Tornadoes and Hail in South Dakota, May 12, 2009

Name: Tornadoes and Hail in South Dakota, May 12, 2009
Start: 2009-05-12T15:20
End: 2009-05-12T16:50
Location: South Dakota

May 12, 2009 · NWS UNR · 14 events in 4 counties and zones

Severe thunderstorms developed across eastern Butte County and moved across northern Meade, southern Perkins, and Ziebach Counties. The storms produced hail as large as quarters and wind gusts to 65 mph and two tornadoes in Ziebach County.

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $100,000
Crop damage: None recorded
Events: 14

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS UNR wrote it up.

What forecasters said that day

The local office's own words before the first event, 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 first event at May 12, 12:28 PM MST, 2 hours 52 minutes earlier.

Area forecast discussion, May 12, 12:28 PM MST, 2 hours 52 minutes before

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
128 PM MDT TUE MAY 12 2009

.DISCUSSION...19Z SURFACE ANALYSIS HAD WEAK TROUGH FROM NORTH
CENTRAL SD INTO SOUTHEAST WY. PRESSURE FALLS BEGINNING IN EARNEST
ACROSS EASTERN WY/MT AS 110KT JET STREAM RACES INTO WY. SURFACE
LOW DEVELOPING OVER CENTRAL WY. THIS LOW WILL MOVE ALONG
APPROACHING COLD FRONT...CURRENTLY IN CENTRAL MT/WESTERN WY.
MOISTURE POOLING ALONG THE FRONT WILL CONTRIBUTE TO 0.5-1KJ/KG
MLCAPE. LONG DRAWN-OUT HODOGRAPH FORECAST WITH PLENTY OF SHEAR.
CAP CURRENTLY HOLDING THINGS BACK...BUT DO EXPECT AS UPPER SUPPORT
NEARS AND THERMAL RIDGE BREAKS DOWN...CONVECTION WILL DEVELOP THIS
AFTERNOON. SLIGHT RISK OF SEVERE THUNDERSTORMS WITH A FEW
DISCRETE CELLS NORTHEAST OF LOW AND SQUALL LONG ALONG COLD FRONT.
WIND AND HAIL MAIN THREATS. ACTIVITY WILL MOVE AWAY FROM THE CWA
LATER TONIGHT AS SURFACE LOW DEEPENS TO 988MB IN NORTHEASTERN ND.

WEDNESDAY...STRONG SURFACE TROUGH DEVELOPS WEST OF LOW INTO MT
LATE TONIGHT AND RUSHES INTO THE CWA WEDNESDAY MORNING. 900MB
GEOSTROPHIC WINDS NEAR 75KTS WITH 5-7MB/3HR PRESSURE RISES BEHIND
IT. 850-700MB WINDS LINED UP NICELY WITH 40-60KT WINDS. LOOKS LIKE
A CLASSIC HIGH WIND EVENT FOR NORTHWESTERN SD. WILL HOIST WARNINGS
AND ADVISORIES WITH AFTERNOON PACKAGE. BACKWASH MOISTURE WILL
LIKELY RESULT IN A FEW SHOWERS. CHILLY HIGHS WITH GOOD COLD AIR
ADVECTION.

WEDNESDAY NIGHT...SURFACE HIGH PRESSURE SETTLES OVER THE CWA
WITH CLEARING SKIES AND LITTLE WIND BY MORNING. WIDESPREAD
FROST/FREEZE POSSIBLE.

THURSDAY...WARM AIR ADVECTION BEGINS ANEW AS FLAT RIDGE MOVES OVER
THE NORTHERN PLAINS.

EXTENDED...COLD FRONT EXITS THE AREA EARLY FRIDAY WITH A FEW SHOWERS
AND THUNDERSTORMS EXPECTED IN CYCLONIC FLOW ALOFT. UPPER RIDGE
BUILDS OVER THE WESTERN CONUS FOR THE WEEKEND INTO EARLY NEXT
WEEK...BRINGING DRY CONDITIONS AND A WARMING TREND.

