Tornado Warning 71, NWS Chicago, IL

939 
WWUS53 KLOT 111537
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
1037 AM CDT Tue Aug 11 2026

ILC063-093-111546-
/O.CAN.KLOT.TO.W.0071.000000T0000Z-260811T1630Z/
Kendall IL-Grundy IL-
1037 AM CDT Tue Aug 11 2026

...THE TORNADO WARNING FOR SOUTHEASTERN KENDALL AND NORTHEASTERN
GRUNDY COUNTIES IS CANCELLED...

The tornadic thunderstorm which prompted the warning has  moved out 
of the warned area. Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 200 PM CDT for
northeastern Illinois.

&&

LAT...LON 4121 8753 4120 8824 4151 8825 4149 8779
      4147 8779 4147 8753
TIME...MOT...LOC 1536Z 270DEG 54KT 4136 8815 

$$

ILC091-197-111630-
/O.CON.KLOT.TO.W.0071.000000T0000Z-260811T1630Z/
Will IL-Kankakee IL-
1037 AM CDT Tue Aug 11 2026

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1130 AM CDT FOR WILL AND
NORTHEASTERN KANKAKEE COUNTIES...

At 1036 AM CDT, a severe squall line capable of producing both
tornadoes and extensive straight line wind damage was located near
Elwood, or near Wilmington, moving east at 60 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

These dangerous storms will be near...
  Wilmington and Elwood around 1040 AM CDT.
  Manhattan around 1045 AM CDT.

Other locations in the path of this tornadic thunderstorm include
Peotone, Monee and Beecher.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

This cluster of thunderstorms is capable of producing tornadoes and
widespread significant wind damage. Do not wait to see or hear the
tornado. For your protection move to an interior room on the lowest
floor of a building.

&&

LAT...LON 4121 8753 4120 8824 4151 8825 4149 8779
      4147 8779 4147 8753
TIME...MOT...LOC 1536Z 270DEG 54KT 4136 8815 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Borchardt

792 
WWUS53 KLOT 111543 RRA
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
1043 AM CDT Tue Aug 11 2026

ILC091-197-111630-
/O.CON.KLOT.TO.W.0071.000000T0000Z-260811T1630Z/
Will IL-Kankakee IL-
1043 AM CDT Tue Aug 11 2026

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1130 AM CDT FOR
SOUTHEASTERN WILL AND NORTHERN KANKAKEE COUNTIES...

At 1043 AM CDT, a severe squall line capable of producing both
tornadoes and extensive straight line wind damage was located near
Manhattan, or 8 miles northeast of Wilmington, moving east at 55 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

These dangerous storms will be near...
  Peotone and Monee around 1050 AM CDT.
  University Park around 1055 AM CDT.

Other locations in the path of this tornadic thunderstorm include
Crete and Beecher.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

This cluster of thunderstorms is capable of producing tornadoes and
widespread significant wind damage. Do not wait to see or hear the
tornado. For your protection move to an interior room on the lowest
floor of a building.

&&

LAT...LON 4120 8813 4141 8804 4150 8799 4149 8779
      4147 8779 4147 8753 4121 8753
TIME...MOT...LOC 1543Z 265DEG 49KT 4137 8802 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Borchardt

553 
WWUS53 KLOT 111547
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
1047 AM CDT Tue Aug 11 2026

ILC091-197-111630-
/O.CON.KLOT.TO.W.0071.000000T0000Z-260811T1630Z/
Will IL-Kankakee IL-
1047 AM CDT Tue Aug 11 2026

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1130 AM CDT FOR
SOUTHEASTERN WILL AND NORTHEASTERN KANKAKEE COUNTIES...

At 1047 AM CDT, a severe squall line capable of producing both
tornadoes and extensive straight line wind damage was located near
Monee, or near Peotone, moving east at 55 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

These dangerous storms will be near...
  Peotone, University Park, Monee, and Beecher around 1050 AM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

This cluster of thunderstorms is capable of producing tornadoes and
widespread significant wind damage. Do not wait to see or hear the
tornado. For your protection move to an interior room on the lowest
floor of a building.

&&

LAT...LON 4121 8802 4138 8796 4149 8791 4149 8779
      4147 8779 4147 8753 4121 8753
TIME...MOT...LOC 1547Z 280DEG 63KT 4139 8779 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Borchardt

422 
WWUS53 KLOT 111558
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
1058 AM CDT Tue Aug 11 2026

ILC091-197-111630-
/O.CON.KLOT.TO.W.0071.000000T0000Z-260811T1630Z/
Will IL-Kankakee IL-
1058 AM CDT Tue Aug 11 2026

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1130 AM CDT FOR
SOUTHEASTERN WILL AND NORTHEASTERN KANKAKEE COUNTIES...

