Tornadoes · United States · South Dakota · 2017

EF0 tornado, Oelrichs, South Dakota, August 26, 2017

Name: EF0 tornado, Oelrichs, South Dakota, August 26, 2017
Start: 2017-08-26T21:20:00.000Z
End: 2017-08-26T21:21:00.000Z
Location: Oelrichs, South Dakota

This EF0 tornado ran 0.7 miles across Fall River County on August 26, 2017, touching down at 3:20 PM MDT and reaching 10 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 26, 2017
Touchdown: 3:20 PM MDT (21:20 UTC)
Lifted: 3:21 PM MDT (21:21 UTC)
On the ground: 1 minutes
Path length: 0.7 miles (1.1 km)
Path width: 10 yards (9 m)
Deaths: 0
Injuries: 0
County: Fall River County
Touchdown point: 43.059, -103.296
Lift-off point: 43.055, -103.284
Record number: 1708261520-01

What the Weather Service recorded

A thunderstorm became severe over far southern Fall River County and produced a brief rope tornado south of Oelrichs near the Nebraska border.

Tree damage occurred near the intersection of East Ardmore and Harmony Roads.

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. One was issued for the county at another hour that day.

The county was under a severe thunderstorm watch, issued at 20:11 UTC and running to 01:25 UTC.

Issued (UTC)	Expired	Product	Office
20:11 UTC	01:25 UTC	Severe Thunderstorm Watch	UNR
20:47 UTC	21:45 UTC	Severe Thunderstorm Warning	UNR
21:28 UTC	22:01 UTC	Severe Thunderstorm Warning	UNR
21:30 UTC	21:47 UTC	Tornado Warning	UNR

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 Marginal Risk. The outlook in force was issued at 19:58 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.

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 Rapid City, SD wrote its last area forecast discussion before the tornado touched down at Aug 26, 2:57 PM MDT, 23 minutes earlier.

Area forecast discussion, Aug 26, 2:57 PM MDT, 23 minutes before

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
257 PM MDT Sat Aug 26 2017

.DISCUSSION...(This Evening Through Saturday)
Issued at 257 PM MDT Sat Aug 26 2017

Current surface analysis shows cold front now across far western
SD to southeast WY, moving southeastward. Upper level analysis
shows northwesterly flow across the region, with an embedded
shortwave disturbance moving southeast across the western Dakotas.
Strong to severe storms have developed over the eastern slopes of
the Black Hills early this afternoon, moving south- southeast
across parts of southwest SD. Other activity is beginning to
develop over the rest of western SD. Temps are mostly in the 80s
to around 90 degrees, except cooler across rain soaked areas.
Winds are north-northwest behind the cool front, south to
southeast ahead of it.

Active weather will continue across mainly western SD over the next
few hours as showers and storms move southeast across western SD,
where MLCAPE of 1000 to 2000 j/kg resides near and ahead of the cold
front. A severe thunderstorm watch is in effect through the early
evening for much of western and south central SD, with large hail
and eventually strong wind gusts the main threats. Activity will end
from northwest to southeast across the area later this evening and
overnight.

Sunday will be sunny and warm with highs in the 80s, 70s over the
Black Hills. Winds will be northerly early, switching to the east
and southeast in the afternoon and early evening. Next week still
looks to be warm and mainly dry as ridge builds north across the
western US. Isolated storms could return by late in the week,
especially across the Black Hills area. Temperatures will be near to
slightly above average.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Sunday)
Issued At 1156 AM MDT Sat Aug 26 2017

Another round of thunderstorms expected this afternoon, esp from
the Blkhls eastward. Local MVFR-IFR conds, hail, and gusty winds
possible in TS. VFR conditions expected late tonight as
thunderstorms push to the east. Some thunder may linger in south
central SD into early Sunday morning.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

DISCUSSION...26
AVIATION...15

Hazardous weather outlook, Aug 26, 6:02 AM MDT, 9 hours 18 minutes before

Hazardous Weather Outlook
National Weather Service Rapid City SD
602 AM MDT Sat Aug 26 2017

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ057-071-
271300-
Harding-Perkins-Butte-Northern Meade Co Plains-Ziebach-
Northern Black Hills-Northern Foot Hills-Rapid City-
Southern Foot Hills-Central Black Hills-Southern Black Hills-
Custer Co Plains-Pennington Co Plains-Haakon-Fall River-
Oglala Lakota-Jackson-Bennett-Mellette-Todd-Tripp-
Sturgis/Piedmont Foot Hills-Southern Meade Co Plains-
Hermosa Foot Hills-Wyoming Black Hills-Northeastern Crook-
602 AM MDT Sat Aug 26 2017 /702 AM CDT Sat Aug 26 2017/

This Hazardous weather outlook is for portions of south central
South Dakota...the Black Hills of South Dakota...western South
Dakota...northeast Wyoming...and the Black Hills of Wyoming.

.DAY ONE...TODAY AND TONIGHT

There is a chance of thunderstorms today. Severe thunderstorms
will be possible with large hail and damaging winds.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed today.

