A line of severe thunderstorms brought wind gusts to 70 mph across parts of southwestern South Dakota.
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.
A line of severe thunderstorms brought wind gusts to 70 mph across parts of southwestern South Dakota.
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 Aug 15, 1:04 PM MST, 2 hours 58 minutes earlier.
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 204 PM MDT SAT AUG 15 2009 .DISCUSSION...19Z SURFACE ANALYSIS HAS LOW PRESSURE OVER THE EASTERN DAKOTAS WITH COLD FRONT STRETCHING BACK THROUGH WESTERN NEBRASKA. TEMPERATURES RANGE FROM THE 50S AND 60S IN NORTHEAST WYOMING TO AROUND 80 ALONG THE SOUTHERN SOUTH DAKOTA BORDER. CLOUD COVER CONTINUES TO INCREASE FROM WEST TO EAST. UPPER LEVEL ANALYSIS HAS VIGOROUS LOW CENTER OVER SOUTHERN ALBERTA WITH STRONG SHORTWAVE EJECTING NORTHEAST THROUGH WYOMING ATTM. FOR LATE THIS AFTERNOON AND TONIGHT...SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE FROM WEST TO EAST AS POTENT SHORTWAVE IN SOUTH CENTRAL WYOMING LIFTS NORTHEAST. LINE OF STORMS IS ALREADY ORGANIZED ACROSS THIS AREA AND WILL BE MOVING INTO NORTHEAST WYOMING SHORTLY...AND INTO THE BLACK HILLS AREA WITHIN THE NEXT 3 HOURS. BOTH NAM AND GFS STILL PROG A WIDE SWATH OF PRECIP ACROSS THE AREA THIS EVENING. A FEW STORMS COULD BE STRONG TO SEVERE ACROSS FAR SOUTHERN PORTIONS OF SOUTH DAKOTA. OTHERWISE...RAIN SHOWERS AND ISOLATED THUNDER IS EXPECTED MOST OF THE NIGHT ACROSS THE REMAINDER OF THE AREA. UPPER LOW WILL BE NORTH OF THE REGION FOR SUNDAY AND MONDAY. DRIER WESTERLY FLOW WILL BE IN PLACE ACROSS THE AREA. A FEW SHOWERS OR STORMS ARE STILL POSSIBLE ON SUNDAY...MAINLY ACROSS NORTHERN PARTS OF THE AREA. TEMPS WILL BE MUCH COOLER THAN AVERAGE...WITH HIGHS MOSTLY IN THE 60S AND 70S. A FEW SHOWERS AND STORMS ARE POSSIBLE SUNDAY NIGHT AS WELL WITH ADDITIONAL WEAK ENERGY CROSSING THE AREA. MONDAY LOOKS MAINLY DRY WITH JUST A SLIGHT CHANCE OF AFTERNOON STORMS ACROSS SOUTHWEST SD. EXTENDED...NORTHWEST FLOW ALOFT OVER THE NRN PLAINS WILL CONTINUE THROUGH THE WEEK. A REINFORCING SHOT OF COOLER AIR WILL PENETRATE THE AREA ON WEDNESDAY AS A STRONG UPR WAVE IN THE NORTHWEST FLOW MOVES THRU. THIS SHOULD KEEP TEMPS BELOW NORMAL FOR MUCH OF THE WEEK...ALTHOUGH THERE IS SOME INDICATION THAT AN UPR RIDGE WILL BEGIN TO BUILD INTO THE NRN ROCKIES BY THE END OF THE WEEK. IF THIS HAPPENS...TEMPS WOULD RETURN TO NEAR AVERAGE READINGS TOWARDS THE END OF THE WEEK OR WEEKEND. THERE WILL ALSO BE PERIODIC CHANCES FOR PCPN THROUGH MIDWEEK. && .AVIATION...CDFNT CROSSING THE REGION WILL SPREAD MVFR AN LOCALIZED IFR CIGS ALONG WITH WDSPRD RAIN FROM WEST TO EAST TONIGHT. CONDITIONS WILL SLOWLY IMPROVE SUNDAY MRNG. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RAPID CITY SD 614 AM MDT SAT AUG 15 2009 SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058- 071-161300- 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- 614 AM MDT (714 AM CDT) SAT AUG 15 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND NORTHEASTERN WYOMING. .DAY ONE...TODAY AND TONIGHT SHOWERS AND THUNDERSTORMS ARE LIKELY TODAY AND TONIGHT...MAINLY DURING THE AFTERNOON AND EVENING HOURS...AS A STRONG COLD FRONT CROSSES THE AREA. THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS ACROSS MUCH OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA THIS AFTERNOON AND EVENING...MAINLY SOUTH AND EAST OF A LINE FROM PHILIP TO PINE RIDGE. LARGE HAIL AND STRONG WIND GUSTS WILL BE THE MAIN THREATS FROM ANY SEVERE STORMS. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY ISOLATED THUNDERSTORMS ARE POSSIBLE ACROSS PARTS OF NORTHEASTERN WYOMING AND FAR WESTERN SOUTH DAKOTA SUNDAY AFTERNOON AND NIGHT. SEVERE STORMS ARE NOT EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RAPID CITY SD 420 PM MDT SAT AUG 15 2009 SDZ027-041-152315- FALL RIVER-SOUTHERN FOOT HILLS- INCLUDING THE CITIES OF...ANGOSTURA RESERVOIR...ARDMORE... COLD BROOK RESERVOIR AND COTTONWOOD SPRINGS DAM 420 PM MDT SAT AUG 15 2009 ...STRONG THUNDERSTORMS APPROACHING THE AREA... AT 418 PM MDT...DOPPLER RADAR INDICATED A LINE OF THUNDERSTORMS WITH WIND GUSTS TO 50 MPH...AND FREQUENT CLOUD TO GROUND LIGHTNING. THESE STORMS WERE LOCATED ALONG A LINE EXTENDING FROM 7 MILES EAST OF EDGEMONT TO 11 MILES SOUTHEAST OF ARDMORE...AND WERE MOVING NORTHEAST AT 35 MPH. LOCATIONS IMPACTED INCLUDE... COTTONWOOD SPRINGS DAM... DOWNTOWN HOT SPRINGS AND ANGOSTURA RESERVOIR... MAVERICK JUNCTION AND COLD BROOK RESERVOIR... OELRICHS... ORAL AND SMITHWICK... A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR THE AREA UNTIL 800 PM MDT. JOHNSON
The national radar mosaic for the moment the first event began.
4 thunderstorm wind. Local standard time, as filed.
Large tree branches were broken off trees.
Wind gusts were estimated around 60 mph.
Wind gusts were estimated around 70 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2009Every state in 2009This day in weather historyWarnings in South Dakota, August 2009
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: 186290, 186296, 186297, 186298.