229
FXUS63 KILX 241033
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
533 AM CDT Thu Sep 24 2026

.KEY MESSAGES...

- Quiet weather will prevail for the next several days before a
  pattern change brings unsettled conditions and the potential
  for thunderstorms by the middle of next week.

&&

.DISCUSSION...
Issued at 329 AM CDT Thu Sep 24 2026

Despite the presence of a sprawling ridge of high pressure
extending from Quebec to the southern Plains, central Illinois
remains locked in overcast conditions early this morning.
Persistent boundary layer moisture continues to be trapped
beneath a strong subsidence inversion and the E/NE low-level
flow is doing little to nothing to help scour it out.
Unfortunately with the overall synoptic pattern changing very
little and surface winds expected to maintain an easterly
component, prospects for widespread/lasting clearing remain dim
through the upcoming weekend.

As an upper low evident on 07z/2am water vapor imagery over the
Appalachians tracks slowly eastward and deepens, it will serve
as an effective block to any systems crossing the central U.S.
through the weekend. An initial short-wave trough across the
Dakotas will lift northeastward over the next 24-36 hours. The
tail end of this feature will bring weak synoptic lift into the
western KILX CWA tonight into Saturday. While deep-layer
moisture will be limited, most models suggest widely-scattered
light showers developing in the Illinois River Valley.

Once the first wave passes well to the north, a stronger wave
currently over Baja California will approach from the southwest
on Saturday. This feature will weaken as it approaches an upper
ridge locked in place along/east of the Mississippi River:
however, it appears a few showers could spread as far east as
I-55...especially Saturday night into early Sunday before the
wave dissipates.

00z Sep 24 synoptic models are in excellent agreement through 96
hours (00z Mon), then solutions diverge significantly next week.
All models show a high-amplitude wave coming onshore along the
West Coast on Sunday: however, both the ECMWF and GEM further
amplify the wave into a closed low over the Desert Southwest
Monday-Wednesday, Meanwhile the GFS and GFS Ensemble maintain a
more progressive open wave that quickly traverses the country
and swings into central Illinois Wednesday into Thursday.
Current teleconnections forecast from both the deterministic
ECMWF and GFS suggest the AO and NAO will become negative early
next week, which is supportive of an amplified pattern. Exactly
how amplified remains in question at this point. Current NBM
features rain chances arriving as early as Tuesday. If the
slower/more amplified ECMWF/GEM verify, precip will likely be
delayed until Wednesday...then may linger through the end of the
week as the wave only slowly approaches from the southwest. At
this point, expect a benign forecast across central Illinois
through the weekend with temperatures climbing well into the
70s/lower 80s by Monday/Tuesday. After that, things will become
more unsettled and thunderstorm chances will return to the
picture at some point during the Tuesday through Friday time
period.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 533 AM CDT Thu Sep 24 2026

1015z/515am satellite imagery shows overcast conditions across
the majority of central Illinois: however, breaks have developed
along/north of a KBMI to KMQB line. Based on satellite trends
and the latest HRRR/CONSSHORT output, have maintained VFR
ceilings at KPIA through the entire 12z TAF period. Further E/SE
at the remaining terminals, the ceiling forecast is a bit more
challenging. After a period of IFR at KCMI/KDEC during the
evening, ceilings have risen to MVFR at all sites. While ample
low cloud cover is noted upstream across Indiana, models insist
bases will diurnally rise to VFR. Have generally followed the
HRRR forecast, resulting in a return to MVFR at the rest of the
terminals between 18z and 20z. After that, BKN-OVC VFR clouds
are expected to linger through Friday morning. Winds will remain
NE at 8-12kt.

&&

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

&&

$$

KEY MESSAGES...Barnes
DISCUSSION...Barnes
AVIATION...Deubelbeiss