Tornadoes · United States · South Dakota · 2018
EF0 tornado, Holabird to Highmore Arpt, South Dakota, August 23, 2018
From Holabird to Highmore Arpt, this EF0 tornado ran 1.8 miles across Hyde County on August 23, 2018, touching down at 6:14 PM CDT and reaching 50 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.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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 23, 2018
- Touchdown
- 6:14 PM CDT (23:14 UTC)
- Lifted
- 6:23 PM CDT (23:23 UTC)
- On the ground
- 9 minutes
- Path length
- 1.8 miles (2.9 km)
- Path width
- 50 yards (46 m)
- Deaths
- 0
- Injuries
- 0
- County
- Hyde County
- Touchdown point
- 44.774, -99.541
- Lift-off point
- 44.794, -99.517
- Record number
- 1808231714-01
The damage survey
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.
What the Weather Service recorded
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.
What forecasters said that day
The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Aberdeen, SD wrote its last area forecast discussion before the tornado touched down at Aug 23, 3:35 PM CDT, 2 hours 39 minutes earlier.
Area forecast discussion, Aug 23, 3:35 PM CDT, 2 hours 39 minutes before
Area Forecast Discussion National Weather Service Aberdeen SD 335 PM CDT Thu Aug 23 2018 .SHORT TERM...(This Evening through Friday Afternoon) Issued at 335 PM CDT Thu Aug 23 2018 Some initial short wave trough scattered showers/isolated storms were lifting northeast this afternoon through north central into northeast SD. These will continue to lift in ND through the afternoon. The main area of convection was moving into western SD this afternoon with a jet streak/short wave trough coming around the base of the larger closed upper low pressure area. The surface analyses showed a low pressure area near the PIR area with a warm front extending south southeast from it. As this short wave trough/upper low pressure area moves east tonight, expect showers and thunderstorms to develop/expand eastward across our cwa. There remains a slight risk of severe weather mainly west of the James Valley into this evening. East of the James Valley has little to no risk with stable ll lapse rates along with the cooler air and low clouds. Central and north central SD will have the best chances where low and mid level lapse rates are better along with more sunshine and instability. Although, the deep layer shear was marginal this afternoon generally less than 30 knots for the 0-6km shear. Made adjustments to weather and pops through the night into Friday. Low clouds should remain across much of the east into Friday. Left the pops in for the eastern cwa for Friday as the upper low pressure area moves east and winds become northwest over the entire cwa. It will remain cooler than average across the east with mid 70s for highs. Central South Dakota should be mostly sunny on Friday with mid 80s for highs. .LONG TERM...(Friday Evening through Thursday) Issued at 335 PM CDT Thu Aug 23 2018 The main focus for this forecast period will be chances of precipitation, mainly from the end of the week through early next week. Some weak upper level ridging is expected to be in place across the Dakotas as the period begins, but it will be short lived. An upper level trough is progged to work from the PAC NW toward our region during the weekend. Model consensus indicates that it will be mostly weak in nature. The surface reflection during the weekend shows a cold front will slide through the region during the middle of the weekend. Low end chances for showers and storms will be scattered across the cwa by Saturday night through Sunday. A stronger mid level trough is expected to slide into the region by late in the weekend through Tuesday. A surface low and associated frontal boundaries are anticipated to move through the area Sunday night through Tuesday. Higher chances for precip will exist in our cwa during that time. Temperature trends this period look to remain at or above normal through early next week. After this system moves through early next week, temperatures should cool to near to slightly below normal for late August. && .AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon) Issued at 101 PM CDT Thu Aug 23 2018 Surface front will bring a few showers and thunderstorms through the TAF period. Some of these storms may be severe. Expect spotty MVFR conditions associated with these storms lowering cigs/vis this afternoon and evening. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && SHORT TERM...Mohr LONG TERM...Vipond AVIATION...ALD
Hazardous weather outlook, Aug 23, 4:33 AM CDT, 13 hours 41 minutes before
Hazardous Weather Outlook National Weather Service Aberdeen SD 433 AM CDT Thu Aug 23 2018 SDZ003>005-009-010-015>017-033>037-045-048-051-240945- Corson-Campbell-McPherson-Walworth-Edmunds-Dewey-Potter-Faulk- Stanley-Sully-Hughes-Hyde-Hand-Jones-Lyman-Buffalo- 433 AM CDT Thu Aug 23 2018 /333 AM MDT Thu Aug 23 2018/ This Hazardous Weather Outlook is for central South Dakota and north central South Dakota. .DAY ONE...Today and tonight. Thunderstorms are possible this afternoon through tonight. A few storms could become strong to severe late this afternoon through this evening, mainly between the Missouri River to the James River. Strong winds and large hail will be the main threats, along with brief heavy rain. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation may be requested. Weather spotters are encouraged to submit reports to the National Weather Service in Aberdeen. The public can submit reports on our web page, Facebook page, or our Twitter feed. MNZ039-046-SDZ006>008-011-018>023-240945- Traverse-Big Stone-Brown-Marshall-Roberts-Day-Spink-Clark-Codington- Grant-Hamlin-Deuel- 433 AM CDT Thu Aug 23 2018 This Hazardous Weather Outlook is for west central Minnesota and northeast South Dakota. .DAY ONE...Today and tonight. Thunderstorms are possible this afternoon through tonight. A few storms could become strong to severe late this afternoon through this evening, mainly between the Missouri River to the James River. Strong winds and large hail will be the main threats, along with brief heavy rain. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Thunderstorms will be possible Friday. However, severe weather is not expected. .SPOTTER INFORMATION STATEMENT... Spotter activation may be requested. Weather spotters are encouraged to submit reports to the National Weather Service in Aberdeen. The public can submit reports on our web page, Facebook page, or our Twitter feed. KF
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.
Aberdeen, SD (KABR), 12:00Z
11.2 hours before the tornado, 90 km from the path. August 23, 2018.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- -90835 J/kg
- Surface CAPE
- 0 J/kg
- Mixed-layer LCL
- 895 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km bulk shear
- 17 kt
- 0-1 km storm-relative helicity
- 96 m²/s²
- 0-3 km storm-relative helicity
- 223 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 2.6 K/km
Aberdeen, SD (KABR), 00:00Z
0.8 hours after it, 90 km from the path. August 24, 2018.
- Mixed-layer CAPE
- 1172 J/kg
- Mixed-layer CIN
- -108 J/kg
- Surface CAPE
- 2434 J/kg
- Mixed-layer LCL
- 816 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km bulk shear
- 13 kt
- 0-1 km storm-relative helicity
- 178 m²/s²
- 0-3 km storm-relative helicity
- 227 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 5.3
- 0-3 km lapse rate
- 5.6 K/km
The surface observations
Pierre (PIR), 75 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 00:00 UTC |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Aberdeen radar (KABR), 115 km away, was scanning. The volume nearest the touchdown began at 23:11 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.
This ground now
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
The other tornadoes of August 23, 2018
1 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| August 23 | 6:27 PM CDT | EF0 | Hyde, SD | 0.6 | 70 |
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.