Alert archive / Illinois / Severe Thunderstorm Warnings in 2026
Severe Thunderstorm Warning 252, NWS Quad Cities, IA
NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 11, 2026, 8:33 AM CDT for Carroll County, Whiteside County, Illinois. It was in force for 72 min. 1 report 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, 2026, 8:33 AM CDT (13:33 UTC)
- Expired
- Aug 11, 2026, 9:45 AM CDT
- In force
- 72 min
- Issued by
- NWS Quad Cities, IA
- Area
- Storm-based polygon
- Tornado
- Possible
- Damage threat
- Considerable
- Hail
- 0.75 in
- Wind
- 70.0 mph
Counties Carroll County, IL, Whiteside County, IL
The radar
The Quad Cities radar (KDVN), 53 km from the middle of the area, began a volume at 13:36 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, 8:53 AM CDT | TSTM WND DMG | 1 Ssw Morrison, IL | 3-4 inch tree limb snapped. |
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, 7:22 AM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
The nearest sounding before it
Davenport, (KDVN), launched 12:00Z, 1.6 hours before the alert went out and 46 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
- 4268 J/kg
- Mixed-layer CIN
- -76 J/kg
- Mixed-layer LCL
- 891 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 136 m²/s²
- 0-3 km storm-relative helicity
- 153 m²/s²
- Significant tornado parameter
- 2.1
- Supercell composite
- 9.5
The text
As transmitted.
942
WUUS53 KDVN 111333
SVRDVN
ILC015-195-111445-
/O.NEW.KDVN.SV.W.0252.260811T1333Z-260811T1445Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Quad Cities IA/IL
833 AM CDT Tue Aug 11 2026
The National Weather Service in the Quad Cities has issued a
* Severe Thunderstorm Warning for...
Whiteside County in northwestern Illinois...
Southeastern Carroll County in northwestern Illinois...
* Until 945 AM CDT.
* At 832 AM CDT, severe thunderstorms were located along a line
extending from Mississippi Palisades State Park to Andover to
Malone, moving east at 45 mph.
HAZARD...70 mph wind gusts.
SOURCE...Radar indicated. This line of storms has a history of
producing wind damage across portions of eastern Iowa.
IMPACT...Expect considerable tree damage. Damage is likely to
mobile homes, roofs, and outbuildings.
* Locations impacted include...
Sterling, Rock Falls, Morrison, Fulton, Savanna, Prophetstown,
Erie, Garden Plain, Milledgeville, Fairhaven, Tampico, Lyndon,
Sabula, Chadwick, Coleta, Deer Grove, East Clinton, Emerson, Argo
Fay, and Union Grove.
This includes Interstate 88 between mile markers 14 and 44.
This also includes Big Bend Fish and Wildlife Area, Morrison-Rockwood
State Park, and Prophetstown State Park.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.
For your protection move to an interior room on the lowest floor of a
sturdy building.
This is a DANGEROUS SITUATION. These storms are producing widespread
wind damage across portions of eastern Iowa. SEEK SHELTER NOW inside
a sturdy structure and stay away from windows!
&&
LAT...LON 4159 8963 4159 9016 4163 9016 4164 9017
4165 9016 4166 9018 4178 9020 4190 9015
4196 9016 4200 9014 4206 9017 4210 9016
4203 8969 4193 8969 4193 8963
TIME...MOT...LOC 1332Z 288DEG 40KT 4213 9020 4197 9025 4183 9047
TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH
$$
Uttech3 follow-up statements
981
WWUS53 KDVN 111401 RRA
SVSDVN
Severe Weather Statement
National Weather Service Quad Cities IA/IL
901 AM CDT Tue Aug 11 2026
ILC015-195-111445-
/O.CON.KDVN.SV.W.0252.000000T0000Z-260811T1445Z/
Whiteside IL-Carroll IL-
901 AM CDT Tue Aug 11 2026
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 945 AM CDT
FOR WHITESIDE AND SOUTHEASTERN CARROLL COUNTIES...
At 901 AM CDT, severe thunderstorms were located along a line
extending from near Chadwick to White Pigeon to Spring Hill, moving
east at 45 mph.
HAZARD...70 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Expect considerable tree damage. Damage is likely to mobile
homes, roofs, and outbuildings.
Locations impacted include...
Sterling, Rock Falls, Morrison, Fulton, Prophetstown, Erie, Garden
Plain, Milledgeville, Fairhaven, Tampico, Lyndon, Chadwick, Coleta,
Deer Grove, Emerson, Argo Fay, East Clinton, Union Grove, Ustick, and
Fenton.
