776
FXUS63 KILX 051046
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
546 AM CDT Fri Jun 5 2026

.KEY MESSAGES...

- Thunderstorm development tonight carries high uncertainty
  near and north of Interstate 72. If storms manage to form,
  they will pose a primary risk of large hail and damaging wind
  gusts.

- Expect a warm and humid weekend with feel-like temperatures
  climbing into the low 90s. The overall severe weather threat
  through Sunday remains minimal.

- A stronger warming trend arrives Wednesday through Friday of
  next week, pushing heat index values near 100 degrees. There
  is currently less than a 20% chance for rain to interrupt the
  heat.

&&

.DISCUSSION...
Issued at 235 AM CDT Fri Jun 5 2026

Showers and thunderstorms currently situated over portions of
Missouri and Iowa are expected to persist and advance eastward
through late morning, sustained by a subtle mid-level shortwave
and a 40-knot low-level jet traversing the mid-Mississippi
Valley. This convective activity should taper off by early
afternoon as the shortwave exits to the east and the low-level
jet weakens.

The focus then shifts to later this evening as a residual
outflow acts as the effective boundary for renewed storm
potential across northern Missouri or southern Iowa. Although
CAM guidance remains inconsistent regarding storm initiation due
to moderate capping and a lack of strong synoptic forcing, an
increasingly buoyant environment is expected as an EML and
steepening mid- level lapse rates overspread the region.
According to latest HREF Mean guidance, MUCAPE values near 2000
J/kg will persist through the overnight hours for areas near
and north of the I-72 corridor. The combination of subtle low-
level jet forcing and shortwave energy moving through the mid-
Mississippi Valley tonight may provide sufficient lift for
parcels to reach the LFC. However, the forecast hinges on
whether an additional stable layer above the LFC is formidable
enough to suppress updrafts; if yes, activity will be minimal,
but if no, the environment will support a risk of large hail
and sporadic damaging wind gusts.

While flash flooding is not currently a primary concern due to
high forecast uncertainty, dry antecedent conditions, and
progressive Corfidi vectors that discourage training storms, it
cannot be entirely ruled out. High PWATs remain in place, and
HREF PMM QPF suggests that isolated areas could still see
rainfall totals exceeding 2 inches through tonight.

By Saturday and Sunday, an upper-level ridge will allow a warm,
very humid air mass to build in, potentially triggering further
thunderstorm activity. Although a diffuse surface boundary
draped across the forecast area may serve as a focal point for
scattered afternoon storms, the severe weather threat this
weekend appears minimal due to lackluster deep-layer shear and
poor mid-level lapse rates. The bigger weather story this
weekend will be the low 90s feel-like temps.

The upper ridge axis is projected to shift east of the area by
Monday and Tuesday, making way for a negatively-tilted trough
and multiple shortwaves traveling from the lower-Missouri Valley
into central Illinois. This setup brings renewed chances for
showers and thunderstorms. While increasingly humid and unstable
air will be present, typical seasonal limitations such as weak
kinematics and mediocre lapse rates are expected to persist.
Consequently, the forecast suggests a largely dry pattern
punctuated by scattered, potentially strong thunderstorms.

Looking toward the middle and end of next week, blended NBM
guidance indicates a stronger warming trend as a 588-mb ridge
establishes itself over the Midwest. Temperatures are currently
forecast to reach the low-to-mid 90s, with heat indices nearing
100 degrees from Wednesday through Friday. Although the NBM
includes slight (20%) precipitation chances during this
timeframe, significant mid- level capping will likely inhibit
robust updraft development.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 529 AM CDT Fri Jun 5 2026

An area of decaying showers and thunderstorms will continue to
push across the central Illinois terminals this morning, perhaps
drying up before reaching KCMI. Short-term model guidance has
been steadfast in this activity diminishing, and so the TAFs
have maintained a PROB30 group for TSRA/SHRA rather than a
predominant mention due to confidence and coverage concerns at
any one terminal.

Otherwise, winds will remain from the S/SW today, occasionally
gusting to 25 kts.

Additional showers and thunderstorms may develop overnight into
Saturday morning. Once again, forecast certainty is low enough
to exclude predominant TSRA at any one site; and have instead
opted for a blanket PROB30 group staggered across the regional
terminals late in the TAF period.

&&

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

&&

$$

KEY MESSAGES...MJA
DISCUSSION...MJA
AVIATION...MJA