&&

Stay tuned to NOAA weather radio for further updates...or check
our web site at weather.gov/rapidcity

WYZ054>056-058-271300-
Northern Campbell-Southern Campbell-Western Crook-Weston-
602 AM MDT Sat Aug 26 2017

This Hazardous weather outlook is for portions of northeast
Wyoming.

.DAY ONE...Today and Tonight

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

&&

Stay tuned to NOAA weather radio for further updates...or check
our web site at weather.gov/rapidcity

JC

In the hours before

Local storm report, Aug 26, 1:33 PM MDT, 1 hour 47 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
133 PM MDT SAT AUG 26 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0114 PM     HAIL             4 NE ROCKERVILLE        44.00N 103.31W
08/26/2017  E1.50 INCH       PENNINGTON         SD   NWS EMPLOYEE

            QUARTER SIZE TO PING PONG SIZE HAIL

0131 PM     HAIL             5 WNW HERMOSA           43.86N 103.30W
08/26/2017  E1.50 INCH       CUSTER             SD   TRAINED SPOTTER

            PEA SIZE TO MARBLE SIZE HAIL MOSTLY WITH A FEW PING
            PONG SIZE HAIL MIXED IN.

&&

AFOSCATO

Local storm report, Aug 26, 1:43 PM MDT, 1 hour 37 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
143 PM MDT SAT AUG 26 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0135 PM     HAIL             5 WNW HERMOSA           43.86N 103.30W
08/26/2017  E2.00 INCH       CUSTER             SD   TRAINED SPOTTER

            HAIL COVERING GROUND

0138 PM     HAIL             6 ENE CENTER LAKE       43.84N 103.33W
08/26/2017  M1.50 INCH       CUSTER             SD   TRAINED SPOTTER

            HAIL COVERING GROUND

&&

AFOSCATO

Local storm report, Aug 26, 2:06 PM MDT, 1 hour 14 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
206 PM MDT SAT AUG 26 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0155 PM     HAIL             5 NNW FAIRBURN          43.75N 103.24W
08/26/2017  M1.50 INCH       CUSTER             SD   TRAINED SPOTTER

            PEA TO PINGPONG SIZE HAIL

0155 PM     HAIL             4 NNW FAIRBURN          43.74N 103.25W
08/26/2017  M1.00 INCH       CUSTER             SD   TRAINED SPOTTER

&&

AFOSCATO

Local storm report, Aug 26, 2:19 PM MDT, 1 hour 1 minute before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
219 PM MDT SAT AUG 26 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0100 PM     HAIL             5 SSE RAPID CITY        44.01N 103.20W
08/26/2017  M1.50 INCH       PENNINGTON         SD   COCORAHS

&&

AFOSCATO

Local storm report, Aug 26, 2:22 PM MDT, 58 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
222 PM MDT SAT AUG 26 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0207 PM     HAIL             5 NNW FAIRBURN          43.75N 103.24W
08/26/2017  M1.50 INCH       CUSTER             SD   TRAINED SPOTTER

            SECOND WAVE OF HAIL BEGAN AT 207PM... ENDED AT 217PM

&&

EAGAN

Special weather statement, Aug 26, 2:57 PM MDT, 23 minutes before

Special Weather Statement
National Weather Service Rapid City SD
257 PM MDT SAT AUG 26 2017

SDZ013-014-031-032-073-262145-
Ziebach SD-Pennington Co Plains SD-Southern Meade Co Plains SD-
Haakon SD-Northern Meade Co Plains SD-
257 PM MDT SAT AUG 26 2017

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL HAAKON...
SOUTHWESTERN ZIEBACH...EAST CENTRAL MEADE AND NORTHEASTERN PENNINGTON
COUNTIES UNTIL 345 PM MDT...

At 257 PM MDT, Doppler radar was tracking a strong thunderstorm over
Plainview, or 30 miles south of Faith, moving east at 25 mph.

Nickel size hail will be possible with this storm.

Locations impacted include...
Plainview, Bridger, Howes and Takini School.

A severe thunderstorm watch remains in effect until 1000 PM MDT for
west central South Dakota.

LAT...LON 4450 10226 4468 10221 4464 10166 4437 10174
TIME...MOT...LOC 2057Z 282DEG 22KT 4458 10214

Rudge

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

9.3 hours before the tornado, 117 km from the path. August 26, 2017.

Skew-T log-p

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.

Hodograph

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: 69 J/kg
Mixed-layer CIN: -227 J/kg
Surface CAPE: 250 J/kg
Mixed-layer LCL: 2080 m above ground
0-6 km bulk shear: 31 kt
0-1 km bulk shear: 7 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 110 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0
0-3 km lapse rate: 5.1 K/km

Open this sounding in Storm Lab

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

2.7 hours after it, 117 km from the path. August 27, 2017.

Skew-T log-p

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.

