Thunderstorms with large hail moved across Kingsbury and Brookings Counties on the morning of May 8th.
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 FSD wrote it up.
Thunderstorms with large hail moved across Kingsbury and Brookings Counties on the morning of May 8th.
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 Sioux Falls, SD wrote its last area forecast discussion before the first event at May 8, 3:00 AM CST, 3 hours 40 minutes earlier.
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 400 AM CDT SUN MAY 8 2011 .DISCUSSION... CURRENT RADAR SHOWING SHOWERS BEGINNING TO DEVELOP ACROSS THE COUNTY WARNING AREA EARLY THIS MORNING WITH 850 TO 700 MB THETA E ADVECTION INCREASING ACROSS THE REGION. PRECIPITATION MAINLY IN THE FORM OF SHOWERS AT THIS POINT...THOUGH SEEING SOME LIGHTNING STRIKES BACK THROUGH CENTRAL NEBRASKA AND SOUTH CENTRAL SOUTH DAKOTA WHERE ELEVATED INSTABILITY AXIS EXISTS. EXPECT LOW TO MID LEVEL FORCING TO LIFT TO THE NORTH AND EAST THROUGH THE MORNING...WITH SHOWERS ENDING FROM SOUTHWEST TO NORTHEAST ACROSS OUR AREA INTO EARLY AFTERNOON. LOOKS TO BE A PRETTY WINDY DAY UNDER AN INCREASING GRADIENT WITH HIGH PRESSURE SITUATED OVER THE UPPER MIDWEST AND LOW PRESSURE INTENSIFYING OVER THE WEST CENTRAL HIGH PLAINS...ALONG WITH WINDS AT THE TOP OF THE MIXED LAYER PROGGED TO BE AROUND 35 TO 40 KTS. SHOULD SEE SOME SUN IN THE AFTERNOON ACROSS OUR SOUTH AND WEST WITH DEPARTING SHOWERS...AND WILL BE A WARM DAY WITH HIGHS AROUND 70 IN OUR NORTHEASTERN AREAS TO NEAR 80 THROUGH THE CHAMBERLAIN TO YANKTON TO SIOUX CITY CORRIDOR. WITH THE WARMING AND INCREASING LOW LEVEL MOISTURE...THE ATMOSPHERE WILL BECOME VERY UNSTABLE FROM CENTRAL SOUTH DAKOTA INTO EASTERN NEBRASKA BY LATE AFTERNOON AND EVENING WITH LI/S IN THE RANGE OF -6 TO -8 THROUGH OUR SOUTHWESTERN ZONES AND MUCAPE VALUES OF 2000 TO 2500 J/KG OVER THAT AREA. EFFECTIVE BULK SHEAR IS NOT OVERLY IMPRESSIVE...AROUND 22 KTS WITH THE BEST SHEAR BELOW 2 KM. IN ANY EVENT...SEVERE STORMS WOULD BE LIKELY IF THROUGH THAT AREA LATE THIS AFTERNOON AND EVENING IF WE CAN GET STORMS TO POP IN AN INCREASINGLY CAPPED ENVIRONMENT WITH THE APPROACH OF A MIDLEVEL SHORTWAVE IN A SOUTHWESTERLY UPPER LEVEL FLOW. THINK THE GREATEST THREAT WOULD BE LARGE HAIL AND DAMAGING WINDS...WITH TORNADO FORMATION LESS LIKELY WITH LCL/S OF AROUND 4300 FT IN OUR SOUTHWEST AND A SURFACE WARM FRONT REMAINING OVER SOUTHERN NEBRASKA. ONE CONCERN IS WHERE CONVECTION WILL TRACK IF IT DEVELOPS...WITH PRETTY BIG DIFFERENCES BETWEEN THE NAM...WHICH KEEPS MOST OF IT THROUGH THE MISSOURI RIVER CORRIDOR...AND THE ECMWF WHICH BRINGS THE CONVECTION MUCH FARTHER TO THE NORTH...THROUGH THE HEART OF OUR COUNTY WARNING AREA. STILL COULD SEE THE POSSIBILITY OF SEVERE STORMS...ALBEIT BECOMING ELEVATED...OVERNIGHT TONIGHT AS THE INSTABILITY EXPANDS OVER THE ENTIRE CWA. TONIGHT WILL BE A VERY MILD NIGHT WITH LOWS IN THE UPPER 50S TO LOWER 60S. THE SURFACE WARM FRONT APPROACHES OUR SOUTHERN ZONES ON MONDAY...THOUGH AGAIN THERE ARE MODEL DIFFERENCES ON HOW FAR NORTH THE FRONT GETS. AT THE SAME TIME...THE ATMOSPHERE BECOMES INCREASINGLY CAPPED WITH 750 MB TEMPS OF AROUND 13 TO 16 C ACROSS OUR AREA BY MONDAY AFTERNOON. THE QUESTION BECOMES CAN WE BREAK THE CAP IN OUR FAR NORTH AND WEST ON MONDAY AFTERNOON AND EVENING AS ANOTHER SHORTWAVE TRACKS JUST TO OUR NORTHWEST. THE ATMOSPHERE CONTINUES TO BE VERY UNSTABLE ON MONDAY...SO ANY CONVECTION THAT DEVELOPS WOULD MOST LIKELY BECOME SEVERE. MONDAY WILL BE AN EVEN WARMER DAY WITH HIGHS IN THE LOWER 70S NORTH LOWER 80S ALONG THE MISSIOURI RIVER. AFTER MONDAY...IT APPEARS THAT THERE WOULD BE LITTLE CHANCE OF CONVECTION ON TUESDAY WITH A