Tornadoes · United States · Illinois · 2021

Unrated tornado, Humboldt, Illinois, April 28, 2021

This Unrated tornado ran 0.1 miles across Coles County on April 28, 2021, touching down at 7:36 PM CDT and reaching 25 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.

  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 mph

    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. Unratedthis tornado

    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
Unrated
Date
April 28, 2021
Touchdown
7:36 PM CDT (00:36 UTC)
Lifted
7:37 PM CDT (00:37 UTC)
On the ground
1 minutes
Path length
0.1 miles (0.2 km)
Path width
25 yards (23 m)
Deaths
0
Injuries
0
County
Coles County
Touchdown point
39.633, -88.352
Lift-off point
39.634, -88.351
Record number
2104281836-01

The damage survey

2 damage points were recorded along this path by NWS ILX, in the Damage Assessment Toolkit the survey teams carry. The highest wind the damage implies is 60 mph.

  • End of tornado. On ground a few seconds.
  • Chaser reported brief tornado touchdown in open field. No damage.

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

An outflow boundary from morning convection across north-central Illinois settled southward to just south of the I-72 corridor by the early evening of April 28th. The atmosphere was only modestly unstable and sheared: however, enough surface-based vorticity was present near the boundary to trigger a couple rotating cells. One of the cells produced a brief very weak tornado northwest of Humboldt in Coles County.|No damage occurred.

A very weak tornado briefly touched down in a field northwest of Humboldt at 7:36 PM CDT. The tornado quickly dissipated before causing any damage.

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.

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 Marginal Risk. The outlook in force was issued at 19:33 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), 00:00Z

0.6 hours before the tornado, 61 km from the path. April 29, 2021.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 00:00Z on 2021-04-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 145 joules per kilogram, CIN -12, lifted condensation level 1042 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Lincoln, IL at 00:00Z on 2021-04-29The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 98 square meters per square second, 0 to 6 km bulk shear 42 knots.1939587897117Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
145 J/kg
Mixed-layer CIN
-12 J/kg
Surface CAPE
700 J/kg
Mixed-layer LCL
1042 m above ground
0-6 km bulk shear
42 kt
0-1 km bulk shear
17 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
176 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.4
0-3 km lapse rate
6.7 K/km

Open this sounding in Storm Lab

Lincoln, IL (KILX), 12:00Z

11.4 hours after it, 61 km from the path. April 29, 2021.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 12:00Z on 2021-04-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -75906, lifted condensation level 449 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Lincoln, IL at 12:00Z on 2021-04-29The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity -17 square meters per square second, 0 to 6 km bulk shear 70 knots.1939587897117Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-75906 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
449 m above ground
0-6 km bulk shear
70 kt
0-1 km bulk shear
5 kt
0-1 km storm-relative helicity
-17 m²/s²
0-3 km storm-relative helicity
32 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.5 K/km

Open this sounding in Storm Lab

The surface observations

Mattoon/Charlest (MTO), 18 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
00:12 UTC69.864.4160° 7 kt1010.8-RA
01:01 UTC6862.6180° 10 kt1010.2-RA
01:58 UTC66.264.4170° 12 kt191009.8

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

The radar

The Lincoln radar (KILX), 102 km away, was scanning. The volume nearest the touchdown began at 00:38 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)ReportWhereCountyRemark
00:36 UTCTORNADO3 Nw HumboldtColes, ILCORRECTS PREVIOUS TORNADO REPORT FROM 3 NW HUMBOLDT. TOUCHED DOWN IN OPEN FIELD. NO DAMAGE SEEN.
00:37 UTCTORNADO3 Nw HumboldtColes, ILTOUCHED DOWN IN OPEN FIELD. NO DAMAGE SEEN.

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

This ground now

The live radar over the trackEvery 2021 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

The other tornadoes of April 28, 2021

10 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 286:01 AM CDTUnratedAdair, OK1.5100
April 286:06 AM CDTEF1Adair, OK7.1225$50,000
April 289:30 AM CDTEF0Taney, MO0.150$25,000
April 289:37 AM CDTEF0Taney, MO0.650$125,000
April 289:55 AM CDTEF0Christian, MO0.450$5,000
April 2810:57 AM CDTEF1Pittsburg, OK7.4300$25,000
April 2811:13 AM CDTEF0Douglas, MO1.9100$250,000
April 282:50 PM CDTEF1Bollinger, MO3.4225
April 286:53 PM CDTEF1Henry, TN6.74001$600,000
April 287:33 PM CDTEF1Medina, TX1.8600$500,000

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.