Alert archive / Illinois / Tornado Warnings in 2021

Tornado Warning 5, NWS Chicago, IL

June 20, 2021Cook County, DuPage County, Illinois

NWS Chicago, IL issued this tornado warning at Jun 20, 2021, 11:15 PM CDT for Cook County, DuPage County, Illinois. It was in force for 30 min. 3 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: Jun 20, 2021, 11:15 PM CDT (04:15 UTC)
Expired: Jun 20, 2021, 11:45 PM CDT
In force: 30 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Cook County, IL, DuPage County, IL

The radar

The Chicago radar (KLOT), 28 km from the middle of the area, began a volume at 04:17 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
Jun 20, 11:15 PM CDT	TSTM WND DMG	Downers Grove, IL	SEVERAL TREES DOWNED IN DOWNERS GROVE. TIME ESTIMATED BY RADAR.
Jun 20, 11:18 PM CDT	TSTM WND DMG	Westmont, IL	SEVERAL TREES DOWNED IN WESTMONT. TIME ESTIMATED BY RADAR.
Jun 20, 11:40 PM CDT	TSTM WND DMG	1 Wnw Gage Park - Chica, IL	NUMEROUS TREE BRANCHES DOWNED. TREE BRANCH BROKE A WINDOW. SOME TREES SNAPPED NEAR THE TOP. 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
Jun 20, 9:40 PM CDT	Severe Thunderstorm Watch	SPC	4 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 4.3 hours before the alert went out and 195 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: 1632 J/kg
Mixed-layer CIN: -62 J/kg
Mixed-layer LCL: 1351 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 159 m²/s²
0-3 km storm-relative helicity: 421 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 13.7

Open this sounding in Storm Lab

The text

As transmitted.

520 
WFUS53 KLOT 210415
TORLOT
ILC031-043-210500-
/O.NEW.KLOT.TO.W.0005.210621T0415Z-210621T0500Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Chicago/Romeoville
1115 PM CDT Sun Jun 20 2021

The National Weather Service in Chicago has issued a

* Tornado Warning for...
  East central DuPage County in northeastern Illinois...
  Central Cook County in northeastern Illinois...

* Until midnight CDT.
    
* At 1114 PM CDT, a severe thunderstorm capable of producing a
  tornado was located over Westmont, or over Downers Grove, moving
  east at 45 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 dangerous storm will be near...
  Westchester, La Grange Park, Western Springs and Hillside around 
  1120 PM CDT.
  Maywood, Brookfield, La Grange, Summit, Bellwood, Forest Park, 
  River Forest, Lyons, Riverside and Broadview around 1125 PM CDT.
  Cicero, Berwyn, Oak Park, Austin and Stickney around 1130 PM CDT.

Other locations in the path of this tornadic thunderstorm include
South Lawndale, West Town, Brighton Park, Humboldt Park, East
Garfield Park and Near West Side.

This includes...  Brookfield Zoo, Hawthorne Park, and Morton
Arboretum.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4178 8807 4186 8807 4190 8769 4179 8769
TIME...MOT...LOC 0414Z 268DEG 41KT 4181 8799 

TORNADO...RADAR INDICATED
HAIL...<.75IN

OEMC zones...TORNADO WARNING.  
3...6...and 8.
 
$$

FRIEDLEIN

3 follow-up statements

430 
WWUS53 KLOT 210426
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
1126 PM CDT Sun Jun 20 2021

ILC031-043-210500-
/O.CON.KLOT.TO.W.0005.000000T0000Z-210621T0500Z/
DuPage IL-Cook IL-
1126 PM CDT Sun Jun 20 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL MIDNIGHT CDT FOR EAST
CENTRAL DUPAGE AND CENTRAL COOK COUNTIES...
    
At 1125 PM CDT, a severe thunderstorm capable of producing a tornado 
was located over La Grange, moving east at 35 mph. The original 
rotation near Downers Grove has weakened slightly as this storm has 
moved into western Cook County, however still some rotation is 
present. The strongest rotation is just south of Countryside where 
another Tornado Warning is present.

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 dangerous storm will be near...
  Summit around 1130 PM CDT.
  Cicero, Berwyn and Stickney around 1135 PM CDT.