STRONG CAP AND LITTLE IN THE WAY OF FORCING ACROSS THE AREA. TUESDAY LOOKS TO BE THE WARMEST DAY OF THE WEEK WITH HIGHS IN THE MID 70S NORTHWEST TO NEAR 90 IN OUR FAR NORTHWESTERN IOWA ZONES. NEXT CHANCE OF PRECIPITATION WILL MOST LIKELY COME LATER ON WEDNESDAY AS THE UPPER LEVEL TROUGH OVER THE WESTERN U.S. BEGINS TO LIFT INTO OUR AREA. /JM && .AVIATION... OVERALL...VFR CONDITIONS WILL LIKELY DOMINATE THIS AREA TODAY AND EARLY SUNDAY EVENING. THE MOST WIDESPREAD IMPACT TO GENERAL AVIATION OPERATIONS WILL BE THE INCREASING SOUTHEAST WINDS TODAY. FROM 17Z TO 01Z...FREQUENT GUSTS OF 25 TO 30 KNOTS ARE LIKELY TO OCCUR. CONCERNING PRECIPITATION...IN THE SHORTER TERM THERE MAY BE SOME ISOLATED TO SCATTERED HIGH BASED THUNDERSTORMS MOVING FROM WEST TO EAST ACROSS THE AREA THIS MORNING. BUT AGAIN DUE TO THE LIMITED MOISTURE AVAILABLE IN THE LOWER LEVELS...ANY SHOWER ACTIVITY SHOULD REMAIN IN THE VFR CATEGORY. MORE CONCERNING IS SUNDAY EVENING. A POTENT UPPER LEVEL DISTURBANCE IS FORECAST TO LIFT NORTHEASTWARD AND THE DEVIL IS IN THE DETAILS AS TO EXACTLY WHERE. THE ECMWF IS THE MOST BULLISH IN BRINGING HEAVIER TYPE RAIN AND THUNDERSTORMS IN THE SIOUX FALLS FORECAST AREA...WITH THE NAM ALSO BULLISH BUT A BIT FURTHER SOUTHWARD. THE ECMWF HAS BEEN VERY CONSISTENT IN THE PLACEMENT OF THIS WAVE THE PAST COUPLE OF DAYS...SO IT IS CONCERNING THAT SCATTERED THUNDERSTORMS OR MORE MAY OCCUR SUNDAY EVENING AND OVERNIGHT. THE BEST CHANCE FOR SEVERE WEATHER SUNDAY EVENING SO FAR APPEARS TO BE ALONG AND WEST OF THE JAMES RIVER VALLEY. /MJF && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SIOUX FALLS SD 539 AM CDT SUN MAY 08 2011 SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098- IAZ001>003-012>014-020>022-031-032-NEZ013-014-091200- AURORA-BEADLE-BON HOMME-BROOKINGS-BRULE-BUENA VISTA IA- CHARLES MIX-CHEROKEE IA-CLAY-CLAY IA-COTTONWOOD MN-DAKOTA NE- DAVISON-DICKINSON IA-DIXON NE-DOUGLAS-GREGORY-HANSON-HUTCHINSON- IDA IA-JACKSON MN-JERAULD-KINGSBURY-LAKE-LINCOLN-LINCOLN MN- LYON IA-LYON MN-MCCOOK-MINER-MINNEHAHA-MOODY-MURRAY MN-NOBLES MN- OBRIEN IA-OSCEOLA IA-PIPESTONE MN-PLYMOUTH IA-ROCK MN-SANBORN- SIOUX IA-TURNER-UNION-WOODBURY IA-YANKTON- 539 AM CDT SUN MAY 08 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA... SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS... THUNDERSTORMS WILL PUSH ACROSS PORTIONS OF THE AREA EARLY TODAY. WHILE A FEW OF THESE STORMS MAY PRODUCE SMALL HAIL...THEY ARE NOT EXPECTED TO BE SEVERE. BY LATE THIS AFTERNOON OR EVENING...THUNDERSTORMS MAY DEVELOP OVER SOUTH CENTRAL SOUTH DAKOTA AND SPREAD EASTWARD DURING THE NIGHT. THESE STORMS COULD PRODUCE HAIL TO THE SIZE OF HALF DOLLARS AND WINDS TO 60 MPH. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY THERE IS A CHANCE OF THUNDERSTORMS ACROSS THE AREA AGAIN ON MONDAY. WHILE THERE IS SOME UNCERTAINTY ON TIMING AND COVERAGE OF CONVECTION...THERE WILL BE THE POSSIBILITY OF SEVERE THUNDERSTORMS OVER SOUTH CENTRAL SOUTH DAKOTA THROUGH THE WESTERN JAMES RIVER VALLEY ON MONDAY EVENING. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL BE POSSIBLE AFTER 5 PM OVER SOUTH CENTRAL SOUTH DAKOTA...THEN IN AREAS FARTHER TO THE EAST DURING THE OVERNIGHT HOURS. && FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WWW.WEATHER.GOV/SIOUXFALLS. THIS INCLUDES THE GRAPHICAL HAZARDOUS WEATHER OUTLOOK.
The Sioux Falls radar (KFSD), 110 km away, was scanning. The volume nearest the first event began at 12:41 UTC.
4 hail. Local standard time, as filed.
Large hail, driven by less than severe winds, broke a few windows.
Nickel size hail whitened the ground.
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: 312164, 312165, 312166, 312167.