Alert archive / Illinois / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 85, NWS Chicago, IL
NWS Chicago, IL issued this severe thunderstorm warning at Aug 12, 2021, 3:02 AM CDT for LaSalle County, Illinois. It was in force for 43 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Aug 12, 2021, 3:02 AM CDT (08:02 UTC)
- Expired
- Aug 12, 2021, 3:45 AM CDT
- In force
- 43 min
- Issued by
- NWS Chicago, IL
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
County LaSalle County, IL
The radar
The Chicago radar (KLOT), 74 km from the middle of the area, began a volume at 08:05 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.
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, 8.0 hours before the alert went out and 133 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
- 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
The text
As transmitted.
880
WUUS53 KLOT 120802
SVRLOT
ILC099-120845-
/O.NEW.KLOT.SV.W.0085.210812T0802Z-210812T0845Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Chicago/Romeoville
302 AM CDT Thu Aug 12 2021
The National Weather Service in Chicago has issued a
* Severe Thunderstorm Warning for...
La Salle County in north central Illinois...
* Until 345 AM CDT.
* At 302 AM CDT, severe thunderstorms were located along a line
extending from Peru to Naplate to Seneca, moving north at 30 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Expect damage to roofs, siding, and trees.
* Locations impacted include...
Ottawa, Streator, Peru, La Salle, Mendota, Marseilles, Sheridan,
Lake Holiday, Oglesby, Seneca, Somonauk, Earlville, North Utica,
Serena, Leland, Tonica, Grand Ridge, Naplate, Millington and
Dayton.
Including the following interstates...
I-39 between mile markers 44 and 77.
I-80 between mile markers 74 and 102.
This includes... Buffalo Rock State Park, Illini State Park,
Illinois Valley Community College, Matthiessen State Park, Starved
Rock State Park, and Tri-County Fairgrounds.
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 4163 8917 4163 8860 4114 8859 4114 8888
4115 8916
TIME...MOT...LOC 0802Z 195DEG 28KT 4133 8912 4131 8889 4130 8863
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
Petr3 follow-up statements
022
WWUS53 KLOT 120823
SVSLOT
Severe Weather Statement
National Weather Service Chicago/Romeoville
323 AM CDT Thu Aug 12 2021
ILC099-120845-
/O.CON.KLOT.SV.W.0085.000000T0000Z-210812T0845Z/
La Salle IL-
323 AM CDT Thu Aug 12 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 345 AM CDT
FOR LA SALLE COUNTY...
At 322 AM CDT, severe thunderstorms were located along a line
extending from near La Salle to near Ottawa to near Seneca, moving
northeast at 25 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Expect damage to roofs, siding, and trees.
Locations impacted include...
Ottawa, Peru, La Salle, Mendota, Marseilles, Sheridan, Lake Holiday,
Oglesby, Seneca, Somonauk, Earlville, North Utica, Serena, Leland,
Grand Ridge, Naplate, Millington, Dayton, Ransom and Cedar Point.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4114 8871 4123 8885 4125 8916 4163 8917
4163 8860 4114 8859
TIME...MOT...LOC 0822Z 202DEG 23KT 4138 8908 4139 8882 4136 8860
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
Petr796 WWUS53 KLOT 120833 SVSLOT Severe Weather Statement National Weather Service Chicago/Romeoville 333 AM CDT Thu Aug 12 2021 ILC099-120845- /O.CON.KLOT.SV.W.0085.000000T0000Z-210812T0845Z/ La Salle IL- 333 AM CDT Thu Aug 12 2021 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 345 AM CDT FOR NORTHEASTERN LA SALLE COUNTY... At 333 AM CDT, severe thunderstorms were located along a line extending from 7 miles west of Serena to near Newark, moving northeast at 25 mph. HAZARD...60 mph wind gusts. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. Locations impacted include... Ottawa, Marseilles, Sheridan, Lake Holiday, Seneca, Somonauk, Serena, Leland, Millington, Dayton, Harding, Wedron and Norway. 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 4120 8859 4136 8888 4163 8888 4163 8860 TIME...MOT...LOC 0833Z 206DEG 22KT 4148 8888 4148 8858 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...<.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$ Petr
030
WWUS53 KLOT 120844
SVSLOT
Severe Weather Statement
National Weather Service Chicago/Romeoville
344 AM CDT Thu Aug 12 2021
ILC099-120854-
/O.EXP.KLOT.SV.W.0085.000000T0000Z-210812T0845Z/
La Salle IL-
344 AM CDT Thu Aug 12 2021
...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN LA SALLE COUNTY
WILL EXPIRE AT 345 AM CDT...
The storms which prompted the warning have moved out of the area.
Therefore, the warning will be allowed to expire. However gusty
winds are still possible with these thunderstorms.
A Severe Thunderstorm Watch remains in effect until 400 AM CDT for
north central and northeastern Illinois.
LAT...LON 4120 8859 4136 8888 4163 8888 4163 8860
TIME...MOT...LOC 0844Z 195DEG 28KT 4156 8885 4156 8855
$$
PetrThe office that day
Everything else NWS Chicago, IL issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 11, 8:57 PM CDT | Severe Thunderstorm Warning | LOT | DuPage, Kane | 48 min |
| 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, 3:16 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, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.