Tornadoes · United States · South Dakota · 2015

EF1 tornado, Cheyenne Crossing, South Dakota, August 8, 2015

This EF1 tornado ran 1.4 miles across Lawrence County on August 8, 2015, touching down at 2:50 PM MDT and reaching 33 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 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.

The record

Rating
EF1
Date
August 8, 2015
Touchdown
2:50 PM MDT (20:50 UTC)
Lifted
2:53 PM MDT (20:53 UTC)
On the ground
3 minutes
Path length
1.4 miles (2.3 km)
Path width
33 yards (30 m)
Deaths
0
Injuries
0
Property damage
$5,000
County
Lawrence County
Touchdown point
44.369, -103.987
Lift-off point
44.382, -103.964
Record number
1508081450-01

The damage survey

5 damage points were recorded along this path by NWS UNR, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 100 mph.

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

A severe thunderstorm developed over the northern Black Hills and tracked eastward across Meade County and southern Ziebach County. The storm produced large hail and wind gusts over 60 mph across the area and a brief tornado southwest of Spearfish.

A small tornado touched down west of Iron Creek Lake. It blew down and snapped aspen, birch, and ponderosa pine trees.

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.

Issued (UTC)ExpiredProductOffice
20:28 UTC21:15 UTCSevere Thunderstorm WarningUNR
21:05 UTC22:00 UTCSevere Thunderstorm WarningUNR
21:05 UTC02:05 UTCSevere Thunderstorm WatchUNR

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 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 20:01 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.

Rapid City, SD (KRAP), 12:00Z

8.8 hours before the tornado, 94 km from the path. August 8, 2015.

Skew-T log-pSkew-T log-p diagram, Rapid City, SD at 12:00Z on 2015-08-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 9 joules per kilogram, CIN -163, lifted condensation level 1700 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, Rapid City, SD at 12:00Z on 2015-08-08The 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 68 square meters per square second, 0 to 6 km bulk shear 40 knots.1939587897Sfc1 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
9 J/kg
Mixed-layer CIN
-163 J/kg
Surface CAPE
51 J/kg
Mixed-layer LCL
1700 m above ground
0-6 km bulk shear
40 kt
0-1 km bulk shear
11 kt
0-1 km storm-relative helicity
68 m²/s²
0-3 km storm-relative helicity
61 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.8 K/km

Open this sounding in Storm Lab

Rapid City, SD (KRAP), 00:00Z

3.2 hours after it, 94 km from the path. August 9, 2015.

Skew-T log-pSkew-T log-p diagram, Rapid City, SD at 00:00Z on 2015-08-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 60 joules per kilogram, CIN -124, lifted condensation level 1949 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, Rapid City, SD at 00:00Z on 2015-08-09The 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 99 square meters per square second, 0 to 6 km bulk shear 41 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
60 J/kg
Mixed-layer CIN
-124 J/kg
Surface CAPE
157 J/kg
Mixed-layer LCL
1949 m above ground
0-6 km bulk shear
41 kt
0-1 km bulk shear
12 kt
0-1 km storm-relative helicity
99 m²/s²
0-3 km storm-relative helicity
272 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
7.0 K/km

Open this sounding in Storm Lab

The radar

The Rapid City radar (KUDX), 95 km away, was scanning. The volume nearest the touchdown began at 20:51 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
20:47 UTCTSTM WND DMG8 Nw Cheyenne CrossingLawrence, SDPINE... BIRCH... AND ASPEN TREES 10 TO 12 IN DIAMETER DOWN ON IRON CREEK LAKE ROAD.
21:10 UTCHAIL 14 Se Downtown SpearfishLawrence, SDREPORT VIA SHAVE PROJECT
21:30 UTCHAIL 1.254 W WhitewoodLawrence, SDHAIL COVERED THE GROUND.
21:38 UTCHAIL 15 Sse WhitewoodLawrence, SDREPORT VIA SHAVE PROJECT
22:05 UTCTSTM WND DMG5 E Downtown SturgisMeade, SDSEVERAL 1 1/2 INCH METAL TENT PIPES BENT OR BROKEN AT BUFFALO CHIP CAMPGROUNDS
22:05 UTCTSTM WND GST 467 E Downtown SturgisMeade, SD
22:05 UTCHAIL 0.755 E Downtown SturgisMeade, SDHAIL RANGED FROM PEA TO PENNY SIZE. COVERING THE GROUND AT BUFFALO CHIP CAMPGROUND
22:05 UTCHAIL 14 Ene Downtown SturgisMeade, SDREPORT VIA SHAVE PROJECT
22:09 UTCTSTM WND GST 502 Nnw Saint OngeLawrence, SD
22:09 UTCHEAVY RAIN 1.12 Nnw Saint OngeLawrence, SD
22:15 UTCTSTM WND GST 606 Ne Downtown SturgisMeade, SD

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

This ground now

The live radar over the trackEvery 2015 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 8, 2015

4 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 82:18 PM CDTEF0Gulf, FL0.550
August 84:25 PM CDTEF1Saint Louis, MN1.6110
August 85:15 PM CDTEF0Hodgeman, KS0.250
August 88:55 PM CDTEF1Pawnee, NE2.2238

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.