&&

.AVIATION...SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER THE AREA
THIS AFTERNOON AND EVENING. WINDS WILL BE VARIABLE AND GUSTY NEAR
THE THUNDERSTORMS...AND VIS MAY DROP TO IFR LEVELS IN HEAVER PRECIP.
CIGS OVER MOST LOCATIONS WILL REMAIN VFR...THOUGH SOME AREAS OF MVFR
CIGS WILL BE POSSIBLE TONIGHT OVER PARTS OF NORTHEAST WYOMING...THE
BLACK HILLS...AND NORTHWEST SOUTH DAKOTA. A VERY STRONG COLD FRONT
WILL MOVE THROUGH THE NORTHERN PLAINS OVERNIGHT INTO WEDNESDAY
MORNING...BRINGING VERY STRONG WEST TO NORTHWEST WINDS OF 30 TO 50
MPH WITH SOME HIGHER GUSTS FROM WEDNESDAY MORNING THROUGH WEDNESDAY
EVENING.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 6 AM MDT /7 AM CDT/ TO 6 PM MDT /7 PM CDT/
     WEDNESDAY FOR BENNETT-HERMOSA FOOT HILLS-JACKSON-MELLETTE-
     SHANNON-TODD-TRIPP.

     HIGH WIND WARNING FROM 6 AM TO 6 PM MDT WEDNESDAY FOR BUTTE-
     CUSTER CO PLAINS-HAAKON-HARDING-NORTHERN FOOT HILLS-
     NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID
     CITY-SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-
     ZIEBACH.

WY...HIGH WIND WARNING FROM 6 AM TO 6 PM MDT WEDNESDAY FOR
     NORTHEASTERN CROOK.

&&

HELGESON/RUDGE

Hazardous weather outlook, May 12, 1:30 PM MST, 1 hour 50 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
230 PM MDT TUE MAY 12 2009

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-131300-
BENNETT-BUTTE-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL RIVER-HAAKON-
HARDING-HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHEASTERN CROOK-
NORTHERN BLACK HILLS-NORTHERN CAMPBELL-NORTHERN FOOT HILLS-
NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY-
SHANNON-SOUTHERN BLACK HILLS-SOUTHERN CAMPBELL-SOUTHERN FOOT HILLS-
SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-
WESTERN CROOK-WESTON-WYOMING BLACK HILLS-ZIEBACH-
230 PM MDT (330 PM CDT) TUE MAY 12 2009

...HIGH WIND WARNING NORTHWESTERN SOUTH DAKOTA AND EXTREME
NORTHEASTERN WYOMING WEDNESDAY...
...WIND ADVISORY SOUTHERN SOUTH DAKOTA WEDNESDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND
NORTHEASTERN WYOMING.

.DAY ONE...TODAY AND TONIGHT

AN UPPER LEVEL DISTURBANCE AND COLD FRONT WILL MOVE THROUGH THE AREA
THIS AFTERNOON AND TONIGHT. THUNDERSTORMS WILL DEVELOP.

THERE IS A SLIGHT RISK THAT SOME OF THESE STORMS MAY BECOME SEVERE
THIS AFTERNOON AND EVENING OVER WESTERN AND CENTRAL SOUTH DAKOTA...
AND NORTHEAST WYOMING. LARGE HAIL AND DAMAGING WIND GUSTS WILL BE
THE MAIN THREATS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

BEHIND A SECONDARY COLD FRONT WEDNESDAY...A TIGHT PRESSURE GRADIENT
WILL PROMOTE VERY WINDY CONDITIONS. NORTHWEST WINDS WILL BLOW AT 25
TO 45 MPH WITH GUSTS TO 60 MPH. WINDS WILL QUICKLY DIMINISH WEDNESDAY
EVENING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

In the hours before

Special weather statement, May 12, 12:46 PM MST, 2 hours 34 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RAPID CITY SD
146 PM MDT TUE MAY 12 2009

WYZ054-056-057-071-122045-
NORTHEASTERN CROOK-NORTHERN CAMPBELL-WESTERN CROOK-
WYOMING BLACK HILLS-
INCLUDING THE CITIES OF...LIGHTNING FLAT AND ROCKYPOINT
146 PM MDT TUE MAY 12 2009

...STRONG THUNDERSTORM APPROACHING THE AREA...

