Tornadoes · United States · Illinois · 2023
EF0 tornado, Oswego to Boulder Hill, Illinois, July 12, 2023
From Oswego to Boulder Hill, this EF0 tornado ran 4.1 miles across Kendall County on July 12, 2023, touching down at 5:36 PM CDT and reaching 100 yards wide. It killed nobody.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
EF2111 to 135 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
EF3136 to 165 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
EF5over 200 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unrated
The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.
The record
- Rating
- EF0
- Date
- July 12, 2023
- Touchdown
- 5:36 PM CDT (22:36 UTC)
- Lifted
- 5:44 PM CDT (22:44 UTC)
- On the ground
- 8 minutes
- Path length
- 4.1 miles (6.7 km)
- Path width
- 100 yards (91 m)
- Deaths
- 0
- Injuries
- 0
- County
- Kendall County
- Touchdown point
- 41.693, -88.333
- Lift-off point
- 41.722, -88.264
- Record number
- 2307121636-01
The damage survey
17 damage points were recorded along this path by NWS LOT, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 85 mph.
- Large tree limbs snapped off and/or trees uprooted. Some signs of rot in damaged trees.
- Also sporadic portions of fences down in addition to the fruit tree damage. Trampoline damaged.
- Fascia damage, with the portion of fascia lofted into a nearby yard. Also included similar Bradford Pear tree damage to other damage nearby.
- Small diameter tree trunk peeled back
Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.
What the Weather Service recorded
During the evening of July 12, scattered thunderstorms dropped 13 tornadoes across far northeast Illinois, primarily within the west of northwest suburbs of Chicago. Of these 13 tornadoes, three were determined to be EF-1 with the remaining 10 being EF-0.
An EF-0 tornado impacted northeastern Oswego and southeastern Aurora. Damage along the tornado's path was characterized primarily by downed trees and tree limbs, as well as a few instances of exterior damage to homes.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.
The county was under a tornado watch, issued at 20:53 UTC and running to 23:51 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 09:24 UTC | 12:30 UTC | Flood Advisory | LOT |
| 20:53 UTC | 23:51 UTC | Tornado Watch | LOT |
| 22:37 UTC | 22:48 UTC | Tornado Warning | LOT |
Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.
The forecast that day
The Storm Prediction Center had this point in a Enhanced Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 20:00 UTC.
SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.
The air that afternoon
The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.
Lincoln, IL (KILX), 12:00Z
10.6 hours before the tornado, 175 km from the path. July 12, 2023.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- -87861 J/kg
- Surface CAPE
- 0 J/kg
- Mixed-layer LCL
- 2084 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km bulk shear
- 17 kt
- 0-1 km storm-relative helicity
- 81 m²/s²
