679
FXUS63 KILX 120516
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1216 AM CDT Wed Aug 12 2026

.KEY MESSAGES...

- Scattered thunderstorms will track along and northeast of a
  Lincoln to Paris line through 6pm this evening. A few of the
  cells will be capable of producing gusty winds and large hail.

- There is a Slight Risk (level 2 of 5) for severe weather on
  Wednesday. It appears another storm complex will develop
  across Iowa late tonight, then track southeastward across
  central Illinois from late morning through the afternoon.
  Damaging wind gusts and isolated tornadoes will be the primary
  hazards.

&&

.DISCUSSION...
Issued at 245 PM CDT Tue Aug 11 2026

**** Scattered Storms This Afternoon ****

The severe thunderstorm complex that rolled across northern
Illinois this morning has pushed an outflow boundary southward
to the I-74 corridor this afternoon. As expected, scattered
thunderstorms are developing along this boundary. The atmosphere
across central Illinois is presently moderately unstable
(MLCAPEs 2000-3000J/kg), but weakly capped thanks to very warm
air aloft. The RAP shows the cap gradually weakening as the
afternoon progresses and MLCAPEs increasing to around 4000J/kg
along/east of the I-57 corridor after 21z/4pm. As a result,
think the narrow line of storms currently ongoing along a
Hoopeston to Bellflower line will intensify as it drops
southeastward...posing a risk of marginally severe wind and
hail. Will continue to monitor cells between Peoria and
Bloomington as well, but think the main location for a few
wind/hail reports through 6pm will be along/northeast of a
Lincoln to Paris line.


**** Storm Complex on Wednesday ****

After a mostly quiet night, a short-wave trough ejecting out of
the Rockies will trigger another cluster of thunderstorms
across Iowa late tonight into Wednesday morning. With the
effective boundary pushed a bit further south than it has been
over the past few days, it appears these storms will take a more
southerly route E/SE across the heart of central Illinois. CAMs
exhibit a high degree of variability, so confidence in the
exact location/timing of the storms remains low. Given the
prevailing synoptic pattern and a persistence forecast, think
the 12z RRFS offers the most likely scenario...taking storms
into the Illinois River Valley by late morning, then further
east across the rest of the area during the afternoon.

The environment feeding into the storm complex will not be as
unstable or sheared as today`s scenario across northern
Illinois. The 12z HREF suggests ensemble mean SBCAPEs of
2000-2500J/kg (rather than the 3000-4000J/kg from today), while
the GFS/NAM generally show 0-6km bulk shear of 25-35kt. These
parameters are certainly supportive of strong to severe
convection: however, am not anticipating the same magnitude of
today`s storms to the north. Instead think damaging wind gusts
of 60-70mph, hail larger than quarters, and isolated tornadoes
will be the main hazards.


**** Additional Storm Chances Through Friday ****

The latest SPC Day 3 Convective Outlook highlights central
Illinois with a Marginal Risk (level 1 of 5) on Thursday. With
the boundary still wavering in the immediate vicinity,
additional storm clusters will form and track across the region
Wednesday night through Thursday night. Given an overall
decrease in deep-layer shear, the severe risk will gradually
wane as well. Gusty winds, hail, and locally heavy downpours
will be likely on Thursday. After that, the prevailing upper
ridge currently centered over the Desert Southwest will shift
into the lower Mississippi River Valley by the end of the week.
With rising upper heights, the surface frontal boundary will get
shunted back northward and storm chances will decrease by Friday
and Saturday.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1216 AM CDT Wed Aug 12 2026

Near-term guidance continues to show a thunderstorm complex moving
through parts or all of central IL from late Wednesday morning into
the afternoon hours. Because large uncertainty in storm coverage
exists, held onto the PROB30 groups at all terminals for this cycle.
Outside of this, patchy MVFR fog could develop early this morning,
favoring areas near and north of I-74. 8-10 kt southwest winds will
be in place most of the period, becoming sporadic with any storms,
then becoming east-southeasterly and light by Wednesday evening.

&&

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

&&

$$

KEY MESSAGES...Barnes
DISCUSSION...Barnes
AVIATION...NMA