At 1057 AM CDT, a severe squall line capable of producing both
tornadoes and extensive straight line wind damage was located near
Crete, or near Steger, moving east at 55 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

This tornadic thunderstorm will remain over mainly rural areas of
southeastern Will and northeastern Kankakee Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

This cluster of thunderstorms is capable of producing tornadoes and
widespread significant wind damage. Do not wait to see or hear the
tornado. For your protection move to an interior room on the lowest
floor of a building.

&&

LAT...LON 4121 8775 4134 8770 4147 8777 4147 8753
      4121 8753
TIME...MOT...LOC 1557Z 265DEG 49KT 4140 8759 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Borchardt

785 
WWUS53 KLOT 111604
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
1104 AM CDT Tue Aug 11 2026

ILC091-197-111613-
/O.CAN.KLOT.TO.W.0071.000000T0000Z-260811T1630Z/
Will IL-Kankakee IL-
1104 AM CDT Tue Aug 11 2026

...THE TORNADO WARNING FOR SOUTHEASTERN WILL AND NORTHEASTERN
KANKAKEE COUNTIES IS CANCELLED...

The portion of the storm which prompted the Tornado Warning has 
moved out of the area. Therefore, the warning has been cancelled.

However, a Severe Thunderstorm Warning remains in effect until 1115 
AM. 

&&

LAT...LON 4121 8775 4134 8770 4147 8777 4147 8753
      4121 8753
TIME...MOT...LOC 1602Z 265DEG 49KT 4141 8747 

$$

Borchardt

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
819 AM CDT Tue Aug 11 2026

.KEY MESSAGES...

- Scattered thunderstorms will affect far northern IL/northwest
  IN early this morning, with isolated instances of large hail
  and damaging wind as well as localized flooding are possible.

- Possible line/complex of severe thunderstorms to affect the
  area by mid/late morning into early this afternoon. Severe
  wind gusts to 80 mph possible, along with heavy rain and
  localized flooding.

- Pattern remains active with additional thunderstorm chances
  through the end of the week/weekend.

&&

.MESOSCALE...
Issued at 819 AM CDT Tue Aug 11 2026

While it took quite some time overnight, the convection over IA
has evolved into a more well organized MCS since 11z. DVN WSR-88D
imagery shows an impressive rear inflow jet has developed with
strengthening cold already resulting in an acceleration of in
forward speed, now moving at around 55 kt.

Morning soundings from ILX and DVN depict a very unstable air
mass in advance of this MCS with steep lapse rates and very
moist boundary layer. While there is still CINH with surface
based parcels, some weakening of this CINH will take place this
morning as sfc warms and dewpoints creep up this morning. Even
with some sfc based CINH, strongly forced ascent on leading edge
of this MCS should have no problem forcing parcels up to the
LFC.

KDMX 88D VWP shows a nice 50kt mid level speed max feeding into
the backside of this MCS, providing ample deep layer shear for
continued mesoscale organization. SPC mesoanalysis depicts an
axis of >3000 J/kg of MLCAPE from northwest IL east-southeast to
west central Indiana. This is in close proximity to a diffuse
surface boundary that remains draped across a very similar area.

Expectation this morning is MCS should continue maintain its
intensity and probably begin to intensify by mid-late morning as
it encounters weaker CINH and diurnally destabilizing boundary
layer. Environment appears primed for a higher-end bow echo and
possible derecho to evolve from this MCS as it rips across our
CWA this morning. Given the orientation of the diffuse sfc
boundary and instability axis, some southward propagation to
this line is likely.

Primary hazard will obviously be damaging winds, potentially
swaths in excess of 80 mph as this complex races across our CWA.
Presence of the weak surface boundary running perpendicular
this QLCS could provide a source of low level vorticity for
mesovortices and potential QLCS tornadoes as well. This threat
is likely to increase as the activity gets into our eastern CWA
as boundary layer destabilizes further.

- Izzi

&&

.DISCUSSION...
Issued at 253 AM CDT Tue Aug 11 2026

Forecast remains complex today, with ongoing storms early this
morning and the potential evolution of a more significant
widespread severe weather/damaging wind threat later this
morning and early afternoon.

