values will drop as low as 10 degrees
  above zero.

&&

.DISCUSSION...
Issued at 225 AM CST Sat Nov 8 2025

*** TODAY ***

After a seasonably warm week featuring several days of the temps
in the 60s, an early taste of winter is in store this weekend
into early week. Early Sat AM, a shortwave was located near the
MT/ND border, digging SE in time, while a much deeper upper low
was positioned near James Bay. Skies were clear across the ILX CWA
at 1am/07z, although a stratocumulus deck was present north of
I-80 (gradually sagging southward) and the cirrus shield
associated with the approaching shortwave was nearing the MS River
(spreading east in time). Skies will quickly transition to mostly
cloudy by mid- morning. In advance of this system, a stalled
front draped across the CWA will result in a large gradient in
high temps today, ranging from the upper 40s north of PIA to
low/mid 60s south of I-70. Precip from the approaching shortwave
is set to push in from west to east during the mid/late afternoon
(20-40% chance of rain west of I-55 by mid-afternoon).

*** TONIGHT ***

A challenging forecast exists this evening owing to an increasing
signal for robust, banded forcing in a cooling but marginal
thermodynamic environment for snow accumulations. The sfc low is
still expected to track across the ILX CWA tonight, with guidance
continuing to depict a band of FGEN on the N/NW side of the low.
QPF amounts from a variety of models (NAM, RAP, CAMs) are all
hinting at a band of higher totals setting up in a SW-NE oriented
band near/north of I-74, with QPF amounts between 0.5-1" of QPF in
the band. Moderate mid-level lapse rates (in excess of 6.5
degC/km) and negative saturated EPV values further suggest
favorable conditions for banded precip.

The question then becomes...is this precip falling as rain or
snow? Temps will gradually be falling into the 30s after 9 PM
Sat, and current fcst soundings suggest a changeover could occur
at PIA between 10 PM and midnight, with the change at BMI
occurring between 11 PM and 1 AM. This is still within or very
close to the timeframe when the banded ascent is occurring. Given
the marginal thermodynamics and warm ground from the past week,
snow-to-liquid ratios (SLRs) are likely to be less than 10:1
during this time, with any snow that develops being of the heavy,
wet variety.

While I`d like to confidently say that the warm ground temps will
limit accumulations to grassy surfaces, this set up is reminiscent
of an event that occurred south of I-70 in late Nov/early Dec of
2024 and resulted in 1-3" snow totals. Deterministic model
snowfall output is producing unrealistic amounts, with some models
as high as 7-10" of snow within the band. However, the snow depth
field from these same models looks much more reasonable. This
field factors in melting and compaction, and is therefore more
representative of what you`d actually go out and measure on the
ground after an event in a marginal thermodynamic environment like
this. The snow depth field depicts a narrow band of snow amounts
between a dusting to 2", again primarily north of I-74 and in a
band that`s only about 20-30 miles wide. The 08.00z HREF probs
line up well with this analysis, showing a narrow corridor from
Galesburg to Watseka of 10-15% chance of 2" of snow through 6 AM
Sun.

In terms of impacts, the HREF suggests peak snow rates of
0.50-0.75" per hour, which when combined with 25-30 mph wind
gusts out of the northwest would limit visibility (less than 1
mile at times). The progressive nature of the system means that
these peak rates are unlikely to last at any one location for more
than an hour or two. The fact that these conditions would be
occurring overnight on a weekend, and not during a heavy commuting
time, should also help limit impacts to some degree.

*** SUNDAY - MONDAY ***

Raw conditions are expected through Monday, as the aforementioned
upper low over the James Bay transition into a highly anomalous
upper trough over the Midwest. Our Saturday night low will lift
northeast while sfc high pressure develops over the central CONUS,
resulting in persistent, breezy NW flow (gusting 25 to 35 mph on
Sunday). High temps will struggle to reach the mid 30s to low 40s
both days. Wind chill values will stay below freezing through the
day on Sunday, with the coldest values occuring early Monday
morning (around 10 degF).

A few flurries or scattered snow showers are possible (20-40%
chnc) through Sun night, with the best chance being Sun AM when
the wind direction is oriented most favorable for lake-enhanced
precip to reach the ILX CWA. Areas near/east of I-57 stand the
best chance of seeing the lake-enhanced snow showers on Sun. Given
the much colder airmass in place at this point, SLRs will be
higher (between 10:1 and 15:1) meaning any snow that does occur
will be closer to being classified as `fluffy` than `wet/heavy`.
Accumulation potential is low, with areas north of a Bloomington-
Danville line having a 20-30% chance of 1" (per the NBM) and less
than a 20% chance elsewhere.

*** REST OF THE WEEK ***

Aside from some lingering flurries on Monday, primarily dry
conditions are favored through the rest of the week with warming
temps. The upper pattern remains highly amplified, with an upper
ridge over the Rockies progged to shift over the Midwest by late
week. Temps moderate to near normal by Wednesday, with above
normal temps by Friday into next weekend. There is a strong signal
(60-90% chance) for temps at least 10 degF above normal next
weekend, with normal temps featuring highs in the low 50s and lows
near freezing. Precip chances are below 10% each day Tues-Fri.

Erwin

&&

.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 449 AM CST Sat Nov 8 2025

The daytime hours should be VFR with broken mid/high level clouds
and light/variable winds. A sfc low will track directly across the
area this evening, resulting in rain - which could change to snow
at some point between 05-12z. Ceilings are expected to drop to at
least low MVFR tonight, with a decent chance of falling to IFR.
If rain does change to snow, visbys could drop to 1 mile. Included
a PROB30 at the northern terminals for this potential. Precip
will be coming to an end from west to east towards the end of the
period. Breezy northwest winds develop overnight, with gusts to
around 25 kts possible.

Erwin

&&

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

$$