Tornadoes · United States · Illinois · 2020

Unrated tornado, Palmyra Zelmer Arpt, Illinois, July 15, 2020

This Unrated tornado ran 0.1 miles across Macoupin County on July 15, 2020, touching down at 4:47 PM CDT and reaching 15 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
July 15, 2020
Touchdown
4:47 PM CDT (21:47 UTC)
Lifted
4:48 PM CDT (21:48 UTC)
On the ground
1 minutes
Path length
0.1 miles (0.2 km)
Path width
15 yards (14 m)
Deaths
0
Injuries
0
County
Macoupin County
Touchdown point
39.406, -89.928
Lift-off point
39.408, -89.926
Record number
2007151547-01

The damage survey

4 damage points were recorded along this path by NWS LSX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 85 mph.

  • Brief tornado touchdown in a field. Two spotters reported it, one with a picture. The tornado did not hit any damage indicators this it will be labeled as an EF-unknown.
  • Crops are flattened in a convergent pattern.

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

A strong cold front moved through the region triggering showers and storms. Some of the storms produced damaging winds and a couple of tornadoes.

Two spotters reported a tornado briefly touched down in a field verified with a picture. This tornado touched down northeast of Hettick, IL, southwest of Otter Lake. The tornado was very short lived and did not damage any rating indicators, thus it will be labeled an EF-unknown.

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

The warnings

9 minutes of warning. NWS LSX issued a tornado warning for this county at 21:38 UTC, 9 minutes before the tornado touched down, in force until 22:01 UTC.

The county was under a tornado watch, issued at 19:12 UTC and running to 00:32 UTC.

Issued (UTC)ExpiredProductOffice
19:12 UTC00:32 UTCTornado WatchLSX
21:38 UTC22:01 UTCTornado WarningLSX
21:48 UTC22:08 UTCSevere Thunderstorm WarningLSX
22:02 UTC22:10 UTCSevere Thunderstorm WarningLSX

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 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:52 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

9.8 hours before the tornado, 140 km from the path. July 15, 2020.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 12:00Z on 2020-07-15Temperature 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 -72859, lifted condensation level 1529 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 2020-07-15The 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 30 square meters per square second, 0 to 6 km bulk shear 20 knots.1939Sfc1 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
-72859 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1529 m above ground
0-6 km bulk shear
20 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
30 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
3.7 K/km

Open this sounding in Storm Lab

The radar

The Lincoln radar (KILX), 97 km away, was scanning. The volume nearest the touchdown began at 21:44 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
21:25 UTCTSTM WND DMG2 Nw AltonMadison, ILSEVERAL TREES DOWN WEST OF THE BEND OF HIGHWAY 67. TREES WERE REPORTED TO BE OVER NEIGHBORHOOD ROADS. A HOME SUFFERED A PARTIALLY REMOVED ROOF AND FENCE LINE BLOWN OVER NEAR GLOVER AND ELM STREET. ONE VEHICLE SUFFERED DA
21:35 UTCTORNADO5 W LoamiSangamon, ILMINOR DAMAGE TO TREES.
21:47 UTCTORNADO4 Ese PalmyraMacoupin, ILTWO SPOTTERS REPORTED A TORNADO BRIEFLY TOUCHED DOWN IN A FIELD VERIFIED WITH A PICTURE. THIS TORNADO TOUCHED DOWN NORTHEAST OF HETTICK, IL, SOUTHWEST OF OTTER CREEK. THE TORNADO WAS VERY SHORT LIVED AND DID NOT DAMAGE A
21:58 UTCTORNADO3 Se Mount OliveMontgomery, ILA COMBINATION OF A GROUND SURVEY AND SATELLITE DATA SHOWS AN INTERMITTENT, 3.2 MILE TORNADO PATH THAT BEGAN JUST SOUTH OF PRANGE AVENUE. IT SNAPPED AND UPROOTED SOME TREES NEAR A RESIDENCE NORTH OF PRANGE AVENUE. SATELLI
22:03 UTCTSTM WND DMGWalshvilleMontgomery, ILLARGE TREE DOWN IN THE TOWN OF WALSHVILLE, IL. TIME ESTIMATED FROM RADAR.
22:05 UTCTORNADO2 Nne WalshvilleMontgomery, ILA COMBINATION OF A GROUND SURVEY AND SATELLITE DATA SUGGESTS A BRIEF, WEAK TORNADO TOUCHED DOWN NORTHEAST OF WALSHVILLE, IL. THE TORNADO FIRST TOUCHED DOWN IN A CORN FIELD WEST OF DURBIN ROAD. THE TORNADO THEN CONTINUED
22:15 UTCTSTM WND DMG1 Sse ButlerMontgomery, ILLARGE TREE DOWN SOUTH OF BUTLER. TIME ESTIMATED FROM RADAR.
22:15 UTCTSTM WND DMG1 Sw HillsboroMontgomery, ILLARGE TREE OVER THE ROADWAY IN HILLSBORO. TIME ESTIMATED FROM RADAR.
22:20 UTCTORNADO4 N FarmersvilleMontgomery, ILA TORNADO DEVELOPED ABOUT 3 MILES NORTH-NORTHWEST OF FARMERSVILLE, ILLINOIS NEAR THE INTERSECTION OF ROVEY LANE AND EAST 1ST ROAD. A FEW STORM CHASERS CAPTURED VIDEO OF THE TORNADO AS IT MOVED NORTHEAST AND THEN NORTH TO
23:30 UTCHEAVY RAIN 1.1JacksonvilleMorgan, ILREPORTED IN 25 MINUTES
00:00 UTCHEAVY RAIN 2.714 W SpringfieldSangamon, IL

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

This ground now

The live radar over the trackEvery 2020 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

The other tornadoes of July 15, 2020

9 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 151:37 PM CDTUnratedTazewell, IL0.110
July 151:45 PM CDTUnratedTazewell, IL0.110
July 154:04 PM CDTUnratedMcLean, IL0.210
July 154:28 PM CDTEF0Morgan, IL4.150$20,000
July 154:58 PM CDTEF0Montgomery, IL3.275
July 155:05 PM CDTEF0Montgomery, IL0.650
July 155:18 PM CDTEF0Sangamon, IL4.5300
July 156:03 PM MDTEF0Socorro, NM0.330
July 1511:40 PM CDTEF1Posey, IN4.380$95,000

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.