Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 80, NWS Chicago, IL

August 11, 2021DuPage County, Kane County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Aug 11, 2021, 8:57 PM CDT for DuPage County, Kane County, Illinois. It was in force for 48 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 11, 2021, 8:57 PM CDT (01:57 UTC)
Expired: Aug 11, 2021, 9:45 PM CDT
In force: 48 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

Counties DuPage County, IL, Kane County, IL

The radar

The Chicago radar (KLOT), 29 km from the middle of the area, began a volume at 01:56 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
Aug 11, 9:32 PM CDT	TSTM WND GST 56	Dupage Airport, IL	ASOS STATION KDPA DUPAGE AIRPORT REPORTS 56 MPH GUST.
Aug 11, 9:38 PM CDT	TSTM WND DMG	1 Wsw West Chicago, IL	LARGE TREE DOWNED IN WEST CHICAGO. TIME ESTIMATED BY RADAR.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 11, 8:22 PM CDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 2.0 hours before the alert went out and 190 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 3462 J/kg
Mixed-layer CIN: -49 J/kg
Mixed-layer LCL: 1034 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 103 m²/s²
0-3 km storm-relative helicity: 233 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

803 
WUUS53 KLOT 120157
SVRLOT
ILC043-089-120245-
/O.NEW.KLOT.SV.W.0080.210812T0157Z-210812T0245Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Chicago/Romeoville
857 PM CDT Wed Aug 11 2021

The National Weather Service in Chicago has issued a

* Severe Thunderstorm Warning for...
  Southern Kane County in northeastern Illinois...
  DuPage County in northeastern Illinois...

* Until 945 PM CDT.

* At 856 PM CDT, a severe thunderstorm was located near Sugar Grove,
  or 9 miles west of Batavia, moving east at 40 mph.

  HAZARD...60 mph wind gusts and penny size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Aurora, Naperville, Bolingbrook, Wheaton, Downers Grove, Lombard,
  Bartlett, Carol Stream, Hanover Park, Addison, Glendale Heights,
  St. Charles, Woodridge, Glen Ellyn, West Chicago, Batavia, Geneva,
  Campton Hills, Oak Brook and Westmont.

Including the following interstates...
 I-55 near mile marker 273.
 I-88 between mile markers 102 and 136.
 I-290 between mile markers 5 and 10.
 I-355 between mile markers 15 and 30.

This includes...  Aurora University, Benedictine University, College
of DuPage, DuPage County Fairgrounds, Fermilab, IL Math and Science
Academy, Kane County Cougars Ballpark, Morton Arboretum, Waubonsee
Community College, Wheaton College, and North Central College.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4173 8797 4172 8860 4191 8860 4199 8827
      4199 8798
TIME...MOT...LOC 0156Z 266DEG 33KT 4181 8848 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Petr

3 follow-up statements

810 
WWUS53 KLOT 120209
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
909 PM CDT Wed Aug 11 2021

ILC043-089-120245-
/O.CON.KLOT.SV.W.0080.000000T0000Z-210812T0245Z/
Kane IL-DuPage IL-
909 PM CDT Wed Aug 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 945 PM CDT
FOR SOUTHERN KANE AND DUPAGE COUNTIES...

At 909 PM CDT, a severe thunderstorm was located near Sugar Grove, or
near Batavia, moving east at 30 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Aurora, Naperville, Bolingbrook, Wheaton, Downers Grove, Lombard,
Bartlett, Carol Stream, Hanover Park, Addison, Glendale Heights, St.
Charles, Woodridge, Glen Ellyn, West Chicago, Batavia, Geneva,
Campton Hills, Oak Brook and Westmont.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4173 8797 4172 8860 4191 8860 4199 8827
      4199 8798
TIME...MOT...LOC 0209Z 263DEG 24KT 4182 8842 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Petr

134 
WWUS53 KLOT 120232
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
932 PM CDT Wed Aug 11 2021

ILC043-089-120245-
/O.CON.KLOT.SV.W.0080.000000T0000Z-210812T0245Z/
Kane IL-DuPage IL-
932 PM CDT Wed Aug 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 945 PM CDT
FOR SOUTHERN KANE AND DUPAGE COUNTIES...