- 0-3 km storm-relative helicity
- 80 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 5.1 K/km
Lincoln, IL (KILX), 00:00Z
1.4 hours after it, 175 km from the path. July 13, 2023.
- Mixed-layer CAPE
- 898 J/kg
- Mixed-layer CIN
- -76 J/kg
- Surface CAPE
- 1547 J/kg
- Mixed-layer LCL
- 1238 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 133 m²/s²
- 0-3 km storm-relative helicity
- 299 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 7.0
- 0-3 km lapse rate
- 6.1 K/km
The surface observations
Chicago/Aurora (ARR), 17 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 20:40 UTC | 140° 9 kt | 1007.5 | ||||
| 20:45 UTC | 150° 9 kt | 1007.5 | ||||
| 20:50 UTC | 150° 8 kt | 1007.5 | ||||
| 20:52 UTC | 72 | 69 | 160° 7 kt | 1007.5 | ||
| 20:55 UTC | 150° 7 kt | 1007.5 | ||||
| 21:00 UTC | 140° 8 kt | 1007.1 | ||||
| 21:05 UTC | 140° 8 kt | 1007.1 | ||||
| 21:10 UTC | 150° 7 kt | 1007.1 | ||||
| 21:15 UTC | 160° 7 kt | 1007.1 | ||||
| 21:20 UTC | 150° 7 kt | 1007.1 | ||||
| 21:25 UTC | 150° 5 kt | 1006.8 | ||||
| 21:30 UTC | 160° 5 kt | 1006.8 | ||||
| 21:35 UTC | 160° 7 kt | 1006.8 | ||||
| 21:40 UTC | 160° 5 kt | 1006.4 | ||||
| 21:45 UTC | 160° 10 kt | 1006.4 | ||||
| 21:50 UTC | 160° 8 kt | 1006.1 | ||||
| 21:52 UTC | 74 | 71 | 160° 9 kt | 1006.1 | ||
| 21:55 UTC | 170° 9 kt | 1006.4 | ||||
| 22:00 UTC | 170° 7 kt | 1006.1 | ||||
| 22:05 UTC | 170° 4 kt | 1005.8 | ||||
| 22:10 UTC | 240° 4 kt | 1005.8 | ||||
| 22:15 UTC | 230° 4 kt | 1005.8 | ||||
| 22:20 UTC | 190° 4 kt | 1005.8 | ||||
| 22:25 UTC | 170° 5 kt | 1005.8 | ||||
| 22:30 UTC | 180° 7 kt | 1005.8 | ||||
| 22:35 UTC | 160° 7 kt | 1005.4 | ||||
| 22:40 UTC | 170° 4 kt | 1005.4 | ||||
| 22:45 UTC | 180° 5 kt | 1005.4 | ||||
| 22:50 UTC | 190° 5 kt | 1005.4 | ||||
| 22:52 UTC | 78 | 73 | 190° 6 kt | 1005.4 | ||
| 22:55 UTC | 200° 5 kt | 1005.4 | ||||
| 23:00 UTC | 210° 8 kt | 1005.4 | ||||
| 23:05 UTC | 210° 9 kt | 1005.4 | ||||
| 23:10 UTC | 200° 8 kt | 1005.1 | ||||
| 23:15 UTC | 1005.1 | |||||
| 23:20 UTC | 19 | 1005.1 | ||||
| 23:25 UTC | 17 | 1005.1 | ||||
| 23:30 UTC | 1005.4 | |||||
| 23:35 UTC | 1005.4 | -RA | ||||
| 23:40 UTC | 250° 11 kt | 1005.4 | -RA | |||
| 23:45 UTC | 21 | 1005.8 | -RA | |||
| 23:50 UTC | 16 kt | 22 | 1006.1 | -RA | ||
| 23:52 UTC | 73 | 68 | 300° 17 kt | 26 | 1006.4 | |
| 23:55 UTC | 16 kt | 22 | 1006.4 | |||
| 23:59 UTC | 73 | 67 | 290° 15 kt | 25 | 1006.4 | |
| 00:00 UTC | 290° 16 kt | 21 | 1006.4 | |||
| 00:05 UTC | 23 | 1006.8 | ||||
| 00:10 UTC | 27 | 1006.8 | ||||
| 00:15 UTC | 23 | 1006.8 | ||||
| 00:20 UTC | 22 | 1006.8 | ||||
| 00:25 UTC | 280° 16 kt | 1006.8 | ||||
| 00:30 UTC | 21 | 1007.1 | ||||
| 00:35 UTC | 18 | 1007.1 |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Chicago radar (KLOT), 21 km away, was scanning. The volume nearest the touchdown began at 22:34 UTC.
Open the radar archive at this moment, over the track
Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.
What was reported nearby
Local storm reports within 60 km of the path, in the three hours either side.
