Tornadoes · United States · South Dakota · 1996

F0 tornado, Ortley, South Dakota, May 17, 1996

This F0 tornado ran 0.4 miles across Roberts County on May 17, 1996, touching down at 6:00 PM CDT and reaching 15 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. F040 to 72 mphthis tornado

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. F173 to 112 mph

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. F2113 to 157 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. F3158 to 206 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. F4207 to 260 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. F5261 to 318 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
F0
Date
May 17, 1996
Touchdown
6:00 PM CDT (23:00 UTC)
Path length
0.4 miles (0.6 km)
Path width
15 yards (14 m)
Deaths
0
Injuries
0
County
Roberts County
Touchdown point
45.420, -97.320
Lift-off point
45.420, -97.320
Record number
631

What the Weather Service recorded

A narrow path tornado touched down 8 miles northwest of Ortley. A machine shed roof was blown off and destroyed, and a 2-ton grain dryer was thrown 100 feet. Path length and width were estimated.

A narrow path tornado touched down 9 miles north of Ortley. A shed door was picked up and blown around and 2X4 missle penetrated the roof of a house. This tornado may have been a second touchdown of the tornado seen 8NW Ortley. However, the damage path did not indicate that it was a continuous touchdown. Path length and width were estimated.

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
19:02 UTC20:05 UTCSevere Thunderstorm WarningABR
21:03 UTC22:05 UTCSevere Thunderstorm WarningABR
22:32 UTC23:20 UTCSevere Thunderstorm WarningABR

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. The outlook in force was issued at 06:00 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.

Aberdeen, SD (KABR), 12:00Z

11.0 hours before the tornado, 103 km from the path. May 17, 1996.

Skew-T log-pSkew-T log-p diagram, Aberdeen, SD at 12:00Z on 1996-05-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1289 joules per kilogram, CIN -330, lifted condensation level 656 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, Aberdeen, SD at 12:00Z on 1996-05-17The 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 137 square meters per square second, 0 to 6 km bulk shear 51 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
1289 J/kg
Mixed-layer CIN
-330 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
656 m above ground
0-6 km bulk shear
51 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
137 m²/s²
0-3 km storm-relative helicity
52 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
2.3 K/km

Open this sounding in Storm Lab

Aberdeen, SD (KABR), 00:00Z

1.0 hours after it, 103 km from the path. May 18, 1996.

Skew-T log-pSkew-T log-p diagram, Aberdeen, SD at 00:00Z on 1996-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 214 joules per kilogram, CIN -32, lifted condensation level 653 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 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, Aberdeen, SD at 00:00Z on 1996-05-18The 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 -359 square meters per square second, 0 to 6 km bulk shear 54 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
214 J/kg
Mixed-layer CIN
-32 J/kg
Surface CAPE
338 J/kg
Mixed-layer LCL
653 m above ground
0-6 km bulk shear
54 kt
0-1 km bulk shear
23 kt
0-1 km storm-relative helicity
-359 m²/s²
0-3 km storm-relative helicity
-486 m²/s²
Significant tornado parameter
-0.5
Supercell composite
-3.9
0-3 km lapse rate
5.4 K/km

Open this sounding in Storm Lab

The surface observations

Watertown (ATY), 58 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
21:00 UTC7969330° 9 kt995.6
21:03 UTC300° 8 kt995.6
21:41 UTC360° 4 kt993.6-RA
22:00 UTC777070° 5 kt994.2-RA
22:23 UTC20° 4 kt993.9FG
22:33 UTC240° 36 kt50996.6-RA FG
22:36 UTC290° 32 kt51997-TSRA FG
22:38 UTC290° 28 kt51996.6-TSRA
22:44 UTC290° 30 kt37996.3TSRAPLGR FG
22:46 UTC290° 27 kt37995.9TSRA FG
23:00 UTC5958290° 21 kt34994.2TSRA FG
23:10 UTC290° 22 kt27997.3TS
23:15 UTC290° 19 kt27997.3
23:27 UTC290° 18 kt22997.3
00:00 UTC6563310° 19 kt29996.6TS
00:06 UTC330° 19 kt27995.6

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

The radar

The Aberdeen radar (KABR), 85 km away, was scanning. The volume nearest the touchdown began at 23:01 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 1996 tornado in South DakotaEvery tornado in South Dakota since 1950Warnings in force in South Dakota nowThe forecast where you are

The other tornadoes of May 17, 1996

12 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 174:45 PM CDTF0Codington, SD0.310
May 175:20 PM CDTF0Codington, SD0.310
May 175:39 PM CDTF0Grant, SD0.310
May 175:55 PM CDTF0Day, SD0.410
May 176:03 PM CDTF3Big Stone, SD to MN18.0200$1.5 million
May 176:05 PM CDTF0Roberts, SD0.310
May 176:13 PM CDTF0Marshall, SD0.615
May 176:25 PM CDTF1Richland, ND2.0100$50,000
May 177:10 PM CDTF1Wilkin, MN1.0100$50,000
May 176:58 PM MDTF1Washington, ID5.515$50,000
May 176:00 PM PDTF0Baker, OR0.110
May 1710:30 PM MDTF1Canyon, ID0.320$50,000

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.