This also includes Big Bend Fish and Wildlife Area, Morrison-Rockwood
State Park, and Prophetstown State Park.
This includes Interstate 88 between mile markers 13 and 44.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.
For your protection move to an interior room on the lowest floor of a
sturdy building.
Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4159 8963 4159 9016 4163 9016 4164 9017
4165 9016 4166 9018 4178 9020 4189 9013
4196 9009 4207 8999 4203 8969 4193 8969
4193 8963
TIME...MOT...LOC 1401Z 287DEG 40KT 4204 8982 4188 8987 4161 9003
TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH
$$
Uttech325
WWUS53 KDVN 111421
SVSDVN
Severe Weather Statement
National Weather Service Quad Cities IA/IL
921 AM CDT Tue Aug 11 2026
ILC015-111431-
/O.CAN.KDVN.SV.W.0252.000000T0000Z-260811T1445Z/
Carroll IL-
921 AM CDT Tue Aug 11 2026
...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN CARROLL COUNTY 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 200 PM CDT for
northwestern Illinois.
&&
LAT...LON 4159 9001 4193 8975 4193 8963 4159 8963
TIME...MOT...LOC 1421Z 293DEG 44KT 4197 8954 4163 8959 4154 8976
$$
ILC195-111445-
/O.CON.KDVN.SV.W.0252.000000T0000Z-260811T1445Z/
Whiteside IL-
921 AM CDT Tue Aug 11 2026
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 945 AM CDT
FOR EASTERN WHITESIDE COUNTY...
At 921 AM CDT, severe thunderstorms were located along a line
extending from near Polo to near Deer Grove to near New Bedford,
moving southeast at 50 mph.
HAZARD...70 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Expect considerable tree damage. Damage is likely to mobile
homes, roofs, and outbuildings.
Locations impacted include...
Sterling, Rock Falls, Prophetstown, Tampico, Deer Grove, Emerson,
Yeoward Addition, Whiteside County Airport, Galt, Prophetstown State
Recreation Area, Penrose, Como, Leon Corners, Grimes Addition,
Douglas Park, and Agnew.
This also includes Prophetstown State Park.
This includes Interstate 88 between mile markers 30 and 44.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A tornado watch remains in effect for the warned area. Tornadoes can
develop quickly from severe thunderstorms. Although a tornado is not
immediately likely, if one is spotted act quickly and move to a place
of safety inside a sturdy structure, such as a basement or small
interior room.
For your protection move to an interior room on the lowest floor of a
sturdy building.
Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4159 9001 4193 8975 4193 8963 4159 8963
TIME...MOT...LOC 1421Z 293DEG 44KT 4197 8954 4163 8959 4154 8976
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH
$$
Uttech267 WWUS53 KDVN 111438 SVSDVN Severe Weather Statement National Weather Service Quad Cities IA/IL 938 AM CDT Tue Aug 11 2026 ILC195-111448- /O.EXP.KDVN.SV.W.0252.000000T0000Z-260811T1445Z/ Whiteside IL- 938 AM CDT Tue Aug 11 2026 ...THE SEVERE THUNDERSTORM WARNING FOR EASTERN WHITESIDE COUNTY WILL EXPIRE AT 945 AM CDT... The storms which prompted the warning have moved out of the area. Therefore, the warning will be allowed to expire. Gusty winds are still possible. A Severe Thunderstorm Watch remains in effect until 200 PM CDT for northwestern Illinois. && LAT...LON 4159 9001 4193 8975 4193 8963 4159 8963 TIME...MOT...LOC 1438Z 288DEG 40KT 4197 8954 4163 8959 4154 8976 $$ Uttech
The office that day
Everything else NWS Quad Cities, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 11, 8:15 AM CDT | Severe Thunderstorm Warning | DVN | Carroll, Jo Daviess, Stephenson | 60 min |
| Aug 11, 8:20 AM CDT | Severe Thunderstorm Warning | DVN | Rock Island, Whiteside | 43 min |
| Aug 11, 8:38 AM CDT | Tornado Warning | DVN | Rock Island, Whiteside | 23 min |
| Aug 11, 8:43 AM CDT | Severe Thunderstorm Warning | DVN | Jo Daviess, Stephenson | 51 min |
| Aug 11, 8:54 AM CDT | Severe Thunderstorm Warning | DVN | Bureau, Henry, Rock Island | 81 min |
| Aug 11, 9:34 AM CDT | Severe Thunderstorm Warning | DVN | Bureau, Putnam | 42 min |
Nearby
Severe Thunderstorm Warnings in Illinois, 2026Every severe thunderstorm warning in 2026
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.