EF1 tornado, Mt Carroll to Shannon, Illinois, March 31, 2023

1. EF065 to 85 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mphthis tornado

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. 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.

4. 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.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. 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.

7. 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.

Rating

EF1

Date

March 31, 2023

Touchdown

6:39 PM CDT (23:39 UTC)

Lifted

6:42 PM CDT (23:42 UTC)

On the ground

3 minutes

Path length

1.0 miles (1.6 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Carroll County

Touchdown point

42.049, -89.973

Lift-off point

42.058, -89.959

Record number

2303311739-01

6 damage points were recorded along this path by NWS DVN and NWS LOT, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 110 mph.

• Posts to Illinois Storm Chasers facebook page mention "trampoline and kayaks gone" and show show collapsed playground furniture in backyard. Near Coleta.
• Damage to four pine trees, two were snapped.
• Extensive damage to outbuildings at two farms.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

A very strong system developed on the morning of March 31st and tracked across the state of Iowa. This system pulled unseasonably warm and moist air into the Midwest, which combined with a very favorable wind profile to create a volatile environment for severe thunderstorms. Discrete supercell thunderstorms occurred initially, but quickly transitioned into a QLCS mode. This system produced a historic tornado outbreak for the area, with a record 29 tornadoes on the day, including 13 rated EF-2, 1 rated EF-3, and 1 rated EF-4. This was the first EF-4 tornado in the NWS Quad Cities service area since 1995. 11 injuries were reported, with no known fatalities. In addition to the numerous tornadoes, there were many large hail and damaging wind reports. Maximum straight line thunderstorm winds were estimated at 80 to 90 mph.

A brief tornado occurred near Mt. Carroll as a line of supercell thunderstorms swept northeast over Illinois on March 31st. This tornado was found using satellite information to identify a damage track. There was confirmed powerline damage in that track.

This tornado began southeast of Lanark in Carroll County and tracked to the northeast before moving into Ogle County about a quarter mile north of the intersection of W White Oak Road and N Brookville Road. The tornado path then continued for about 5 miles through Ogle County (see NWS Chicago StormData). The tornado then crossed into Stephenson County, just east of the intersection of N Mt. Vernon Road and Montague Road. This tornado caused extensive damage to several farm buildings and also downed a few trees along its path. The tornado was rated EF-1 in Carroll and Ogle Counties. In Stephenson County, there was no observable damage so the rating is |EF-U.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

27 minutes of warning. NWS DVN issued a tornado warning for this county at 23:12 UTC, 27 minutes before the tornado touched down, in force until 23:44 UTC.

The county was under a tornado watch, issued at 16:47 UTC and running to 01:00 UTC.

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 Storm Prediction Center had this point in a Moderate Risk, with a 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:54 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 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.

The Quad Cities radar (KDVN), 71 km away, was scanning. The volume nearest the touchdown began at 23:42 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.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2023 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

126 more were confirmed in the United States that day.

All 127 of them

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.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.