EF1 tornado, Stephan, South Dakota, June 18, 2014

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 mphthis tornado

   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

EF1

Date

June 18, 2014

Touchdown

6:05 PM CDT (23:05 UTC)

Lifted

6:15 PM CDT (23:15 UTC)

On the ground

10 minutes

Path length

0.7 miles (1.2 km)

Path width

40 yards (37 m)

Deaths

0

Injuries

0

County

Hyde County

Touchdown point

44.251, -99.367

Lift-off point

44.261, -99.367

Record number

1406181705-01

5 damage points were recorded along this path by NWS ABR, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 105 mph.

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

A surface low pressure area in southeast South Dakota with a warm front extending to the southeast pushed north and brought numerous severe thunderstorms to parts of central and northeast South Dakota. Large hail, damaging winds, flash flooding, along with several tornadoes occurred with these storms.

A tornado touched down east of Stephan damaging two homes. The main home at the residence had part of its metal roof taken off, while a secondary home lost its entire roof structure. A wooden barn had its main door blown in resulting in a lifting of the roof structure. This allowed the exterior walls to collapse with the roof then settling back down on the debris. A metal machine shed was destroyed along with a semi-tractor trailer blown over on its side. As the tornado continued north, a tree grove suffered extensive damage with numerous trees being topped and large branches broken off.

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

3 minutes of warning. NWS ABR issued a tornado warning for this county at 23:02 UTC, 3 minutes before the tornado touched down, in force until 23:30 UTC.

The county was under a tornado watch, issued at 18:29 UTC and running to 03:00 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 0.10 chance of a tornado within 25 miles. The outlook in force was issued at 19:40 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.

Chamberlain (9V9), 55 km from the path, in the two hours either side.

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

The Aberdeen radar (KABR), 153 km away, was scanning. The volume nearest the touchdown began at 23:02 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 2014 tornado in South DakotaEvery tornado in South Dakota since 1950Warnings in force in South Dakota nowThe forecast where you are

18 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.