| Time (UTC) | Report | Where | County | Remark |
|---|---|---|---|---|
| 19:38 UTC | RAIN 1.69 | 3 Ssw Burr Ridge | Dupage, IL | Mesonet station GW3333 Burr Ridge, 3hr total. |
| 20:26 UTC | RAIN 4.56 | 1 Nnw Oswego | Kendall, IL | Spotter measured 4.56in of rain in 24hrs. |
| 22:27 UTC | TSTM WND DMG | 1 Ne Oswego | Kendall, IL | Six inch tree limb down at Fox Bend Golf Course. Possible Tornado. Time Estimated. |
| 22:34 UTC | FUNNEL CLOUD | 1 Sse Boulder Hill | Kendall, IL | Funnel Cloud observed from the NWS Chicago office in Romeoville. |
| 22:36 UTC | TORNADO | 1 S Boulder Hill | Kendall, IL | An NWS damage survey determined an EF-0 tornado with estimated peak winds of 85 mph, path width of 100 yards, and path length of 2.8 miles impacted Oswego and Aurora. Damage along the path of the tornado consisted of sna |
| 23:06 UTC | TORNADO | 4 N Hampshire | Mchenry, IL | An NWS damage survey determined an EF-1 tornado with estimated peak winds of 90 mph, path width of 200 yards, and path length of 6.9 miles impacted Huntley. Damage along the path of the tornado consisted of snapped tree |
| 23:09 UTC | TORNADO | 1 Wsw Burr Ridge | Dupage, IL | *** 1 INJ *** An NWS damage survey determined an EF-1 tornado with estimated peak winds of 110 mph, path width of 150 yards, and path length of 9.2 miles started near Burr Ridge and ended in Stickney. Damage along the pa |
| 23:15 UTC | TORNADO | Huntley | Mchenry, IL | One roof blown off in Huntley. Time estimated. |
| 23:16 UTC | TORNADO | 2 Ene Huntley | Mchenry, IL | Trees down and damage reported to homes near Algonquin and Reed Roads. Time Estimated. |
| 23:16 UTC | TORNADO | 4 Ssw Pingree Grove | Kane, IL | An NWS damage survey determined an EF-1 tornado with estimated peak winds of 100 mph, path width of 440 yards, and path length of 11.0 miles impacted Plato Center and Elgin. Damage along the path of the tornado consisted |
| 23:16 UTC | TORNADO | Countryside | Cook, IL | Trees uprooted and roofs blown off near Joliet Road and LaGrange Road. Time Estimated. |
| 23:17 UTC | TORNADO | 1 E La Grange | Cook, IL | Car windows reported blown out and damage to signs near East Ave. Time estimated. |
| 23:18 UTC | TORNADO | 4 N Campton Hills | Kane, IL | An NWS Damage Survey determined an EF-0 tornado with max estimated winds of 85 mph, path width of 100 yards, and path length of 2.6 miles impacted Campton Hills to Elgin. Damage along the path of the tornado was almost e |
| 23:20 UTC | TORNADO | Mccook | Cook, IL | Photo shared on social media of a structure damaged. Time estimated. |
| 23:23 UTC | TORNADO | 3 Nw South Elgin | Kane, IL | Large trees 20 inches in diameter down and damage reported to homes, west of Elgin, northeast of Campton Hills. Location and time estimated. |
| 23:23 UTC | TORNADO | Forest View | Cook, IL | Video of roof peeled back off building. Debris swirling in air near 47th and Harlem. Time estimated by radar. |
| 23:33 UTC | TORNADO | 2 Sse Fox River Grove | Mchenry, IL | An NWS damage survey determined an EF-0 tornado with estimated peak winds of 80 mph, path width of 125 yards, and path length of 3.4 miles impacted Barrington Hills and Barrington. Damage along the path of the tornado co |
| 23:41 UTC | TORNADO | 1 Nnw Hanover Park | Cook, IL | An NWS damage survey determined a brief EF-0 tornado with estimated peak winds of 80 mph, path width of 80 yards, and path length of one half of a mile impacted Streamwood. The tornado stripped siding off two walls at a |
| 23:43 UTC | TORNADO | 1 Nnw Carol Stream | Dupage, IL | An NWS damage survey determined an EF-0 tornado with estimated peak winds of 85 mph, path width of 125 yards, and path length of 2.9 miles impacted Carol Stream and Glendale Heights. The tornado produced primarily tree d |
