Alert archive / Illinois / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 91, NWS Chicago, IL
NWS Chicago, IL issued this severe thunderstorm warning at Aug 24, 2021, 7:08 PM CDT for 5 counties in Illinois. It was in force for 67 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 24, 2021, 7:08 PM CDT (00:08 UTC)
- Expired
- Aug 24, 2021, 8:15 PM CDT
- In force
- 67 min
- Issued by
- NWS Chicago, IL
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Cook County, IL, DuPage County, IL, Kane County, IL, Lake County, IL, McHenry County, IL
The radar
The Chicago radar (KLOT), 50 km from the middle of the area, began a volume at 00:12 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 24, 7:17 PM CDT | TSTM WND DMG | Aurora, IL | MULTIPLE REPORTS OF TREES AND WIRES DOWNED IN AURORA. |
| Aug 24, 7:36 PM CDT | TSTM WND DMG | Downers Grove, IL | TWO ROUGHLY 6 INCH DIAMETER TREE LIMBS DOWN ON MAPLE AVENUE. TIME ESTIMATED BASED ON 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 24, 3:55 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
The nearest sounding before it
Lincoln, IL (KILX), launched 00:00Z, 0.1 hours before the alert went out and 216 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.
- Mixed-layer CAPE
- 2737 J/kg
- Mixed-layer CIN
- -9 J/kg
- Mixed-layer LCL
- 1274 m above ground
- 0-6 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 43 m²/s²
- 0-3 km storm-relative helicity
- 120 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 4.3
The text
As transmitted.
192
WUUS53 KLOT 250008
SVRLOT
ILC031-043-089-097-111-250115-
/O.NEW.KLOT.SV.W.0091.210825T0008Z-210825T0115Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Chicago/Romeoville
708 PM CDT Tue Aug 24 2021
The National Weather Service in Chicago has issued a
* Severe Thunderstorm Warning for...
Lake County in northeastern Illinois...
Eastern Kane County in northeastern Illinois...
Eastern McHenry County in northeastern Illinois...
DuPage County in northeastern Illinois...
Cook County in northeastern Illinois...
* Until 815 PM CDT.
* At 707 PM CDT, severe thunderstorms were located along a line
extending from near Powers Lake to Crystal Lake to near South
Elgin to near Montgomery, moving east at 40 mph. This line of
storms has a history of producing wind gusts to 60 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Expect damage to roofs, siding, and trees.
* Locations impacted include...
Chicago, Aurora, Naperville, Elgin, Waukegan, Cicero, Arlington
Heights, Evanston, Schaumburg, Bolingbrook, Palatine, Skokie, Des
Plaines, Oak Lawn, Berwyn, Mount Prospect, Wheaton, Hoffman
Estates, Oak Park and Downers Grove.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4249 8780 4227 8783 4213 8774 4206 8767
4190 8761 4190 8760 4188 8762 4185 8761
4176 8756 4175 8753 4170 8752 4166 8766
4173 8803 4173 8848 4225 8835 4250 8838
TIME...MOT...LOC 0007Z 273DEG 33KT 4258 8830 4225 8835 4202 8836 4177
8838
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...60 MPH
OEMC zones...SEVERE THUNDERSTORM WARNING.
1...2...3...4...5...6...7...8...9...10...11...and 12.
$$
Birk4 follow-up statements
397
WWUS53 KLOT 250027
SVSLOT
Severe Weather Statement
National Weather Service Chicago/Romeoville
727 PM CDT Tue Aug 24 2021
ILC031-043-089-097-111-250115-
/O.CON.KLOT.SV.W.0091.000000T0000Z-210825T0115Z/
Lake IL-Kane IL-McHenry IL-DuPage IL-Cook IL-
727 PM CDT Tue Aug 24 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR LAKE...EASTERN KANE...EASTERN MCHENRY...DUPAGE AND COOK
COUNTIES...
At 726 PM CDT, severe thunderstorms were located along a line
extending from Paddock Lake to Tower Lakes to Roselle to near
Naperville, moving east at 40 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Expect damage to roofs, siding, and trees.
