Tornadoes · United States · Tennessee · 2020

EF0 tornado, Vervilla, Tennessee, August 28, 2020

This EF0 tornado ran 1.5 miles across Warren County on August 28, 2020, touching down at 5:28 PM CDT and reaching 65 yards wide. It killed nobody, and did $5,000 of property damage.

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 mphthis tornado

    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. 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.

The record

Rating
EF0
Date
August 28, 2020
Touchdown
5:28 PM CDT (22:28 UTC)
Lifted
5:31 PM CDT (22:31 UTC)
On the ground
3 minutes
Path length
1.5 miles (2.5 km)
Path width
65 yards (59 m)
Deaths
0
Injuries
0
Property damage
$5,000
County
Warren County
Touchdown point
35.553, -85.903
Lift-off point
35.565, -85.880
Record number
2008281628-01

The damage survey

6 damage points were recorded along this path by NWS OHX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 65 mph.

  • Very old shed was destroyed
  • Corn blow down in convergent narrow path

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

After making landfall in southwest Louisiana on Wednesday, August 26, 2020, Hurricane Laura moved northward into Arkansas and weakened to a tropical storm on Thursday, August 27, then traveled eastward across Tennessee and Kentucky and weakened further to a tropical depression on Friday, August 28. The system brought numerous showers and thunderstorms to Middle Tennessee, some of which became severe and produced several reports of damaging winds along with two weak tornadoes. Rainfall totals across the area ranged from 1 to 3 inches.

A damage survey by Warren County Emergency Management along with video by nearby residents indicate a brief and weak EF-0 tornado intermittently touched down in extreme southwest Warren County between Morrison and Viola. One barn sustained significant damage on Cecil Laxson Road and several trees were blown down along the roadway and in adjacent orchards. Another small barn was destroyed on Fred Hoover Road with a damage path noted through adjacent corn fields. This is the first known tornado to occur in Warren County in the month of August.

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. One was issued for the county at another hour that day.

Issued (UTC)ExpiredProductOffice
18:07 UTC20:47 UTCTornado WatchOHX
22:45 UTC23:00 UTCTornado WarningOHX

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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:00 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.

Nashville Metro, TN (KBNA), 12:00Z

10.5 hours before the tornado, 90 km from the path. August 28, 2020.

Skew-T log-pSkew-T log-p diagram, Nashville Metro, TN at 12:00Z on 2020-08-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 598 joules per kilogram, CIN -32, lifted condensation level 737 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Nashville Metro, TN at 12:00Z on 2020-08-28The 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 152 square meters per square second, 0 to 6 km bulk shear 36 knots.193958Sfc1 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
598 J/kg
Mixed-layer CIN
-32 J/kg
Surface CAPE
1298 J/kg
Mixed-layer LCL
737 m above ground
0-6 km bulk shear
36 kt
0-1 km bulk shear
29 kt
0-1 km storm-relative helicity
152 m²/s²
0-3 km storm-relative helicity
138 m²/s²
Significant tornado parameter
0.4
Supercell composite
3.7
0-3 km lapse rate
5.0 K/km

Open this sounding in Storm Lab

Nashville Metro, TN (KBNA), 00:00Z

1.5 hours after it, 90 km from the path. August 29, 2020.

Skew-T log-pSkew-T log-p diagram, Nashville Metro, TN at 00:00Z on 2020-08-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 11 joules per kilogram, CIN -71, lifted condensation level 671 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Nashville Metro, TN at 00:00Z on 2020-08-29The 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 188 square meters per square second, 0 to 6 km bulk shear 44 knots.193958Sfc1 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
11 J/kg
Mixed-layer CIN
-71 J/kg
Surface CAPE
154 J/kg
Mixed-layer LCL
671 m above ground
0-6 km bulk shear
44 kt
0-1 km bulk shear
34 kt
0-1 km storm-relative helicity
188 m²/s²
0-3 km storm-relative helicity
202 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2
0-3 km lapse rate
4.4 K/km

Open this sounding in Storm Lab

The radar

The Northeast Alabama radar (KHTX), 72 km away, was scanning. The volume nearest the touchdown began at 22:26 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
22:27 UTCTSTM WND DMG3 Wnw ViolaWarren, TNREPORT OF BARN DESTROYED ON CECIL LAXSON RD.
22:27 UTCTORNADO3 Wnw ViolaWarren, TNA DAMAGE SURVEY BY WARREN COUNTY EMA ALONG WITH VIDEO BY NEARBY RESIDENTS INDICATE A VERY BRIEF WEAK EF-0 TORNADO TOUCHED DOWN IN EXTREME SOUTHWEST WARREN COUNTY BETWEEN MORRISON AND VIOLA ALONG CECIL LAXSON ROAD. ONE BA
22:28 UTCTORNADO3 Wnw ViolaWarren, TNUPDATED INFO...A DAMAGE SURVEY BY WARREN COUNTY EMERGENCY MANAGEMENT ALONG WITH VIDEO BY NEARBY RESIDENTS INDICATE A BRIEF WEAK EF-0 TORNADO INTERMITTENTLY TOUCHED DOWN IN SOUTHWEST WARREN COUNTY BETWEEN MORRISON AND VIO
23:10 UTCTSTM WND DMG9 Ene McminnvilleWarren, TNLARGE TREE DOWN BLOCKING ROAD AT 1621 COPENHAVER ROAD. TIME ESTIMATED.

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 TennesseeEvery tornado in Tennessee since 1950Warnings in force in Tennessee nowThe forecast where you are

The other tornadoes of August 28, 2020

12 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 281:26 AM CDTUnratedKingsbury, SD0.425
August 281:27 AM CDTEF1Kingsbury, SD0.625$75,000
August 282:08 AM CDTEF0Deuel, SD0.150
August 282:09 AM CDTEF0Deuel, SD0.220
August 282:09 AM CDTEF0Deuel, SD0.730
August 282:11 AM CDTEF1Deuel, SD0.940
August 286:33 AM CDTEF0Lafayette, MS1.150
August 284:02 PM CDTEF1Winston, AL8.8325
August 284:36 PM CDTEF1Winston, AL2.6100
August 285:27 PM CDTEF1Cullman, AL5.6115
August 285:58 PM CDTEF0Morgan, AL0.240
August 287:24 PM CDTEF0Putnam, TN2.450$15,000

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.