Damaging Winds in Illinois, May 16, 2026

Area Forecast Discussion
National Weather Service Lincoln IL
246 AM CDT Sat May 16 2026

.KEY MESSAGES...

- Periods of thunderstorms will track across central Illinois
  today, bringing a marginal risk (Level 1 of 5) for 60 mph
  wind gusts and golf ball-sized hail.

- Slow-moving storms will bring a risk of localized flooding
  today, producing isolated rainfall totals of 3 to 4 inches in
  east-central or southeast Illinois.

- A separate, much stronger storm system will bring a threat of
  organized, high-impact severe weather to the area in the
  Monday-Tuesday timeframe.

- A moderate heat risk will persist through Tuesday,
  particularly impacting individuals sensitive to high
  temperatures or those lacking sufficient cooling and
  hydration.

&&

.DISCUSSION...
Issued at 243 AM CDT Sat May 16 2026

A complex mesoscale environment is unfolding across the Midwest
this morning. Regional radar mosaics highlight a pair of
outflow boundaries currently sagging into Central Illinois,
downstream of decaying convection over Iowa. To the west, a pair
of shortwave troughs positioned over north-central Missouri and
southeast Nebraska are progged to traverse the local area later
this morning into the early afternoon. Supported by a modest
low-level jet (LLJ), these features will encounter a
sufficiently buoyant airmass characterized by MUCAPE values in
the 2500-3000 J/kg range.

Expect convection to blossom across portions of central
Illinois later this morning and throughout the afternoon. While
the ripples in the flow may provide some local enhancement to
deep-layer shear, values are generally expected to remain around
30 kts or less. This should limit the potential for widespread
organized severe weather; however, a Marginal Risk (Level 1 of
5) remains in place. The primary threats with the more robust
cores will be isolated damaging wind gusts up to 60 mph and
large hail up to the size of golf balls.

Of additional concern is the potential for localized hydro
issues. With slow-moving convective outflows and a high-moisture
environment, training or backbuilding cells could produce heavy
rainfall. The 00z HREF LPMM QPF indicates a signal for 3-4 inch
totals, particularly over east-central or southeast Illinois, a
trend supported by recent HRRR runs.

Central Illinois will remain firmly entrenched in the warm
sector through the remainder of the weekend. Humid conditions
will persist with temperatures climbing into the mid-80s. While
zonal mid-level flow and subtle shortwaves may trigger isolated
to widely scattered showers and storms, the lack of robust deep-
layer shear (generally less than 30 kts) will keep the severe
threat disorganized and low-impact.

The synoptic focus shifts significantly toward the Monday-
Tuesday timeframe as a potent upper-level wave pivots out of the
Great Basin and lifts into the Northern Plains. An associated
cold front will sweep into the Mid-Mississippi Valley,
encountering a highly unstable environment with MLCAPEs
exceeding 2500 J/kg. Unlike the weekend activity, this system
will be accompanied by a notable increase in kinematic support,
with deep-layer shear increasing into the 30-40 kt range. This
environment is conducive to organized, high-impact severe
weather, and this period will need to be monitored closely for
potential upgrades in risk categories.

Model consistency begins to diverge slightly by mid-week
regarding the timing of the frontal passage. Should the front
slow, lingering moisture and instability could support re-
development on Wednesday, likely confined to areas along and
south of the I-70 corridor. By Thursday and Friday, a transition
to a cooler and more stable post-frontal regime is anticipated
as high pressure begins to build into the region. Mid-range
deterministic guidance does show semblance of another frontal
passage in the Friday-Saturday timeframe, but moisture return
ahead of the front looks too poor to support appreciable rain
chances then, at least for now.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1246 AM CDT Sat May 16 2026

Scattered tsra expected to develop after 10Z-12Z, continuing
through morning hours, and have included PROB30 for tsra with
MVFR vsby for this activity. While not included in TAFs, briefly
worse conditions possible in storms. Predictability of storms
later in the day is too low for mention in TAFs, but there
remains a low chance for storms the remainder of the 24 hour TAF
forecast period. Low level wind shear will continue through much
of the night from KSPI-KBMI eastward due to a SW 40 kt wind
aloft. Otherwise, surface winds S 10-12 kts overnight, with
gusts to around 20 kts developing by 18Z for most of the area.
Gusts decreasing after 00Z.

&&

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

&&

KEY MESSAGES...MJA
DISCUSSION...MJA
AVIATION...37

Hazardous Weather Outlook
National Weather Service Lincoln IL
354 PM CDT Fri May 15 2026

ILZ027>031-036>038-040>057-061>063-066>068-071>073-162100-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-Logan-De Witt-Piatt-Champaign-Vermilion-Cass-Menard-Scott-
Morgan-Sangamon-Christian-Macon-Moultrie-Douglas-Coles-Edgar-Shelby-
Cumberland-Clark-Effingham-Jasper-Crawford-Clay-Richland-Lawrence-
354 PM CDT Fri May 15 2026

This Hazardous Weather Outlook is for central Illinois, east
central Illinois, southeast Illinois and west central Illinois.

.DAY ONE...Tonight.

Thunderstorms are possible late tonight across portions of central
Illinois, mainly west of I-57. Widespread severe weather is not
expected with any of these storms; but there is a marginal risk that
some of the storms could become severe, with hail up to 1 inch and
damaging wind gusts up to 60 mph the main threats.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

There is a moderate heat risk Sunday and Monday as temperatures warm
well into the 80s. This will primarily affect those who are
sensitive to heat, especially those without cooling or hydration.

Daily severe weather is possible across portions of central Illinois
Saturday through Tuesday, but the Monday and Tuesday period hold the
greatest risk for widespread, high-impact storms.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated tonight.

Deubelbeiss

Special Weather Statement
National Weather Service Lincoln IL
440 AM CDT Sat May 16 2026

ILZ027-028-161000-
Knox-Stark-
440 AM CDT Sat May 16 2026

...A STRONG THUNDERSTORM WILL IMPACT STARK AND NORTHEASTERN KNOX
COUNTIES THROUGH 500 AM CDT...

At 440 AM CDT, Doppler radar was tracking a strong thunderstorm over
La Fayette, or near Toulon, moving east at 55 mph.

HAZARD...Wind gusts up to 50 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Wyoming, Toulon, Osceola, Bradford, Elmira, Victoria, La Fayette,
Castleton, and West Jersey.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4098 8964 4102 9015 4115 9013 4115 8987
      4123 8986 4124 8964
TIME...MOT...LOC 0940Z 267DEG 50KT 4111 8998

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH

37