AT 146 PM MDT...DOPPLER RADAR INDICATED A THUNDERSTORM WITH PENNY
SIZED HAIL AND FREQUENT CLOUD TO GROUND LIGHTNING. THIS STORM WAS
LOCATED 10 MILES WEST OF ROCKYPOINT...OR 35 MILES SOUTH OF BROADUS...
AND WAS MOVING EAST AT 30 MPH.

LOCATIONS IMPACTED INCLUDE...
  ROCKYPOINT...
  LIGHTNING FLAT...

HELGESON

Local storm report, May 12, 1:13 PM MST, 2 hours 7 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
213 PM MDT TUE MAY 12 2009

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

0155 PM     HAIL             8 NW ROCKYPOINT         44.99N 105.20W
05/12/2009  E0.88 INCH       CAMPBELL           WY   TRAINED SPOTTER

0200 PM     HAIL             4 N ROCKYPOINT          44.96N 105.10W
05/12/2009  E1.00 INCH       CAMPBELL           WY   PUBLIC

&&

MERICKSO

Local storm report, May 12, 1:26 PM MST, 1 hour 54 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
226 PM MDT TUE MAY 12 2009

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

0218 PM     HAIL             7 NNE ROCKYPOINT        44.99N 105.05W
05/12/2009  E1.00 INCH       CROOK              WY   CO-OP OBSERVER

            LASTED FROM 210 UNTIL 218

&&

MERICKSO

Special weather statement, May 12, 2:08 PM MST, 1 hour 12 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RAPID CITY SD
308 PM MDT TUE MAY 12 2009

SDZ001-012-122200-
BUTTE-HARDING-
INCLUDING THE CITIES OF...CASTLE ROCK...GUSTAVE AND REDIG
308 PM MDT TUE MAY 12 2009

...STRONG THUNDERSTORM APPROACHING THE AREA...

AT 305 PM MDT...DOPPLER RADAR INDICATED A THUNDERSTORM WITH NICKEL
SIZED HAIL...FREQUENT CLOUD TO GROUND LIGHTNING...AND STRONG WINDS.
THIS STORM WAS LOCATED 12 MILES SOUTH OF GUSTAVE...OR 33 MILES NORTH
OF DOWNTOWN BELLE FOURCHE...AND WAS MOVING EAST AT 35 MPH.

THE THUNDERSTORM WILL BE NEAR...
  REDIG AROUND 345 PM MDT...
  CASTLE ROCK AROUND 355 PM MDT...

A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR THE AREA UNTIL 10 PM
MDT.

RUDGE

Local storm report, May 12, 2:28 PM MST, 52 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
328 PM MDT TUE MAY 12 2009

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

0235 PM     HAIL             21 N HULETT             44.98N 104.60W
05/12/2009  E1.50 INCH       CROOK              WY   PUBLIC

&&

MERICKSO

Special weather statement, May 12, 3:05 PM MST, 15 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RAPID CITY SD
405 PM MDT TUE MAY 12 2009

SDZ001-002-012-013-122300-
BUTTE-HARDING-NORTHERN MEADE CO PLAINS-PERKINS-
INCLUDING THE CITIES OF...BISON...CASTLE ROCK...DATE AND FAIRPOINT
405 PM MDT TUE MAY 12 2009

...STRONG THUNDERSTORMS APPROACHING THE AREA...

AT 358 PM MDT...DOPPLER RADAR INDICATED A LINE OF THUNDERSTORMS WITH
NICKEL SIZED HAIL...WIND GUSTS TO 50 MPH...AND FREQUENT CLOUD TO
GROUND LIGHTNING. THESE STORMS WERE LOCATED FROM NEAR BUFFALO TO
CASTLE ROCK...MOVING EAST AT 45 MPH.

THE THUNDERSTORMS WILL BE NEAR...
  FAIRPOINT AROUND 415 PM MDT...
  ZEONA AND MUD BUTTE AROUND 420 PM MDT...
  STONEVILLE AROUND 425 PM MDT...
  SORUM...OPAL AND RED OWL AROUND 430 PM MDT...
  MAURINE AROUND 435 PM MDT...
  PRAIRIE CITY AROUND 440 PM MDT...

A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR THE AREA UNTIL 10 PM.

WETENKAMP

The radar

The Rapid City radar (KUDX), 95 km away, was scanning. The volume nearest the first event began at 22:21 UTC.