Locations impacted include...
Chicago, Aurora, Naperville, Elgin, Waukegan, Cicero, Arlington
Heights, Evanston, Schaumburg, Bolingbrook, Palatine, Skokie, Des
Plaines, Oak Lawn, Berwyn, Mount Prospect, Wheaton, Hoffman Estates,
Oak Park and Downers Grove.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4249 8780 4227 8783 4213 8774 4206 8767
4190 8761 4190 8760 4188 8762 4185 8761
4176 8756 4175 8753 4170 8752 4166 8766
4173 8803 4173 8843 4224 8830 4250 8824
TIME...MOT...LOC 0026Z 273DEG 35KT 4257 8807 4224 8813 4201 8809 4176
8811
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...60 MPH
OEMC zones...SEVERE THUNDERSTORM WARNING.
1...2...3...4...5...6...7...8...9...10...11...and 12.
$$
Birk206
WWUS53 KLOT 250034
SVSLOT
Severe Weather Statement
National Weather Service Chicago/Romeoville
734 PM CDT Tue Aug 24 2021
ILC089-111-250044-
/O.CAN.KLOT.SV.W.0091.000000T0000Z-210825T0115Z/
Kane IL-McHenry IL-
734 PM CDT Tue Aug 24 2021
...THE SEVERE THUNDERSTORM WARNING FOR EASTERN KANE AND EASTERN
MCHENRY COUNTIES IS CANCELLED...
The storms which prompted the warning have moved out of the warned
area. Therefore, the warning has been cancelled.
A Severe Thunderstorm Watch remains in effect until 1100 PM CDT for
northeastern Illinois.
LAT...LON 4249 8780 4227 8783 4213 8774 4206 8767
4190 8761 4190 8760 4188 8762 4185 8761
4176 8756 4175 8753 4170 8752 4166 8766
4173 8803 4173 8825 4216 8819 4250 8816
TIME...MOT...LOC 0034Z 273DEG 33KT 4257 8798 4224 8804 4201 8800 4176
8802
$$
ILC031-043-097-250115-
/O.CON.KLOT.SV.W.0091.000000T0000Z-210825T0115Z/
Lake IL-DuPage IL-Cook IL-
734 PM CDT Tue Aug 24 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR LAKE...DUPAGE AND COOK COUNTIES...
At 734 PM CDT, severe thunderstorms were located along a line
extending from 6 miles east of Paddock Lake to Hawthorn Woods to Elk
Grove Village to Woodridge, moving east at 40 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Expect damage to roofs, siding, and trees.
Locations impacted include...
Chicago, Aurora, Naperville, Waukegan, Cicero, Arlington Heights,
Evanston, Schaumburg, Bolingbrook, Palatine, Skokie, Des Plaines, Oak
Lawn, Berwyn, Mount Prospect, Wheaton, Hoffman Estates, Oak Park,
Downers Grove and Glenview.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4249 8780 4227 8783 4213 8774 4206 8767
4190 8761 4190 8760 4188 8762 4185 8761
4176 8756 4175 8753 4170 8752 4166 8766
4173 8803 4173 8825 4216 8819 4250 8816
TIME...MOT...LOC 0034Z 273DEG 33KT 4257 8798 4224 8804 4201 8800 4176
8802
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...60 MPH
OEMC zones...SEVERE THUNDERSTORM WARNING.
1...2...3...4...5...6...7...8...9...10...11...and 12.
$$
Birk453
WWUS53 KLOT 250107
SVSLOT
Severe Weather Statement
National Weather Service Chicago/Romeoville
807 PM CDT Tue Aug 24 2021
ILC043-097-250114-
/O.CAN.KLOT.SV.W.0091.000000T0000Z-210825T0115Z/
Lake IL-DuPage IL-
807 PM CDT Tue Aug 24 2021
...THE SEVERE THUNDERSTORM WARNING FOR LAKE AND DUPAGE COUNTIES IS
CANCELLED...
