EF1 tornado, Detroit to Valley City, Illinois, December 1, 2018

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

December 1, 2018

Touchdown

2:40 PM CST (20:40 UTC)

Lifted

2:42 PM CST (20:42 UTC)

On the ground

2 minutes

Path length

0.6 miles (1.0 km)

Path width

110 yards (101 m)

Deaths

0

Injuries

0

County

Pike County

Touchdown point

39.727, -90.654

Lift-off point

39.719, -90.656

Record number

1812011440-01

25 damage points were recorded along this path by NWS ILX and NWS LSX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 107 mph.

• Trailor was rolled approx 25 yards
• Tornado end. Chaser report

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

By late morning much of the rain shifted north and east of forecast area allowing partial |clearing to destabilize the atmosphere. Steep lapse rates due to relatively cold mid level temperatures southeast of the upper level low combined with strong low-mid level wind shear due to an 80-kt mid level wind max southeast of the upper level low. This led to the development of isolated low topped supercells along the northward moving warm front and ahead of the eastward moving cold front. Eight tornadoes were surveyed over WFO LSX's forecast area.

This short lived tornado began 2 miles northwest of Detroit, IL, along 435th street. Damage was primarily confined to trees, but there was a home with roof damage and a large camper was blown on its side. Overall, the tornado was rated EF0 with a path length of 0.11 miles and a max path width of 25 yards. No injuries or deaths were reported with this tornado.

The tornado began about 1 mile NNW of Valley City, IL. Along County Highway 21, trees were uprooted and a mobile home lost its roof and sustained wall damage. The tornado continued to the northeast, crossing County Highway 21 twice, before lifting. Along this path there was significant tree damage along the east side of Highway 21. Overall, the tornado was rated EF1 with a path length of 0.6 miles and a max path width of 110 yards. No injuries or deaths were reported with this tornado.

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

3 minutes of warning. NWS LSX issued a tornado warning for this county at 20:37 UTC, 3 minutes before the tornado touched down, in force until 21:02 UTC.

The county was under a tornado watch, issued at 20:18 UTC and running to 23:42 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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:58 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 St Louis radar (KLSX), 114 km away, was scanning. The volume nearest the touchdown began at 20:37 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 2018 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

39 more were confirmed in the United States that day.

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.