336
FXUS63 KILX 110556
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1256 AM CDT Thu Jun 11 2026

.KEY MESSAGES...

- Widespread heat continues through Thursday, though increasing
  cloud cover keeps the chance of heat index values exceeding
  100 degrees at around 20 percent south of Interstate 72.

- Thunderstorms will push across central Illinois this
  evening...bringing a risk for damaging wind gusts and
  localized flash flooding.

- A cold front brings another round of severe storms Thursday
  evening and overnight, where damaging straight-line winds
  remain the main concern.

&&

.UPDATE...
Issued at 906 PM CDT Wed Jun 10 2026

Showers and storms continue as forecasted and overall, the
current forecast still looks good on timing of storms moving
across the area. However, did decide to clean up pops/wx and
increased them in the southeast late tonight. Also increased qpf
for tonight and overnight some. Remainder of the forecast for
temps and winds looks fine and will not plan to update the rest
of the night.

New update should be out shortly.

&&

.DISCUSSION...
Issued at 1246 PM CDT Wed Jun 10 2026

Short Term Forecast: Heat and Severe Potential

Today and tomorrow will feature widespread temperatures in the
90s, with heat indices climbing into the upper 90s to lower
100s. Confidence in meeting Heat Advisory criteria (max heat
index near 105F) remains low; LREF probabilities for heat
indices exceeding 100F generally hold around 20 percent for
areas south of I-72. Primary limiting factors for higher heat
readings will be increasing cloud cover and precip chances along
with convective debris, particularly on Thursday for the
latter.

Thunderstorms are ongoing early this afternoon across portions
of eastern Iowa and northeastern Missouri, with additional
development expected to our west later this evening. Out ahead
of the initial convective line, temperatures pushing 90 degrees
and dew points in the low to mid-70s are supporting roughly
1500-2000 J/kg of weakly capped MLCAPE across central Illinois.
Instability will further increase through mid-afternoon, peaking
near 2500 J/kg. Effective bulk shear values will increase to
around 30kt with the arrival of storms, sufficient to support an
organized severe threat.

This initial line of storms is expected to lift northeast,
likely staying near or just north of the I-72 corridor. While
low-level flow is currently veered with unimpressive SRH values,
this is forecast to increase ahead of the second line of
storms. DCAPE values around 900-1200 J/kg, coupled with
increasingly steep low-level lapse rates, will support a wind
threat with the first wave of convection. Round two will see
strengthened kinematic fields as storms congeal into a line and
spread ESE across central Illinois late this evening. Damaging
winds will remain the primary threat, though interactions with
remnant outflow boundaries and increasing low-level winds
associated with a strengthening low-level jet will support a
localized tornado threat this evening. This threat will slowly
subside with waning diurnal instability as the system moves east
overnight.

In addition to the severe potential, multiple rounds of storms--
including the possibility for backbuilding and training--pose a
localized flooding threat. Corfidi vectors ahead of the second
line of storms drop below 10 kt and become oriented out of the
northeast, suggesting potential for backbuilding along the
southern periphery of the QLCS. While the severe threat should
diminish overnight, the hydro threat may linger well into or
through the overnight hours.

Thursday and Extended Period
A robust shortwave trough is expected to lift into the Upper
Midwest on Thursday, driving a cold front through central
Illinois Thursday evening and overnight. Ahead of this boundary,
the GFS suggests a broad, unstable warm sector with MLCAPE
values exceeding 3000 J/kg. Coupled with deep-layer shear of
25-35 kt and 0-1km shear of 15-25 kt, the kinematic environment
remains seasonably strong Thursday. While pre-frontal discrete
activity with all severe hazards is possible, the primary
concern remains straight-line winds as convective elements
congeal into a line along and ahead of the front.

Lingering showers and storms over southeast Illinois on Friday
morning will exit quickly, giving way to clearing skies as high
pressure builds into the region. This will provide a brief
return to more seasonal conditions, with highs in the lower to
mid-80s and dew points mixing down into the upper 50s, resulting
in a much more comfortable air mass.

For the weekend and into early next week, the pattern turns
more zonal aloft while a low-level baroclinic zone wobbles over
the region. This setup maintains additional chances for showers
and thunderstorms, though specifics regarding timing and
coverage remain uncertain at this forecast range.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1255 AM CDT Thu Jun 11 2026

Rain and scattered embedded storms are still ongoing around most
of the sites, except PIA and BMI. Will continue either VCTS or a
TEMPO group for SPI, DEC, and CMI for another 3-4 hrs overnight.
All sites should be dry for late tonight and through the morning
hours. Then another round of storms will be possible late
tomorrow afternoon through early tomorrow evening. Have already
placed TEMPO groups for all sites for thunderstorms. Winds will
become breezy tomorrow afternoon as well ahead of the storms.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 7 AM CDT this morning for ILZ027>031-036>038-
040>043-047>051.

&&

$$

KEY MESSAGES...Deubelbeiss
UPDATE...Auten/Erwin
DISCUSSION...Barnes
AVIATION...Auten