Early morning surface analysis depicts a rather diffuse warm
frontal zone stretching from north-central IA east-southeast
across northern IL and northwest IN, roughly from north of the
Quad Cities to LOT and VPZ. KLOT VAD wind profile and SPC/RAP
mesoanalysis indicates a ~25 kt west-southwesterly low level jet
impinging on the frontal zone, with associated isentropic
ascent atop the shallow frontal slope resulting in isolated
thunderstorms from near ARX over to the Lake Michigan shore near
Michigan City IN at this hour. Low-level jet forcing may
increase a bit during the predawn hours as a subtle mid-level
short wave tracks across the area. There has been a signal in
CAM guidance for potential additional development along the
front prior to sunrise, and we continue to monitor for that.
MUCAPE near 3000 J/kg and ~40 kts of effective shear per SPC
mesoanalysis would support storm organization and an associated
severe (primarily wind/hail) threat as evidenced by the
scattered supercell storms currently over LM/IWX's cwa.

Attention then turns to a developing area of thunderstorms over
far southeast South Dakota, which may evolve into a more
widespread and potentially significant severe weather threat
across our forecast area later this morning and early afternoon.
CAM guidance has been consistent in this cluster of storms
eventually growing upscale into a forward-propagating MCS across
northwest IA/southwest MN over the next few hours and
eventually tracking east-southeast along the corridor strong
instability along the aforementioned frontal zone into northern
IL toward mid-late morning. The combination of unseasonably
strong westerly mid-level flow and resulting deep shear(50+ kts
at 700 mb), steep mid-level lapse rates (near 8 C/km) MUCAPE
values in excess of 3500 J/kg, the potential for significant
severe weather appears rather high. Several CAMs are depicting
pockets surface wind gusts of 80+ mph with this MCS across
portions of the forecast area. A tornado threat would also
likely exist given sufficient low-level shear and the proximity
of the previously mentioned surface frontal boundary. While the
exact evolution of this MCS remains uncertain, SPC's Day 1
enhanced (level 3 of 5) for out forecast area appears warranted.
Currently timing of this threat looks to be from perhaps 9 AM
in our northwest cwa through around 3 PM in the far east. There
may also be some convective development along the front ahead of
the MCS, if a strong MCV develops prior to reaching the cwa
increases warm-advection ascent ahead of the main cluster as
indicated by some of the CAMs.

As if the significant severe/widespread damaging wind threat
wasn't enough, we'll also need to monitor the location of heavy
rainfall and flooding potential - particularly for the urbanized
Chicago metro area as well as locations which saw 3-5"+ of
rainfall Sunday and evening. Had contemplated issuing a flood
watch, though with current predawn convection slow to fill-in
(so far) and some uncertainty remaining with the evolution of
the MCS later this morning, elected to hold off at this time
pending some further clarity on location of higher rainfall
impacts.

In the wake of today's expected MCS, a lull in convective
activity is expected from later this afternoon into tonight,
though this will likely depend on the size and magnitude of the
remnant cold pool and how far south the effective frontal zone
ends up along it's southern periphery. The overall pattern some
uncertainty is how far south an area of surface high pressure
builds across the western Lakes in the Friday/Saturday period.
This will have significant impacts on thunderstorm trends/timing
for the local area.

Ratzer

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 706 AM CDT Tue Aug 11 2026

Key Messages:

- An organized complex of thunderstorms is likely to impact the
  terminals between mid-morning and mid-afternoon today. Severe
  wind gusts in excess of 50 kts may occur with these storms.

- Sub-VFR ceilings and visibilities are likely to be observed
  again late tonight into Wednesday morning.

A thunderstorm complex in eastern Iowa at press time is
attempting to get organized into a solid line or bow. These
storms will impact the terminals between mid-morning and mid-
afternoon, and if it manages to become well-organized by the
time it reaches the terminals (observational trends seem to
support that occurring), then severe wind gusts in excess (and
potentially well in excess) of 50 kts may be observed as these
storms roll through. Also could see a few storms develop out
ahead of this main thunderstorm line/bow, so have PROB30 groups
for TSRA preceding the main TEMPO TSRA groups in the Chicago
metro TAFs to account for this possibility.

The persisting abundance of low-level moisture allowed for MVFR
stratus and fog/mist to develop once again last tonight, and
sub-VFR conditions are still being observed at some TAF sites as
of 1200Z. These conditions should improve by mid-morning, but
the persisting low-level moisture and light winds tonight will
likely allow for low stratus and fog to develop once again.

Lastly, there is another chance for thunderstorms to affect the
terminals tomorrow. Current thinking is that the main surface
boundary that storms will focus along tomorrow may remain south
of the terminals, but if this boundary ends up a little farther
north than presently expected, then there will likely be a need
for some sort of TSRA mention to be introduced into the TAFs.

