069
FXUS63 KILX 221915
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
115 PM CST Sat Nov 22 2025

.KEY MESSAGES...

- There is a greater than 90% chance for rain Monday evening and
  overnight. 25th-75th percentile rainfall amounts range from
  0.10-0.40 in the northwestern counties to 0.25-0.75 in the
  southeast.

- Above normal temperatures through Tuesday will turn sharply
  colder midweek with widespread low to mid 20s in the forecast
  Thursday morning.

&&

.DISCUSSION...
Issued at 109 PM CST Sat Nov 22 2025

This afternoon, a ridge of high pressure extends from the eastern
Great Lakes across the mid Mississippi Valley into the southern
Great Plains. Further north, low pressure is tracking east into
Ontario while a trailing cold front stretches south into the Upper
Midwest. Locally, southwest winds will freshen ahead of the front
late this evening, then will veer to a northwesterly direction
overnight behind the front. No precip is expected with frontal
passage. Winds drop off again late tonight behind the front as
high pressure builds back into the region. This may allow enough
time for fog to form once again, especially near the lower
Illinois River Valley. Sunday will be sunny with light winds under
the influence of high pressure.

Meanwhile, a closed upper low over SoCal today is progged to lift
into the central Great Plains Sunday night then across central
Illinois late Monday as the wave opens up. A weak surface
reflection will eject from the Front Range of the Rockies Sunday
night, tracking east across Kansas City Monday evening. Ahead of
the low, warm air advection will drive the next round of precip
across central Illinois late Monday afternoon through Monday night
with additional showers possible late Monday night into Tuesday
morning with passage of the upper wave. A few embedded convective
elements appear possible with very weak but non-zero elevated
CAPE values rooted around 700mb, but forecast soundings show the
depth of the instability may not be sufficient to allow
thunderstorms. NBM mean QPF ranges from roughly a third of an inch
in the NW CWA to around half an inch in the SE. 25th-75th
percentile values range from 0.10-0.40 near Galesburg to
0.25-0.75 near Lawrenceville. A few isolated (10%) swaths of just
over an inch are possible for any embedded convection that
develops with this chance greatest along and south of I-70.

A fast moving northern stream wave will be right behind our early
week system and will result in a deepening low over the Upper
Midwest and western Great Lakes late Tuesday into Wednesday. A
strong cold front will push across central Illinois Tuesday night.
Precip looks to stay very limited in both probabilities (30%) and
amounts (<0.10 in) but a big swing in temperatures is likely.
Highs on Tuesday ahead of the front will top out in the upper 50s
to mid 60s, but by Wednesday night behind the front, temps will
fall into the 20s area-wide, ushered in by strong west/northwest
winds gusting up to around 35 mph. Highs will generally range in
the upper 30s to mid 40s through the second half of the
week.

Deubelbeiss

&&

.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1120 AM CST Sat Nov 22 2025

VFR conditions will persist through much of this TAF period,
though we are monitoring a narrow patch of stratus moving in from
the north ahead of a cold front. Ceilings within this stratus
patch have largely been around 6-10 kft.

Surface winds will shift from west to northwest near or just
after 06z as a weak cold front drops across the regional
terminals. Some patchy fog cannot be ruled out late tonight into
Sunday morning. Confidence is currently reasonably high enough to
include a TEMPO group for reduced visibility and lower ceilings as
winds relax behind the front.

MJA

&&

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

$$