A dry downdraft from dissipating thunderstorms produced damaging winds and a rapid rise in temperature from a few miles west of Sioux Falls to Sioux Falls during the predawn hours of August 3rd. At approximately 430 am the temperature rose from the lower 70s to near 100 degrees in a short period at the Sioux Falls airport.
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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.
A dry downdraft from dissipating thunderstorms produced damaging winds and a rapid rise in temperature from a few miles west of Sioux Falls to Sioux Falls during the predawn hours of August 3rd. At approximately 430 am the temperature rose from the lower 70s to near 100 degrees in a short period at the Sioux Falls airport. Wind gusts to 60 mph accompanied the rapid rise in temperatures.
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 Aug 2, 7:30 PM CST, 7 hours 45 minutes earlier.
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 830 PM CDT SAT AUG 2 2008 .DISCUSSION... ISOLATED ELEVATED SHOWERS AND THUNDERSTORMS HAVE GENERALLY FALLEN APART OR MOVED E OF THE FORECAST AREA THIS EVENING. STILL...THERE ARE CHANCES FOR THUNDERSTORMS THROUGH THE OVERNIGHT. ELEVATED WARM FRONT TO SHIFT NE TONIGHT AND LOW LEVEL JET TO STRENGTHEN...WHICH COULD POP A FEW THUNDERSTORMS OVER NW IA AND SW MN. BEST FORCING LOOKS TO BE LATE THIS EVENING IN THE AFOREMENTIONED AREAS...SO IF NOTHING POPS IN THE NEXT FEW HOURS...WILL LIKELY REMAIN DRY TONIGHT...WHICH IS BEGINNING TO APPEAR TO BE THE CASE BASED ON RADAR TRENDS. WILL BE MONITORING SFC BASED THUNDERSTORMS CURRENTLY NEAR PINE RIDGE. MID LEVEL FLOW SHOULD PUSH THIS CLUSTER OF STORMS ENE FOR THE NEXT FEW HOURS BEFORE TURNING MORE ERLY. ADDED SOME POPS TO THE SW CWA FOR LATER THIS EVENING AN INTO THE EARLY MORNING HOURS SHOULD STORMS HOLD TOGETHER...BUT MOST LIKELY STORMS WILL DIE OUT WITH THE LOSS OF DAYTIME HEATING AND STRENGTHENING CAP. && .AVIATION... MVFR TO VFR THOUGH THE EVENING HOURS ACROSS...HOWEVER AFTER MIDNIGHT CEILINGS ARE EXPECTED TO DROP TO IFR. ALSO MAY SEE SOME LIGHT FOG FORM LATE TONIGHT. FOG AND LOW CEILINGS WILL CLEAR OUT BY LATE SUN MORNING. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS TONIGHT AT ALL LOCAL TAF SITES...BUT PROBABILITIES ARE BELOW 30 PERCENT. && .PREV DISCUSSION... DVLPG SFC TROF FM WRN SD TO WRN NE WITH SFC WMFNT EXTENDING TO THE SW OF MO VLY...TRYING TO PIVOT NEWD INTO WRN AND SRN CWA THRU THIS EVE. LOTS OF INCOMING LOW LVL MOISTURE AND DSIPTG SC EAST OF FNT ATTM FM JAMES TO MISSOURI VALLEYS WITH SELY FLOW NOT CONDUCIVE TO MAX MIXING THIS AFTN. RATHER ISOLD ACCAS -TSRA NE OF KFSD AND IN NERN NE MOVG EWD WITH STEEP LAPSE RATES ABV 700 MB AND WARM ADVECTION. CAP UP THRU 700 MB WILL RULE THO AND SFC BASED CONVECTION NOT EXPCD WITH CONVECTIVE TEMPS OVER 100 DEG. HOWEVER...CANNOT RULE OUT SOME MORE WDLY SCT ACCAS RIDGE RIDERS REDVLPG IN NERN CWA TNGT...PSBLY BACKBUILDING INTO FAR NRN CWA LATE TNGT AS MORE SHORT WAVES MAKE DENT IN UPR RIDGE AND ASSCD CAP. PREV FCST TEMPS AND WINDS LOOK GOOD AS SELY FLOW AND INCRG DEWPOINTS HOLD UP LOWS. COULD SEE SOME LINGERING ELEVATED CONVECTION IN OUR FAR NORTH EARLY SUNDAY ALONG INSTABILITY/THETA E AXIS...OTHERWISE STRONG CAPPING SHOULD HINDER OUR CHANCES FOR THUNDERSTORM ACTIVITY ACROSS THE AREA FOR THE REMAINDER OF DAY. STILL LOOKING TO BE A HOT DAY WITH 850 MB TEMPS APPROACHING 30 DEGREES C IN OUR SOUTHWESTERN AREAS. ACTUALLY TRENDED TOWARD THE LESS HOT SIDE OF