Ogorek

&&

.MARINE...
Issued at 253 AM CDT Tue Aug 11 2026

A potential exists for a severe thunderstorm complex to produce
widespread damaging winds (in excess of 65 knots) across far
southern Lake Michigan later this morning/midday. In addition to
the wind threat itself, the line of storms are expected to
propagate in an east-southeast direction, which could
potentially lead to a seiche (water is pushed ahead of the
storms, then sloshes back and forth for several hours after the
storms pass) on the southern portion of the Lake. If this were
to occur, it could result in fluctuating lake levels along the
Illinois and Indiana shores for a time from later morning into
this afternoon.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

Visit us at weather.gov/chicago

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
344 AM CDT Tue Aug 11 2026

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-120845-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
344 AM CDT Tue Aug 11 2026 /444 AM EDT Tue Aug 11 2026/

This Hazardous Weather Outlook is for portions of north central
Illinois...northeast Illinois and northwest Indiana.

.DAY ONE...Today and Tonight.

Weather hazards expected...

  Significant Thunderstorm Risk...with an associated:
     Level 1 of 5 Tornado Risk.
     Level 3 of 5 Damaging Wind Risk...up to 80 mph.
  Elevated Flooding Risk.

DISCUSSION...
Scattered thunderstorms early this morning will present a
localized risk of severe weather, primarily damaging winds. A
complex of thunderstorms may then move across the area from mid-
morning into early this afternoon. If this complex materializes,
it will likely be severe with damaging wind gusts as high as 80
mph. In addition, any of these thunderstorms will be capable of
producing torrential downpours which may lead to localized
flooding.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Wednesday and Thursday...
  Elevated Flooding Risk.
  Elevated Thunderstorm Risk...with an associated:
     Level 1 of 5 Severe Thunderstorm Risk.
Friday...
  Elevated Flooding Risk.
  Limited Thunderstorm Risk.
Saturday...
  Limited Flooding Risk.
  Limited Thunderstorm Risk.
Sunday...
  Limited Thunderstorm Risk.

DISCUSSION...

An active and potentially stormy weather pattern will persist
through the end of the week, with additional rounds of
thunderstorms possible and an attendant risk of severe weather
and flash flooding.

.SPOTTER INFORMATION STATEMENT...

  Spotters will likely be needed this morning through mid-
  afternoon.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the east-southeast at 30 to 40 mph. If a bowing
  complex develops, it could move east at 50 to 65 mph.

LMZ740>745-120845-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
344 AM CDT Tue Aug 11 2026

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Today and Tonight.

Weather hazards expected...

  Significant Thunderstorm Risk...with an associated:
     Level 3 of 5 Thunderstorm Wind Gust Risk...up to 70 knots.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Wednesday...
  Limited Thunderstorm Risk.
Thursday and Friday...
  Hazardous conditions for small craft are likely.
  Limited Thunderstorm Risk.
Saturday and Sunday...
  Limited Thunderstorm Risk.

Ratzer

Visit us at www.weather.gov/chicago

Preliminary Local Storm Report
National Weather Service Chicago IL
941 AM CDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0932 AM     Hail             Cedar Lake              41.37N 87.44W
08/11/2026  M0.88 Inch       Lake               IN   Trained Spotter

&&

sb

Preliminary Local Storm Report
National Weather Service Chicago IL
1005 AM CDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0954 AM     Tstm Wnd Gst     3 WNW Troy Grove        41.49N 89.13W
08/11/2026  M55 MPH          La Salle           IL   Public

            Private weather station: 3.7 WNW Troy Grove.

&&

sb

Preliminary Local Storm Report
National Weather Service Chicago IL
1007 AM CDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1000 AM     Tstm Wnd Gst     3 ENE Triumph           41.51N 88.97W
08/11/2026  M53 MPH          La Salle           IL   Public

            Private weather station: 6.1 SSW Earlville.

&&

sb

Preliminary Local Storm Report
National Weather Service Chicago IL
1022 AM CDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1011 AM     Tstm Wnd Gst     2 WNW Sugar Grove       41.77N 88.48W
08/11/2026  M85 MPH          Kane               IL   ASOS

            KARR - Aurora / Sugar Grove Airport.

&&

sb

Preliminary Local Storm Report
National Weather Service Chicago IL
1024 AM CDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1018 AM     Tstm Wnd Gst     2 SE Yorkville          41.62N 88.43W
08/11/2026  M64 MPH          Kendall            IL   Public

&&

sb

Preliminary Local Storm Report
National Weather Service Chicago IL
1025 AM CDT Tue Aug 11 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1015 AM     Tstm Wnd Gst     2 ENE Marseilles        41.34N 88.66W
08/11/2026  M53 MPH          La Salle           IL   Public

            Private weather station: 1.8 ENE Marseilles.

&&

sb