Hodograph

Mixed-layer CAPE: 184 J/kg
Mixed-layer CIN: -182 J/kg
Surface CAPE: 784 J/kg
Mixed-layer LCL: 2420 m above ground
0-6 km bulk shear: 38 kt
0-1 km bulk shear: 4 kt
0-1 km storm-relative helicity: -27 m²/s²
0-3 km storm-relative helicity: 40 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0
0-3 km lapse rate: 6.3 K/km

Open this sounding in Storm Lab

The surface observations

Chadron (CDR), 29 km from the path, in the two hours either side.

Time (UTC)	Temp (°F)	Dew point (°F)	Wind	Gust (kt)	Pressure (mb)	Weather
19:20 UTC			180° 10 kt
19:25 UTC			200° 10 kt	15
19:30 UTC			200° 13 kt	19	1017.6
19:35 UTC			180° 10 kt
19:40 UTC			200° 11 kt
19:45 UTC			200° 13 kt	19
19:50 UTC			190° 13 kt		1016.9
19:53 UTC	90	55	190° 11 kt	20	1016.9
19:55 UTC			190° 8 kt
20:00 UTC			190° 10 kt
20:05 UTC			220° 8 kt
20:10 UTC			200° 14 kt		1017.3
20:15 UTC			170° 11 kt		1017.3
20:20 UTC			160° 7 kt
20:25 UTC			170° 11 kt	16
20:30 UTC			190° 11 kt		1016.9
20:35 UTC			160° 8 kt
20:40 UTC			190° 11 kt
20:45 UTC			170° 10 kt
20:50 UTC			170° 10 kt	16	1016.6
20:53 UTC	92	55	150° 14 kt	20	1016.6
20:55 UTC
21:00 UTC			190° 13 kt
21:05 UTC
21:10 UTC			170° 12 kt		1016.3
21:15 UTC
21:20 UTC	89	55	160° 15 kt		1015.6	VCTS
21:25 UTC
21:30 UTC	88	56	170° 15 kt		1015.6	TS
21:35 UTC
21:40 UTC
21:45 UTC
21:50 UTC			130° 15 kt		1014.9
21:53 UTC	86	55	120° 13 kt		1015.2	TS
21:55 UTC			110° 13 kt
22:00 UTC
22:05 UTC	76	62			1016.9	-TSRA
22:10 UTC					1017.3	RA
22:15 UTC					1017.6	+RA
22:20 UTC					1017.3	-RA
22:22 UTC	69	60			1016.9	-TSRA
22:25 UTC					1016.6	-RA
22:30 UTC					1016.9	-RA
22:35 UTC					1016.9
22:37 UTC	69	59			1016.9	VCTS
22:40 UTC					1016.9
22:45 UTC					1016.9
22:50 UTC					1016.6
22:53 UTC	69	59			1016.6	VCTS
22:55 UTC					1016.6
23:00 UTC					1016.6
23:05 UTC					1016.3
23:10 UTC					1016.3
23:11 UTC	74	57			1016.3
23:15 UTC

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

The radar

The Rapid City radar (KUDX), 124 km away, was scanning. The volume nearest the touchdown began at 21:22 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)	Report	Where	County	Remark
21:16 UTC	HAIL 1	8 E Smithwick	Fall River, SD
21:20 UTC	TORNADO	9 Ssw Oelrichs	Fall River, SD	BRIEF ROPE TORNADO TOUCHED DOWN AROUND 320 PM. SOME TREE DAMAGE NEAR INTERSECTION OF HARMONY AND ARDMORE ROADS.
21:34 UTC	HAIL 0.88	13 Nw Slim Butte	Oglala Lakota, SD

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

This ground now

The live radar over the track Every 2017 tornado in South Dakota Every tornado in South Dakota since 1950 Warnings in force in South Dakota now The forecast where you are

The other tornadoes of August 26, 2017

12 more were confirmed in the United States that day.

Date	Time	Rating	Where	Path (mi)	Width (yd)	Damage
August 26	2:10 AM CDT	EF0	Wharton, TX	1.4	30
August 26	2:12 AM CDT	EF0	Fort Bend, TX	0.1	30	$30,000
August 26	4:30 AM CDT	EF0	Harris, TX	1.0	30	$100,000
August 26	5:00 AM CDT	EF1	Fort Bend, TX	0.9	50	$1.3 million
August 26	8:05 AM CDT	EF0	Brazos, TX	0.2	20
August 26	12:22 PM CDT	EF0	Cameron Parish, LA	1.7	25	$7,000
August 26	3:50 PM CDT	EF1	Harris, TX	0.9	50	$500,000
August 26	4:20 PM CDT	EF0	Harris, TX	0.5	50	$30,000
August 26	5:23 PM CDT	EF0	Wharton, TX	0.5	30	$50,000
August 26	8:15 PM CDT	EF1	Fort Bend, TX	5.8	100	$2.0 million
August 26	9:19 PM EDT	EF0	Manatee, FL	0.3	50	$20,000
August 26	12:00 AM CDT	EF0	Harris, TX	0.0	30	$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.