EF1 tornado, St Jacob to Highland, Illinois, March 27, 2021

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 27, 2021

Touchdown

7:08 PM CDT (00:08 UTC)

Lifted

7:15 PM CDT (00:15 UTC)

On the ground

7 minutes

Path length

5.3 miles (8.5 km)

Path width

700 yards (640 m)

Deaths

0

Injuries

0

County

Madison County

Touchdown point

38.732, -89.770

Lift-off point

38.735, -89.672

Record number

2103271808-01

34 damage points were recorded along this path by NWS LSX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 93 mph.

• Only one pole snapped, surrounding area and damage doesn’t warrant 98mph
• Eye witness account of straight line wind damage
• Metal siding is found in trees and cross the road
• Big limbs but tree is rotted

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

A cold front swept through the region on March 27th. The low level forcing along the front, increasing upper level ascent downstream of an approaching shortwave, and at least modest moisture and instability were sufficient to generate thunderstorms as the front moved through the region. There were numerous reports of large hail and damaging winds as well as one tornado.

Intermittent, low end tornado damage was found on a path from just north of Saint Jacob, IL eastward into the Highland, IL area. The tornado first touched down north of Saint Jacob, IL along Marine Road where it toppled several trees and partially tore the roof off a large metal shed. The tornado then likely lifted briefly, but then touched down again intermittently along Lake Road. The tornado did minor roof and siding damage to many homes along Lake Road, as well as topple several trees and snapped a power line. The worst of the damage, which was rated EF-1, was to a large metal shed that was destroyed and the roof was lofted into nearby trees and pushed hundreds of feet down the street. In addition, a 2x4 from this roof was driven straight into the roof of a nearby building. The tornado then likely lifted briefly, before touching down again and doing additional damage to large trees in a neighborhood along 15th and 16th Streets. The tornado then lifted and dissipated. Overall the tornado was rated EF1 with a path length of 5.29 miles and a max path width of 700 yards. No injuries or deaths were reported.

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

5 minutes of warning. NWS LSX issued a tornado warning for this county at 00:03 UTC, 5 minutes before the tornado touched down, in force until 00:45 UTC.

The county was under a severe thunderstorm watch, issued at 21:45 UTC and running to 02:00 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 Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:55 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.

Belleville - Scott AFB (BLV), 24 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The St Louis radar (KLSX), 84 km away, was scanning. The volume nearest the touchdown began at 00:05 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 2021 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

18 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.