| 23:43 UTC | TORNADO | 2 Ne Hanover Park | Cook, IL | An NWS damage survey determined a brief EF-0 tornado with estimated peak winds of 70 mph, path width of 80 yards, and path length of 1.1 miles impacted Schaumburg. Tree damage was common along the path of the tornado. |
| 23:44 UTC | TORNADO | 1 N Carol Stream | Dupage, IL | Trees snapped and debris lofted. Time estimated. |
| 23:44 UTC | TORNADO | 1 Nne Carol Stream | Dupage, IL | Report of numerous trees down between Kuhn Rd at Deerskin Trail and Gary Ave at Elk Trail in Carol Stream. One trunk between 14 and 16 inches in diameter had snapped. Heaviest damage noted at Western Trails School. Time |
| 23:52 UTC | TORNADO | 1 Nw Long Grove | Lake, IL | An NWS damage survey determined an EF-0 tornado with estimated peak winds of 70 mph, path width of 125 yards, and path length of 2.1 miles impacted Long Grove. The tornado produced primarily tree damage including at the |
| 23:54 UTC | TORNADO | 1 Nne Itasca | Dupage, IL | An NWS damage survey determined an EF-0 tornado with estimated peak winds of 85 mph, path width of 225 yards, and path length of 3.5 miles started near Itasca and lifted over Chicago OHare Airport. Damage along the path |
| 23:59 UTC | TORNADO | 2 Wnw Ohare Airport | Cook, IL | Warehouses reported damaged on the west side of Ohare Airport. Location and time estimated. |
| 00:02 UTC | TORNADO | 2 N Ohare Airport | Cook, IL | An NWS damage survey determined an EF-0 tornado with estimated peak winds of 85 mph, path width of 300 yards, and path length of 3.5 miles started near Chicago OHare Airport and continued into Park Ridge. This tornado st |
| 00:02 UTC | TORNADO | 2 N Ohare Airport | Cook, IL | Corrects previous tornado report from 2 N Ohare Airport. An NWS damage survey determined an EF-0 tornado with estimated peak winds of 85 mph, path width of 300 yards, and path length of 3.5 miles started near Chicago OHa |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2023 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are
The other tornadoes of July 12, 2023
23 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| July 12 | 3:43 AM CDT | EF1 | Lafayette, AR | 2.8 | 350 | $15,000 | ||
| July 12 | 5:14 AM CDT | EF1 | Colfax, NE | 0.3 | 50 | |||
| July 12 | 5:20 AM CDT | EF1 | Cuming, NE | 0.5 | 90 | |||
| July 12 | 5:37 AM CDT | EF0 | Burt, NE | 1.1 | 15 | |||
| July 12 | 6:05 AM CDT | EF2 | Harrison, IA | 9.4 | 100 | |||
| July 12 | 6:17 AM CDT | EF1 | Shelby, IA | 0.5 | 50 | |||
| July 12 | 6:28 AM CDT | EF1 | Pottawattamie, IA | 1.5 | 40 | |||
| July 12 | 6:32 AM CDT | EF0 | Pottawattamie, IA | 0.9 | 40 | |||
| July 12 | 6:38 AM CDT | EF0 | Cass, IA | 1.5 | 50 | |||
| July 12 | 6:39 AM CDT | EF0 | Cass, IA | 2.1 | 75 | $5,000 | ||
| July 12 | 5:25 PM CDT | EF0 | Boone, IL | 2.5 | 175 | |||
| July 12 | 6:06 PM CDT | EF1 | McHenry, IL | 6.4 | 200 | |||
| July 12 | 6:09 PM CDT | EF1 | DuPage, IL | 9.1 | 150 | 1 | ||
| July 12 | 6:16 PM CDT | EF1 | Kane, IL | 10.9 | 440 | |||
| July 12 | 6:18 PM CDT | EF0 | Kane, IL | 2.6 | 100 | |||
| July 12 | 6:33 PM CDT | EF0 | McHenry, IL | 3.4 | 125 | |||
| July 12 | 6:41 PM CDT | EF0 | Cook, IL | 0.5 | 80 | |||
| July 12 | 6:43 PM CDT | EF0 | Cook, IL | 1.1 | 80 | |||
| July 12 | 6:44 PM CDT | EF0 | DuPage, IL | 2.9 | 125 | |||
| July 12 | 6:52 PM CDT | EF0 | Lake, IL | 2.1 | 125 | |||
| July 12 | 6:54 PM CDT | EF0 | DuPage, IL | 3.4 | 225 | |||
| July 12 | 7:02 PM CDT | EF0 | Cook, IL | 3.4 | 300 | |||
| July 12 | 11:09 PM EDT | EF1 | Saint Joseph, MI | 2.9 | 50 | $50,000 |
What this means
Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.