Tornadoes · United States · Arkansas · 2017

EF0 tornado, Black Rock, Arkansas, March 7, 2017

This EF0 tornado ran 0.3 miles across Lawrence County on March 7, 2017, touching down at 2:37 AM CST and reaching 100 yards wide. It killed nobody, and did $60,000 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
March 7, 2017
Touchdown
2:37 AM CST (08:37 UTC)
Lifted
2:38 AM CST (08:38 UTC)
On the ground
1 minutes
Path length
0.3 miles (0.6 km)
Path width
100 yards (91 m)
Deaths
0
Injuries
0
Property damage
$60,000
County
Lawrence County
Touchdown point
36.118, -91.102
Lift-off point
36.119, -91.096
Record number
1703070237-01

What the Weather Service recorded

A cold front produced a line of severe thunderstorms during the early morning hours of March 7th.

Damage was primarily to metal roofing and some farm buildings and trees. Peak winds estimated at 75 mph.

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.

The county was under a tornado watch, issued at 03:21 UTC and running to 10:52 UTC.

Issued (UTC)ExpiredProductOffice
03:21 UTC10:52 UTCTornado WatchMEG
06:15 UTC10:56 UTCWind AdvisoryMEG
08:19 UTC09:00 UTCSevere Thunderstorm WarningMEG

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 General Thunderstorms Risk. The outlook in force was issued at 05:54 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.

Little Rock, AR (KBYH), 00:00Z

8.6 hours before the tornado, 177 km from the path. March 7, 2017.

Skew-T log-pSkew-T log-p diagram, Little Rock, AR at 00:00Z on 2017-03-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 208 joules per kilogram, CIN -17, lifted condensation level 755 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, Little Rock, AR at 00:00Z on 2017-03-07The 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 338 square meters per square second, 0 to 6 km bulk shear 48 knots.19395878Sfc1 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
208 J/kg
Mixed-layer CIN
-17 J/kg
Surface CAPE
832 J/kg
Mixed-layer LCL
755 m above ground
0-6 km bulk shear
48 kt
0-1 km bulk shear
36 kt
0-1 km storm-relative helicity
338 m²/s²
0-3 km storm-relative helicity
509 m²/s²
Significant tornado parameter
0.5
Supercell composite
7.4
0-3 km lapse rate
6.5 K/km

Open this sounding in Storm Lab

Little Rock, AR (KBYH), 12:00Z

3.4 hours after it, 177 km from the path. March 7, 2017.

Skew-T log-pSkew-T log-p diagram, Little Rock, AR at 12:00Z on 2017-03-07Temperature 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 -86878, lifted condensation level 808 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, Little Rock, AR at 12:00Z on 2017-03-07The 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 -314 square meters per square second, 0 to 6 km bulk shear 59 knots.19395878Sfc1 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
-86878 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
808 m above ground
0-6 km bulk shear
59 kt
0-1 km bulk shear
32 kt
0-1 km storm-relative helicity
-314 m²/s²
0-3 km storm-relative helicity
-249 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
2.2 K/km

Open this sounding in Storm Lab

The surface observations

Walnut Ridge (Awos) (ARG), 16 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
06:45 UTC180° 26 kt311011.2
06:55 UTC64.459190° 25 kt331011.2
07:05 UTC180° 25 kt341011.2
07:15 UTC64.459190° 26 kt341010.8
07:20 UTC 341010.8
07:25 UTC190° 25 kt341011.2
07:35 UTC64.459190° 26 kt321011.2
07:45 UTC190° 22 kt321011.2
07:55 UTC64.459190° 22 kt301010.8
08:00 UTC180° 24 kt291010.5
08:05 UTC180° 21 kt311010.5
08:10 UTC180° 25 kt311010.5
08:15 UTC64.459180° 25 kt301010.2
08:20 UTC180° 21 kt291009.8
08:30 UTC180° 26 kt311009.5
08:35 UTC64.459180° 25 kt331009.5VCTS
08:40 UTC180° 25 kt331009.5
08:45 UTC 35
08:50 UTC 1012.9
08:55 UTC60.853.6280° 21 kt571012.9VCTS
09:00 UTC260° 12 kt341013.2
09:05 UTC250° 11 kt181013.5
09:10 UTC260° 10 kt1013.9
09:15 UTC57.251.8270° 9 kt1013.9VCTS
09:20 UTC 141013.5
09:25 UTC 1013.2
09:35 UTC55.451.8290° 11 kt181013.2VCTS
09:40 UTC310° 17 kt231013.2
09:45 UTC300° 15 kt251013.9
09:50 UTC300° 11 kt251013.9
09:55 UTC53.648.2310° 11 kt1013.5TS
10:00 UTC310° 11 kt1013.9
10:05 UTC350° 10 kt161014.2
10:10 UTC 1014.6
10:15 UTC53.648.2330° 16 kt221014.9
10:20 UTC310° 14 kt221015.6
10:25 UTC310° 14 kt1015.6
10:30 UTC310° 15 kt1015.6
10:35 UTC51.846.4310° 13 kt1015.9VCTS

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

The radar

The Memphis radar (KNQA), 140 km away, was scanning. The volume nearest the touchdown began at 08:35 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
08:28 UTCTSTM WND DMG1 N SmithvilleLawrence, ARSOME TREES AND POWER LINES WERE BLOWN DOWN. A COUPLE OF BARNS WERE DAMAGED.
08:35 UTCTSTM WND DMGBlack RockLawrence, ARMANY TWISTED/UPROOTED TREES, TIN ROOVES PEELED OFF CHICKEN COOPS. TIME ESTIMATED BASED ON RADAR.
08:45 UTCTSTM WND DMGBlack RockLawrence, ARLARGE TREE DOWN HWY 361 AND COUNTY ROAD 216 SOUTH OF BLACK ROCK
08:55 UTCTSTM WND DMGBlack RockLawrence, ARTREES AND POWER LINES DOWN ALONG COUNTY ROAD 210 AND CEMENTARY ROAD NEAR BLACK ROCK.
08:55 UTCTSTM WND DMGCollege CityLawrence, ARTWO TREES DOWN WITH ONE ON A HOUSE ON FACULTY DRIVE. NO INJURIES REPORTED.
08:55 UTCFLASH FLOODBlack RockLawrence, ARWATER OVER ROAD AT HWY 361 AND COUNTY ROAD 216.
08:55 UTCTSTM WND GST 66Walnut RidgeLawrence, AR

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

This ground now

The live radar over the trackEvery 2017 tornado in ArkansasEvery tornado in Arkansas since 1950Warnings in force in Arkansas nowThe forecast where you are

The other tornadoes of March 7, 2017

7 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
March 712:00 AM CSTEF1Tazewell, IL7.4150$175,000
March 712:09 AM CSTEF2Tazewell, IL2.8200$120,000
March 712:14 AM CSTEF0Bureau, IL0.325
March 712:29 AM CSTEF0Jefferson, MO2.680
March 712:39 AM CSTEF0Jefferson, MO1.175
March 712:50 AM CSTEF1Macoupin, IL12.9100
March 71:14 AM CSTEF1Montgomery, IL7.2100

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.