The storms which prompted the warning have moved out of the warned
area. Therefore, the warning has been cancelled.
A Severe Thunderstorm Watch remains in effect until 1100 PM CDT for
northeastern Illinois.
LAT...LON 4206 8767 4190 8761 4190 8760 4188 8762
4185 8761 4176 8756 4175 8753 4170 8752
4166 8766 4170 8790 4172 8789 4188 8779
4203 8779 4213 8774
TIME...MOT...LOC 0104Z 273DEG 33KT 4256 8764 4223 8770 4200 8766 4175
8768
$$
ILC031-250115-
/O.CON.KLOT.SV.W.0091.000000T0000Z-210825T0115Z/
Cook IL-
807 PM CDT Tue Aug 24 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR NORTHEASTERN COOK COUNTY...
At 804 PM CDT, severe thunderstorms were located along a line
extending from 11 miles northeast of Winthrop Harbor to near Highwood
to Edgewater to Auburn Gresham, moving east at 40 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Expect damage to roofs, siding, and trees.
Locations impacted include...
Chicago, Cicero, Evanston, Skokie, Oak Lawn, Berwyn, Oak Park,
Glenview, Niles, West Town, Englewood, Chicago Lawn, Austin, South
Shore, Roseland, West Ridge, Lincoln Park, Bridgeport, Chicago Loop
and South Lawndale.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4206 8767 4190 8761 4190 8760 4188 8762
4185 8761 4176 8756 4175 8753 4170 8752
4166 8766 4170 8790 4172 8789 4188 8779
4203 8779 4213 8774
TIME...MOT...LOC 0104Z 273DEG 33KT 4256 8764 4223 8770 4200 8766 4175
8768
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
OEMC zones...SEVERE THUNDERSTORM WARNING.
1...2...3...4...5...6...7...8...9...10...11...and 12.
$$
Birk833
WWUS53 KLOT 250118
SVSLOT
Severe Weather Statement
National Weather Service Chicago/Romeoville
818 PM CDT Tue Aug 24 2021
ILC031-250127-
/O.EXP.KLOT.SV.W.0091.000000T0000Z-210825T0115Z/
Cook IL-
818 PM CDT Tue Aug 24 2021
...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN COOK COUNTY HAS
EXPIRED...
The storms which prompted the warning have weakened below severe
limits, and have exited the warned area. Therefore, the warning has
been allowed to expire.
A Severe Thunderstorm Watch remains in effect until 1100 PM CDT for
northeastern Illinois.
LAT...LON 4206 8767 4190 8761 4190 8760 4188 8762
4185 8761 4176 8756 4175 8753 4170 8752
4166 8766 4170 8790 4172 8789 4188 8779
4203 8779 4213 8774
TIME...MOT...LOC 0117Z 273DEG 33KT 4255 8747 4222 8753 4199 8749 4174
8751
$$
BirkThe office that day
Everything else NWS Chicago, IL issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 24, 7:04 PM CDT | Special Marine Warning | LOT | 116 min | |
| Aug 24, 7:25 PM CDT | Special Weather Statement | LOT | Grundy, Will | 50 min |
| Aug 24, 7:31 PM CDT | Areal Flood Advisory | LOT | Boone, Lake, McHenry | 3 hr |
| Aug 24, 8:17 PM CDT | Special Weather Statement | LOT | Kankakee, Livingston | 43 min |
| Aug 24, 8:43 PM CDT | Areal Flood Advisory | LOT | Cook | 4 hr |
| Aug 25, 5:42 PM CDT | Severe Thunderstorm Warning | LOT | Cook, DuPage | 33 min |
| Aug 25, 6:23 PM CDT | Areal Flood Advisory | LOT | Cook, DuPage, Will | 3 hr |
| Aug 25, 6:29 PM CDT | Severe Thunderstorm Warning | LOT | Cook, DuPage, Will | 31 min |
| Aug 25, 6:38 PM CDT | Special Marine Warning | LOT | 104 min |
Nearby
Severe Thunderstorm Warnings in Illinois, 2021Every 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.