Other locations in the path of this tornadic thunderstorm include
South Lawndale, Brighton Park, East Garfield Park and Near West Side.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4178 8799 4187 8796 4190 8769 4179 8769
TIME...MOT...LOC 0425Z 275DEG 29KT 4180 8787 

TORNADO...RADAR INDICATED
HAIL...<.75IN

OEMC zones...TORNADO WARNING.  
3...6...and 8.
 
$$

FRIEDLEIN

808 
WWUS53 KLOT 210435
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
1135 PM CDT Sun Jun 20 2021

ILC043-210444-
/O.CAN.KLOT.TO.W.0005.000000T0000Z-210621T0500Z/
DuPage IL-
1135 PM CDT Sun Jun 20 2021

...THE TORNADO WARNING FOR EAST CENTRAL DUPAGE COUNTY 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 AM CDT for
northeastern Illinois.

LAT...LON 4178 8789 4187 8778 4189 8769 4179 8769
TIME...MOT...LOC 0434Z 268DEG 41KT 4180 8773 

$$

ILC031-210500-
/O.CON.KLOT.TO.W.0005.000000T0000Z-210621T0500Z/
Cook IL-
1135 PM CDT Sun Jun 20 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL MIDNIGHT CDT FOR EAST
CENTRAL COOK COUNTY...
    
At 1134 PM CDT, a severe thunderstorm capable of producing a tornado 
near Burbank, moving east at 45 mph. The rotation in this storm has 
shown weakening over the past 10 minutes, and if this trend 
continues, a downstream warning will not be needed and this warning 
will be allowed to expire.

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
east central Cook County, including the following locations... Archer
Heights, Gage Park, Forest View, McCook, North Lawndale, West
Garfield Park, Garfield Ridge and West Elsdon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4178 8789 4187 8778 4189 8769 4179 8769
TIME...MOT...LOC 0434Z 268DEG 41KT 4180 8773 

TORNADO...RADAR INDICATED
HAIL...<.75IN

OEMC zones...TORNADO WARNING. 6 and 8.
 
$$

FRIEDLEIN

333 
WWUS53 KLOT 210445
SVSLOT

Severe Weather Statement
National Weather Service Chicago/Romeoville
1145 PM CDT Sun Jun 20 2021

ILC031-210454-
/O.CAN.KLOT.TO.W.0005.000000T0000Z-210621T0500Z/
Cook IL-
1145 PM CDT Sun Jun 20 2021

...THE TORNADO WARNING FOR EAST CENTRAL COOK COUNTY IS CANCELLED...
        
The storm which prompted the warning has weakened in rotation, and 
has exited the warned area. Therefore, the warning has been 
cancelled. However gusty winds are still possible with these 
thunderstorms.

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

LAT...LON 4178 8789 4187 8778 4189 8769 4179 8769
TIME...MOT...LOC 0443Z 268DEG 41KT 4180 8757 

$$

FRIEDLEIN

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 20, 8:39 PM CDT	Severe Thunderstorm Warning	LOT	Winnebago	21 min
Jun 20, 9:02 PM CDT	Severe Thunderstorm Warning	LOT	Ogle	58 min
Jun 20, 10:12 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb	33 min
Jun 20, 10:22 PM CDT	Severe Thunderstorm Warning	LOT	Kane	53 min
Jun 20, 10:40 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	50 min
Jun 20, 10:43 PM CDT	Tornado Warning	LOT	DuPage, Kane	32 min
Jun 20, 10:46 PM CDT	Tornado Warning	LOT	Cook, DuPage	20 min
Jun 20, 10:48 PM CDT	Special Marine Warning	LOT		117 min
Jun 20, 10:50 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Grundy, Kane, Kendall, LaSalle	55 min
Jun 20, 10:56 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Will	79 min
Jun 20, 11:05 PM CDT	Tornado Warning	LOT	Cook, DuPage, Will	40 min
Jun 20, 11:08 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kane, Kendall, Lake, McHenry and 1 more	4 hr
Jun 20, 11:30 PM CDT	Severe Thunderstorm Warning	LOT	Cook	30 min
Jun 20, 11:41 PM CDT	Severe Thunderstorm Warning	LOT	Kankakee, Will	79 min
Jun 21, 12:00 AM CDT	Tornado Warning	LOT	Will	34 min
Jun 21, 3:22 PM CDT	Small Craft Advisory	LOT		7 hr

Nearby

Tornado Warnings in Illinois, 2021 Every tornado warning in 2021 Tornadoes 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.