EF0 tornado, Holabird to Highmore Arpt, South Dakota, August 23, 2018

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.

Rating

EF0

Date

August 23, 2018

Touchdown

6:27 PM CDT (23:27 UTC)

Lifted

6:33 PM CDT (23:33 UTC)

On the ground

6 minutes

Path length

0.6 miles (1.0 km)

Path width

70 yards (64 m)

Deaths

0

Injuries

0

County

Hyde County

Touchdown point

44.787, -99.469

Lift-off point

44.796, -99.464

Record number

1808231727-01

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

• Hay bale destroyed and thrown to the northeast.
• Metal fence post snapped at the base.
• Metal fans missing from windmill.
• 4-wheeler was tossed into metal gate and then into the side of the barn.

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

Severe thunderstorms developed near a surface low pressure area and dryline in central South Dakota during the late afternoon and evening hours. Very large hail up to three inches in diameter, damaging winds to seventy mph, along with a couple tornadoes occurred in central and north central South Dakota.

The tornado started on the west side of a ranch and threw a 4-wheeler into a barn. There was additional damage to trees and the roof of a barn at the ranch. The tornado moved across an open field and damaged a calf shed. It then crossed 180th street and 331st avenue and moved through a corn field. Many corn stalks were flattened in a 50 yard wide path before entering an open field and then crossing a hay field destroying a hay bale before dissipating.

Based off spotter photos and high resolution satellite imagery, the tornado tracked for over a half mile through a center pivot farm field around 19 miles north of Highmore.

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

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.

The county was under a severe thunderstorm watch, issued at 23:01 UTC and running to 03:47 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 19:53 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.

The Aberdeen radar (KABR), 111 km away, was scanning. The volume nearest the touchdown began at 23:28 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 2018 tornado in South DakotaEvery tornado in South Dakota since 1950Warnings in force in South Dakota nowThe forecast where you are

1 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.