At 930 PM CDT, a severe thunderstorm was located over Batavia, 
moving east at 35 mph. DuPage Airport gusted to 56 mph with this 
storm 930 PM CDT.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Aurora, Naperville, Bolingbrook, Wheaton, Downers Grove, Lombard,
Bartlett, Carol Stream, Hanover Park, Addison, Glendale Heights, St.
Charles, Woodridge, Glen Ellyn, West Chicago, Batavia, Geneva,
Campton Hills, Oak Brook and Westmont.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4177 8860 4194 8849 4199 8827 4199 8798
      4173 8797 4172 8860
TIME...MOT...LOC 0230Z 264DEG 32KT 4183 8830 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Petr

113 
WWUS53 KLOT 120245
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
945 PM CDT Wed Aug 11 2021

ILC043-089-120254-
/O.EXP.KLOT.SV.W.0080.000000T0000Z-210812T0245Z/
Kane IL-DuPage IL-
945 PM CDT Wed Aug 11 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN KANE AND DUPAGE
COUNTIES WILL EXPIRE AT 945 PM CDT...
        
The storm which prompted the warning has moved out Kane county of 
Therefore, the warning will be allowed to expire. A Severe 
Thunderstorm Warning remains in effect for DuPage county until 1030 
PM CDT.

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

LAT...LON 4177 8860 4194 8849 4199 8827 4199 8798
      4173 8797 4172 8860
TIME...MOT...LOC 0244Z 266DEG 33KT 4184 8815 

$$

Petr

The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 11, 9:43 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	26 min
Aug 12, 12:45 AM CDT	Special Weather Statement	LOT	Kendall	45 min
Aug 12, 1:31 AM CDT	Special Weather Statement	LOT	Livingston	44 min
Aug 12, 2:13 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois, Kankakee, Livingston	47 min
Aug 12, 2:22 AM CDT	Special Weather Statement	LOT	Will	38 min
Aug 12, 2:27 AM CDT	Special Weather Statement	LOT	Will	33 min
Aug 12, 2:30 AM CDT	Severe Thunderstorm Warning	LOT	Kankakee, Will	29 min
Aug 12, 2:46 AM CDT	Special Marine Warning	LOT		89 min
Aug 12, 2:50 AM CDT	Special Weather Statement	LOT	LaSalle	40 min
Aug 12, 2:55 AM CDT	Severe Thunderstorm Warning	LOT	Cook	50 min
Aug 12, 3:02 AM CDT	Severe Thunderstorm Warning	LOT	LaSalle	43 min
Aug 12, 3:16 AM CDT	Special Weather Statement	LOT	Grundy, Kendall, Will	44 min
Aug 12, 3:43 AM CDT	Special Weather Statement	LOT	DuPage, Kane, Kendall, Will	47 min
Aug 12, 3:51 AM CDT	Special Weather Statement	LOT	Ford, Iroquois	39 min
Aug 12, 4:59 AM CDT	Special Weather Statement	LOT	Livingston	31 min
Aug 12, 8:01 AM CDT	Special Weather Statement	LOT	Ford	29 min
Aug 12, 8:22 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois	68 min
Aug 12, 9:27 AM CDT	Areal Flood Advisory	LOT	Ford	2 hr
Aug 12, 9:30 AM CDT	Special Weather Statement	LOT	Ford	45 min
Aug 12, 9:59 AM CDT	Flash Flood Warning	LOT	Ford	5 hr
Aug 12, 12:01 PM CDT	Areal Flood Advisory	LOT	Ford	4 hr
Aug 12, 12:09 PM CDT	Special Weather Statement	LOT	Livingston	51 min
Aug 12, 1:09 PM CDT	Special Weather Statement	LOT	Iroquois	51 min
Aug 12, 2:44 PM CDT	Small Craft Advisory	LOT		7 hr
Aug 12, 2:59 PM CDT	Areal Flood Warning	LOT	Ford	19 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 2021 Every severe thunderstorm warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.