GUIDANCE WITH CONCERN THAT EASTERLY TO SOUTHEASTERLY WINDS WILL NOT BE OPTIMUM FOR BEST MIXING...IN ADDITION TO THE FACT THAT SOME HEATING MAY BE IMPEDED BY HIGH CLOUDS STREAMING ACROSS THE AREA. LOOKS TO BE A VERY UNCOMFORTABLE DAY...WITH DEWPOINTS INTO THE LOWER 70S...AND WHILE WE WILL BE FLIRTING WITH HEAT ADVISORY CRITERIA IN OUR SOUTHERN MOST ZONES...APPARENT TEMPERATURES SHOULD REMAIN JUST EITHER SIDE OF 100. BEGIN TO INCREASE POPS LATER ON SUNDAY NIGHT INTO MONDAY ALONG INSTABILITY/THETA E AXIS AS A DEVELOPING MID TO LOW LEVEL BOUNDARY SLIDES SOUTHWARD ACROSS THE AREA. STILL LOOKS TO BE A PRETTY WARM DAY WITH ONLY WEAK CAA...GENERALLY IN THE UPPER 80S TO LOWER 90S ACROSS THE CWA. WILL SEE BOUNDARY FINALLY DROP SOUTH OF THE AREA BY EARLY ON TUESDAY...AND TAPERED OFF POPS PRETTY EARLY IN THE DAY WITH FORCING EXITING OUR CWA A LITTLE EARLIER THAN IN PREVIOUS MODEL RUNS. BEHIND THE BOUNDARY...WILL FINALLY SEE MODERATING TEMPERATURES...IN FACT WILL BE SLIGHTLY BELOW SEASONAL NORMS ON TUESDAY AFTERNOON. IN THE EXTENDED...WED THRU SAT...WILL REMAIN PRIMARILY DRY...THOUGH COULD SEE A BIT OF PRECIPITATION ON WEDNESDAY NIGHT AS A SHORTWAVE DROPS THROUGH THE AREA. THERE WILL BE A SLIGHT COOLING TREND THROUGH THE PERIOD AS A STRONG UPPER LEVEL LOW OVER CENTRAL CANADA DROPS INTO THE GREAT LAKES REGION BY THE END OF THE WEEK...PULLING COOLER AIR INTO THE NORTH PLAINS AND UPPER MIDWEST FOR THURSDAY THROUGH SATURDAY. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && UPDATE...LIEBL RYRHOLM/JM
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SIOUX FALLS SD 1144 AM CDT SAT AUG 02 2008 SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098- IAZ001>003-012>014-020>022-031-032-NEZ013-014-031200- 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- 1144 AM CDT SAT AUG 02 2008 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA... SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS... ISOLATED SHOWERS OR A THUNDERSTORM MAY AFFECT AN AREA NORTH OF INTERSTATE 90 THIS AFTERNOON AND EARLY EVENING...BUT SHOULD NOT BE SEVERE. SCATTERED THUNDERSTORMS WILL DEVELOP AGAIN LATE EVENING ACROSS SOUTHWEST MINNESOTA AND TOWARD THE IOWA GREAT LAKES. AN ISOLATED STORM WILL BE CAPABLE OF PRODUCING LARGE HAIL UP TO HALF DOLLAR SIZE. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY THERE WILL BE A CHANCE FOR ADDITIONAL THUNDERSTORMS SUNDAY NIGHT ACROSS SOUTHWEST MINNESOTA. AGAIN...THERE WILL BE A THREAT FOR AN ISOLATED SEVERE STORM WITH LARGE HAIL AND DAMAGING WIND. MONDAY AFTERNOON AND EVENING WILL LIKELY FEATURE A MORE SIGNIFICANT COVERAGE OF THUNDERSTORMS FROM FAR SOUTHEAST SOUTH DAKOTA AND NORTHEAST NEBRASKA...THROUGH NORTHWEST IOWA. SEVERE STORMS WILL BE POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL BE POSSIBLE AFTER 10 PM FOR AREAS ACROSS SOUTHWEST MINNESOTA TOWARDS THE IOWA GREAT LAKES. && FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WWW.WEATHER.GOV/SIOUXFALLS. THIS INCLUDES THE GRAPHICAL HAZARDOUS WEATHER OUTLOOK.
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
Winds from a downdraft out of decayed thunderstorms caused tree damage, including trees up to 3 feet in diameter blown down, from Wall Lake to Sioux Falls. The winds also caused a rapid rise in temperature to near 100 degrees.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2008Every state in 2008This day in weather historyWarnings in South Dakota, August 2008
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: 130641.