Minor to moderate flooding occurred along the Belle Fourche River from the South Dakota-Wyoming state line downstream to the confluence of the Cheyenne River.
Every event with a place to put it. Tap one for its entry below.
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.
The episode as NWS UNR wrote it up.
Minor to moderate flooding occurred along the Belle Fourche River from the South Dakota-Wyoming state line downstream to the confluence of the Cheyenne River.
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 22, 2:15 AM MST, 7 hours 15 minutes earlier.
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 315 AM MDT SUN MAY 22 2011 .DISCUSSION...08Z ANALYSIS SHOWS BROAD SURFACE LOW OVER CENTRAL SOUTH DAKOTA WITH UPPER LOW NOW VERTICALLY STACKED OVER THE SFC LOW. REGIONAL RADAR MOSAIC SHOWS BANDS OF SHOWERS ROTATING AROUND THE LOW PRSSSURE SYSTEM WITH SOME LIGHT SHOWERS NOTED OVER NORTHEASTERN WYOMING AND HEAVIER SHOWERS OVER SOUTH CENTRAL MONTANA. THE LOW PRESSURE SYSTEM WILL CONTINUE TO MOVE VERY SLOWLY EASTWARD TODAY. AS IT DOES...THE WRAP AROUND PRECIPITATION OVER MONTANA WILL SHIFT EASTWARD INTO OUR FORECAST AREA. SHOWERS ARE AGAIN EXPECTED OVER MOST OF THE AREA TODAY WITH THE MOST PERSISTANT AREA OF RAINFALL EXPECTED OVER PARTS OF FAR NORTHEASTERN WYOMING...THE NORTHERN BLACK HILLS AND NORTHWESTERN SOUTH DAKOTA. RAINFALL AMOUNTS OF UP TO ONE HALF OF AN INCH WILL BE POSSIBLE ON THE PLAINS OF FAR NORTHEASTERN WYOMING AND NORTHEASTERN SOUTH DAKOTA WITH POSSIBLY AS MUCH AS AN INCH OR MORE OF RAIN IN THE FAVORED UPSLOPE AREAS OF THE BLACK HILLS. THE ADDITIONAL RAINFALL IS EXPECTED TO PROLONG THE FLOODING IN THOSE AREAS. THE SURFACE PRESSURE GRADIENT WILL TIGHTEN ON THE WEST SIDE OF THE LOW PRESSURE SYSTEM...CREATING SOME BREEZY/WINDY CONDITIONS TODAY. THE PRECIPITATION WILL GRADUALLY TAPER OF TONIGHT AS THE LOW PRESSURE SYSTEM CONTINUES TO MOVE OFF TO THE EAST AND WEAK UPPER RIDGE DEVELOPS. THE UPPER RIDGE WILL QUICKLY MOVE OFF TO THE EAST ON MONDAY MORNING AS SHORTWAVE ENERGY APPROACHES THE AREA AHEAD OF THE NEXT UPPER TROUGH. ABUNDANT LOW LEVEL MOISTURE OVER THE AREA WILL AID INSTABILITY FROM DIURNAL HEATING TO CREATE A CHANCE FOR MORE SHOWERS AND THUNDERSTORMS ON MONDAY AND MONDAY EVENING. THERE WILL BE ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS ON TUESDAY AS THE UPPER TROUGH BEGINS TO AFFECT THE AREA. EXTENDED...UPPER LOW WILL MOVE SOUTH AND EAST OF THE AREA ON WEDNESDAY. BEST CHANCES FOR SHOWERS WILL BE ACROSS SOUTHERN AND WESTERN PORTIONS OF THE CWA. ANOTHER UPPER LEVEL SYSTEM IS PROGGED TO MOVE EAST ACROSS THE NORTHERN PLAINS LATE THURSDAY INTO FRIDAY...BRINGING CHANCES FOR SHOWERS AND THUNDERSTORMS. AT THIS TIME...IT LOOKS LIKE A MAINLY DRY AND MILD HOLIDAY WEEKEND IS ON TAP AS UPPER LEVEL RIDGE BUILDS ACROSS THE ROCKIES. && .AVIATION...MVFR/IFR CONDITIONS WITH RAIN/RAIN SHOWERS CAN BE EXPECTED THIS MORNING INTO THE AFTERNOON...ESPECIALLY ACROSS NORTHEASTERN WY...THE BLACK HILLS AREA...AND NORTHWESTERN SD. CONDITIONS SHOULD BEGIN TO GRADUALLY IMPROVE FROM WEST TO EAST LATE THIS AFTERNOON AND TONIGHT AS UPPER LOW FINALLY MOVES AWAY FROM THE REGION. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RAPID CITY SD 429 AM MDT SUN MAY 22 2011 SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058- 071-231400- 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- 429 AM MDT (529 AM CDT) SUN MAY 22 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND NORTHEASTERN WYOMING. .DAY ONE...TODAY AND TONIGHT SCATTERED TO NUMEROUS RAIN SHOWERS AND ISOLATED THUNDERSTORMS WILL REDEVELOP ACROSS THE AREA TODAY. UP TO ONE HALF INCH OF RAINFALL IS POSSIBLE OVER FAR NORTHEASTERN WYOMING AND PARTS OF NORTHWESTERN SOUTH DAKOTA...WITH AN INCH OF RAIN POSSIBLE OVER THE FAVORED UPSLOPE AREAS OF THE NORTHERN BLACK HILLS TODAY. RAIN SHOWERS WILL GREATLY DIMINISH IN COVERAGE AND INTENSITY THIS EVENING. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS OVER PARTS OF THE AREA EACH DAY FROM MONDAY THROUGH FRIDAY. ALTHOUGH ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE...WIDESPREAD SEVERE WEATHER IS NOT EXPECTED. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
751 AM MDT SUN MAY 22 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0744 AM HEAVY RAIN 4 W NEW HAVEN 44.76N 104.93W
05/22/2011 M2.05 INCH CROOK WY TRAINED SPOTTER
0744 AM FLOOD 4 W NEW HAVEN 44.76N 104.93W
05/22/2011 CROOK WY TRAINED SPOTTER
LITTLE MISSOURI RIVER WELL OUT OF ITS BANKS. MANY FIELDS
FLOODED
0746 AM HEAVY RAIN 5 N HULETT 44.75N 104.61W
05/22/2011 M2.70 INCH CROOK WY TRAINED SPOTTER
0746 AM FLOOD 5 N HULETT 44.75N 104.61W
05/22/2011 CROOK WY TRAINED SPOTTER
MANY RANCH ROADS WASHED OUT
&&
MERICKSOPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
805 AM MDT SUN MAY 22 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0803 AM FLOOD HOOVER 45.11N 103.27W
05/22/2011 BUTTE SD CO-OP OBSERVER
SOUTH MOREAU RIVER WELL OUT OF ITS BANKS, ABOUT 1 MILE
ACROSS IN SOME LOWER AREAS, MANY FIELDS FLOODED AND AREA
ROADS IMPASSABLE
&&
MERICKSOThe national radar mosaic for the moment the first event began.
3 flood. Local standard time, as filed.
The river gage at the Wyoming-South Dakota state line crested at 16.3 feet, which is 1.3 feet above flood stage. Flood water covered several streets in Belle Fourche.
The river gage at the Highway 34 bridge east of Sturgis crested at 16.8 feet, 1.8 feet above flood stage.
The river gage north of Elm Springs crested at 16.0 feet, which is one foot above flood stage.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2011Every state in 2011This day in weather historyWarnings in South Dakota, May 2011
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: 313893, 313903, 313906.