Open the radar archive at this moment

Event by event

7 thunderstorm wind, 5 hail, 2 tornado. Local standard time, as filed.

Hail, Butte

When: May 12, 3:20 PM MST
Where: Butte County, 15.28 mi SE of Hoover
Measured: 0.88 in hail
Reported by: Public
Coordinates: 44.962, -103.051

Thunderstorm Wind, Butte

When: May 12, 3:20 PM MST
Where: Butte County, 19.86 mi SE of Hoover
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 44.913, -102.988

None.

Hail, Meade

When: May 12, 3:35 PM MST
Where: Meade County, Mud Butte
Measured: 0.88 in hail
Reported by: Public
Coordinates: 45.000, -102.880

Thunderstorm Wind, Perkins

When: May 12, 3:45 PM MST
Where: Perkins County, 12.2 mi ESE of Zeona
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 45.145, -102.692

None.

Thunderstorm Wind, Meade

When: May 12, 3:50 PM MST
Where: Meade County, 5.32 mi WSW of Opal
Measured: 57 kt (66 mph) measured gust
Reported by: Public
Coordinates: 44.864, -102.576

Thunderstorm Wind, Perkins

When: May 12, 4:11 PM MST
Where: Perkins County, 16.36 mi SW of Usta
Measured: 52 kt (60 mph) estimated gust
Reported by: Trained Spotter
Coordinates: 45.043, -102.393

None.

Thunderstorm Wind, Meade

When: May 12, 4:15 PM MST
Where: Meade County, 5.27 mi E of Opal
Measured: 52 kt (60 mph) estimated gust
Reported by: Trained Spotter
Coordinates: 44.909, -102.373

None.

Thunderstorm Wind, Meade

When: May 12, 4:24 PM MST
Where: Meade County, (D07)faith Arpt
Measured: 54 kt (62 mph) measured gust
Reported by: ASOS
Coordinates: 45.030, -102.020

Hail, Ziebach

When: May 12, 4:25 PM MST
Where: Ziebach County, 10 mi WSW of Red Elm
Measured: 1 in hail
Reported by: Trained Spotter
Coordinates: 44.995, -101.959

Tornado, Ziebach

When: May 12, 4:28 PM MST
Where: Ziebach County, 7.45 mi W of Red Elm
Rating: EF0
Path length: 0.05 mi
Path width: 20 yd
Reported by: Storm Chaser
Coordinates: 45.070, -101.920

A storm chaser briefly observed a small tornado before rain obscured his view. Its location, length, and width were estimated. No damage was reported.

Tornado, Ziebach

When: May 12, 4:40 PM MST to 4:50 PM MST
Where: Ziebach County, 2.88 mi E of Red Elm to 2.29 mi NE of Dupree
Rating: EF1
Path length: 8.23 mi
Path width: 200 yd
Property damage: $100,000
Reported by: NWS Storm Survey
Coordinates: 45.051, -101.711

A tornado touched down west of Dupree and tracked eastward before dissipating northeast of Dupree. It dented several grain bins, blew over a small mobile home and semi trailer truck, tore sheet metal off sheds, and toppled a large communications tower.

Hail, Ziebach

When: May 12, 4:45 PM MST
Where: Ziebach County, 8 mi NW of Dupree
Measured: 1 in hail
Reported by: Public
Coordinates: 45.132, -101.696

Thunderstorm Wind, Ziebach

When: May 12, 4:45 PM MST
Where: Ziebach County, 8 mi NW of Dupree
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 45.132, -101.696

Hail, Ziebach

When: May 12, 4:50 PM MST
Where: Ziebach County, Dupree
Measured: 1 in hail
Reported by: COOP Observer
Coordinates: 45.050, -101.580

What these are

Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Tornado: A violently rotating column of air in contact with the ground and extending from a thunderstorm, filed with its path, width and Fujita or Enhanced Fujita rating from the damage survey.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in South Dakota in 2009 Every state in 2009 This day in weather history The tornado archive for South Dakota, 2009 Warnings in South Dakota, May 2009

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 163636, 163638, 163645, 163641, 163646, 163647, 163648, 163650, 163653, 175979, 175980, 163655, 163657, 163651.