Lightning damaged a gas line and started a fire in a house in Flandreau during the predawn hours of May 10th.
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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.
Lightning damaged a gas line and started a fire in a house in Flandreau during the predawn hours of May 10th.
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 9, 7:20 PM CST, 6 hours 10 minutes earlier.
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 820 PM CDT MON MAY 9 2011 .DISCUSSION... STRONG WARM FRONTAL BOUNDARY EXTENDS ACROSS SOUTHERN COUNTY WARNING AREA THIS EVENING...WITH TEMPERATURES WELL INTO THE 90S THROUGH THE LOWER MISSOURI VALLEY. DRYLINE HAS PUNCHED ABOUT INTO THE SIOUX CITY AREA...WITH NARROW LOW LEVEL MOISTURE TRAJECTORY FROM IOWA INTO EASTERN AND THEN CENTRAL SD. LOW LEVEL EASTERLY JET LOCATED NORTH OF WARM FRONT...WITH SOME LATE AFTERNOON WINDS NEAR WIND ADVISORY CRITERIA...BUT NOW RELAXING A BIT AS DECOUPLING BEGINS. SO FAR...GREATEST DETAIL OF INTEREST THIS EVENING HAS BEEN WATCHING THE WARM FRONT ON RADAR. DURING THE AFTERNOON...BOUNDARY PUSHED RIGHT UP TO SIOUX FALLS...BUT WAS KNOCKED BACK BY DEEP EASTERLY FLOW OF COOLER AIR...WITH FINE LINE SEEN BACKING WESTWARD AND SOUTHWARD TO NEAR A MITCHELL TO BERESFORD LINE. BY EARLY EVENING... A WEAK CIRCULATION ALONG THE BOUNDARY WAS SEEN PROPOGATING WESTWARD...AND HAS SINCE PUSHED WARM FRONT BACK UP TO JUST SOUTH OF SIOUX FALLS...WITH MANY LOCATION SEEING TEMPERATURES CONTINUE TO RISE INTO EARLY EVENING NEAR THIS BOUNDARY. AS SURFACE WAVE CONTINUES TO MOVE FROM NEBRASKA INTO SD OVERNIGHT...WILL FIND WARM FRONT LIFTING NORTHWARD. DESPITE THIS...WEAKENING GRADIENT SOUTH OF BOUNDARY WILL ALLOW WITH DRY AIR FOR A DECENT TEMPERATURE FALL... SO TWEEKED A COUPLE OF DEGREES OFF THE EXPECTED LOWS. MAY GET REDEVELOPMENT OF SOME STRATUS IN AREAS NEAR AND NORTH OF THE WARM FRONT LATER IN NIGHT...WHICH WILL LIMIT THE FALL WHICH HAS ALREADY BROUGHT TEMPERATURES NEAR EXPECTED LOWS...WHICH MAY END UP A BIT NON DIURNAL...AND ONLY A BIT BELOW THE FORMER EXPECTATIONS. AS FAR AS THE CONVECTIVE THREAT...IT IS A VERY MINIMAL RISK TONIGHT. CERTAINLY WOULD NOT BE LOOKING FOR ANY POTENTIAL DEVELOPMENT...GIVEN THE DEGREE OF CAPPING TO EVEN ELEVATED PARCELS...AND WITH WAVE NEAR KOAX VEERING OFF TO THE NORTHEAST EARLY ON...ANY CONVERGENCE LEADING TO DEVELOPMENT WILL LIKELY BE OFF TO EAST OR NORTHEAST OF AREA. DID CUT OUT THE EVENING POPS...AND ONLY KEPT THE LATE NIGHT ACTIVITY TO COVER THE MINIMAL THREAT OF PROPAGATION OF WEAKENING STORMS INTO THE FAR WEST/NORTH. UPDATE PACKAGE ISSUED BY 0130Z. /CHAPMAN && .AVIATION... EXPECT MAINLY VFR CONDITIONS THROUGH 00Z WEDNESDAY. THE MAIN EXCEPTION WILL BE SOME AREAS NORTH OF THE WARM FRONT...NORTH OF INTERSTATE 90...WHERE SOME MVFR CEILINGS/VISIBILITIES WILL BE POSSIBLE AFTER 08Z TONIGHT INTO EARLY TOMORROW MORNING...BUT THIS AREA WILL LIKELY REMAIN NORTH OF KFSD. ADDED IN SOME LOW LEVEL WIND SHEAR FOR KFSD AND KSUX GIVEN THE STRONG INVERSION AND LOW LEVEL JET. A STRONG DIRECTIONAL SHEAR ENVIRONMENT NEAR WARM FRONTAL LOCATION BETWEEN KFSD AND KSUX...AND STRONGEST SPEED SHEAR FOR KSUX LOCATION AS LOW LEVEL WINDS WILL DECOUPLE MORE. /CHAPMAN && .PREV DISCUSSION... THE LBF AND OAX 12Z SOUNDINGS PRETTY MUCH TELL THE STORY FOR TONIGHT AS VERY DRY AND WELL CAPPED AIR EXISTS ACROSS THE REGION THIS AFTERNOON AND TONIGHT. THE SHEAR AND INSTABILITY ARE OBVIOUSLY SUPPORTIVE OF SEVERE THUNDERSTORMS...BUT NOT EXPECTING ANY DEVELOPMENT UNLESS SURFACE TEMPERATURES CAN CLIMB TO AROUND 100 DEGREES OR A LITTLE MORE. THE ONLY EXCEPTION SHOULD BE THE WESTERN EDGE OF THE CWA WHERE UPPER LEVEL TEMPERATURES ARE A LITTLE COOLER AND DEVELOPMENT IN CENTRAL SD COULD WORK EAST INTO THE AREA. CONFIDENCE NOT TOO HIGH ON THUNDERSTORMS AROUND THE CHAMBERLAIN AND HURON AREAS...BUT THOSE AREAS SHOULD HAVE THE BEST CHANCE OVERNIGHT. OTHERWISE VERY WARM AIR WILL SURGE NORTH OVERNIGHT AND PLAN ON INCREASING LOWS INTO THE MIDDLE TO UPPER 60S AS WINDS WILL REMAIN UP ALL NIGHT. /08 WARM FRONT CONTINUES TO SURGE NORTH ON TUESDAY. STRONG CAP IN PLACE WILL PREVENT ANY CONVECTION FROM FIRING. HAVE RAISED FORECAST HIGHS WITH THE EXPECTATION THAT THE FRONT WILL MOVE THROUGH FASTER THAN THE GFS AND NAM CURRENTLY INDICATE. EVEN WITH STOUT INVERSION IN PLACE...WENT WITH FORECAST HIGHS JUST SLIGHTLY BELOW 850 MB MIX OUT. HAVE FORECAST A RECORD HIGH IN SIOUX CITY (PREVIOUS RECORD IS 90)...AND A NEAR RECORD HIGH IN SIOUX FALLS (PREVIOUS RECORD IS ALSO 90). TEMPERATURES KINDA TRICKY ACROSS THE WESTERN EDGE OF THE FORECAST AREA AS COLD FRONT APPROACHES...BUT DO NOT ANTICIPATE MUCH OF AN IMPACT DURING THE DAY. COLD FRONT CREEPS EAST ON TUESDAY NIGHT INTO WEDNESDAY. AGAIN ATMOSPHERE REMAINS FAIRLY CAPPED...SO DRY CONDITIONS EXPECTED TO PREVAIL. MODELS INDICATE THE FRONT IS EXPECTED TO STALL BETWEEN THE I-29 AND HIGHWAY 60 CORRIDOR WHERE IT WILL REMAIN THROUGHOUT THE DAY ON WEDNESDAY. COULD SEE QUITE A TEMPERATURE CONTRAST WITH 850 HPA TEMPS VARYING FROM THE UPPER TEENS IN THE EAST...TO THE UPPER SINGLE DIGITS IN THE WEST. THIS WILL TRANSLATE TO HIGHS VARYING FROM THE MID 80S IN THE EAST...TO THE LOWER TO MID 60S IN THE WEST. FRONTAL PLACEMENT IS GOING TO BE CRITICAL IN TERMS OF TEMPERATURES IN THE MIDDLE...WHICH IS STILL SOMEWHAT UNCERTAIN. CAP BECOMES INCREASINGLY WEAK ACROSS NORTHWEST IOWA WITH THE BOUNDARY NEAR BY...AND MAY BE ABLE TO DEVELOP A FEW THUNDERSTORMS ACROSS NORTHWEST IOWA WEDNESDAY MORNING. AM NOT REALLY SEEING A STRONG TRIGGER OTHER THAN SURFACE BOUNDARY...SO KEPT POPS IN THE SLIGHT CHANCE TO CHANCE RANGE. CERTAINLY MUCH STRONGER FORCING WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT AS UPPER LEVEL LOW SHIFTS INTO THE REGION. HAVE RAISED POPS INTO THE CATEGORICAL RANGE WEDNESDAY NIGHT. STUBBORN UPPER LEVEL LOW IS SLOW TO MOVE OUT OF THE AREA POTENTIALLY CREATING ADDITIONAL SHOWERS AND THUNDERSTORMS THURSDAY INTO FRIDAY. COOL NORTHWEST FLOW EXPECTED THIS WEEKEND...WITH HIGHS 10-15 DEGREES BELOW NORMAL ON FRIDAY INTO SATURDAY. TEMPERATURES START TO MODERATE...ON SUNDAY INTO MONDAY...POTENTIALLY RETURNING CLOSER TO NORMAL EARLY NEXT WEEK. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SIOUX FALLS SD 114 PM CDT MON MAY 09 2011 SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098- IAZ001>003-012>014-020>022-031-032-NEZ013-014-101200- 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- 114 PM CDT MON MAY 09 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA... SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS... THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND OVERNIGHT IN EAST CENTRAL SOUTH DAKOTA...EXTENDING SOUTHWESTWARD INTO SOUTH CENTRAL SOUTH DAKOTA. CAPPING IS STRONG...THEREFORE THUNDERSTORM DEVELOPMENT IS CONDITIONAL ON THE CAP BREAKING. IF THE CAP DOES BREAK...THE MAIN THREAT WILL BE ISOLATED LARGE HAIL UP TO THE SIZE OF HALF DOLLARS OR GOLF BALLS. WIND AND FOG... SOUTHEAST WINDS WILL OCCASIONAL GUST AROUND 30 MPH TODAY ALONG AND EAST OF THE JAMES RIVER VALLEY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY AND WEDNESDAY EVENING IN NORTHWEST IOWA AND IMMEDIATE ADJACENT AREAS. THERE IS ALSO A THREAT FOR AREAS OF HEAVY RAINFALL WEDNESDAY NIGHT ACROSS THIS ENTIRE AREA. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL BE POSSIBLE FROM ABOUT 8 PM TO AROUND MIDNIGHT IN EAST CENTRAL SOUTH DAKOTA AND SOUTH CENTRAL SOUTH DAKOTA. && FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WWW.WEATHER.GOV/SIOUXFALLS. THIS INCLUDES THE GRAPHICAL HAZARDOUS WEATHER OUTLOOK.
The Sioux Falls radar (KFSD), 53 km away, was scanning. The volume nearest the first event began at 07:32 UTC.
1 lightning. Local standard time, as filed.
Lightning struck a light pole and damaged a gas line, starting a fire in a house. The fire destroyed a wall and siding.
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: 315483.