Thunderstorms produced heavy rain, which caused flash flooding of roads in Dixon County from just before to a little midnight on August 15th and 16th.
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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.
Thunderstorms produced heavy rain, which caused flash flooding of roads in Dixon County from just before to a little midnight on August 15th and 16th.
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 15, 7:55 PM CST, 3 hours 56 minutes earlier.
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 855 PM CDT SAT AUG 15 2009 .DISCUSSION... UPDATED EARLIER FOR WATCH ACRS WRN CWA. S/W LIFTING NEWD ACRS CWA AND ITS ASSOCD CDFNT WL CONT TO SPREAD TRW NEWD ACRS CWA OVERNIGHT. SVR THREAT NOT THAT GREAT XCP FOR A FEW SVR FAR WRN CWA LATE EVE WITH MAIN THREAT BEING WND. MAIN THREAT OVERNIGHT WL BE LOCALLY HVY RAINS. && .PREVIOUS DISCUSSION... TONIGHT...CURRENTLY MORE SCATTERED SHRA AND ISOLD TS IS REDEVELOPING THRU THE SRN AND ERN SECTIONS OF OUR FA. WAA AND ISENTROPIC LIFT CONTS TO BE ABUNDANT THIS EVENING...PROVIDING PLENTY OF BUOYANCY TO A VERY MOIST AIRMASS. WITH A FEW OF THE STRONGER CELLS...POCKETS OF HEAVY RAIN IS POSSIBLE THIS EVENING WITH HIGH PWATS...ESP ALONG AND E OF I 29. FOR NOW...DID NOT MENTION ANY ISOLD HEAVY RAIN IN THE GRIDS THIS EVENING WITH THOUGHTS THAT THE ACTIVITY WOULD BE MARGINAL ENOUGH TO PRECLUDE A MENTION. LATE TONIGHT...AN MCS SHOULD MOVE FM W TO E ACROSS THIS AREA. CURRENTLY ACTIVITY IS DEVELOPING IN ERN WY WITH THE MAIN CRUX OF THE S/W. THIS WAVE WILL THEN MARCH EWD TONIGHT. FOR NOW...PUT THE HIGHEST POPS THRU MOST OF THE SRN HALF OF OUR FA DUE TO THE BEST LLV JET CONVERGENCE IN THOSE AREAS. 40 TO 50 KTS IS FEEDING UP THRU ERN NEB AND KS TONIGHT...INTO ONLY 25 TO 35 KTS IN THE SRN HALF OF OUR FA. IN OUR NORTH...AROUND HURON TO BROOKINGS AND EVEN MARSHALL MN TO A DEGREE...THEIR LLV JET GETS SHEARED OFF A BIT FM THE SW. SO RAIN CHCS LOOK NOT TO BE AS GOOD IN THOSE AREAS. DYNAMICALLY...THE MID LVL SUPPORT PER THE H7-H5 QG FORCING NEARLY SPLITS THIS FA...WITH THE NRN STREAM ENERGY WELL NORTH OF THIS FA...AND THE MAIN PORTION OF THE SRN STREAM JUST SOUTH IN ERN NEB. BUT THE LLV JET INTERACTION GIVES MOST OF OUR SOUTH HALF CATEGORICAL POPS LATE TONIGHT WITH AREAS OF HEAVY RAIN CERTAINLY A THREAT. ALTERED OUR HUMID LOWS LITTLE TONIGHT...AS THE SFC CDFNT COMES IN TOO LATE TO REALLY BRING IN DRY AIR. /MJF COLD FRONT CURRENTLY PERCHED ACROSS WESTERN EDGE OF CWA PROGGED TO SHIFT EAST THROUGH FORECAST AREA SLIGHTLY FASTER THAN PREVIOUSLY EXPECTED. UPPER LEVEL WAVE SHIFTS OFF TO THE NORTHEAST SUNDAY MORNING WITH LOW LEVEL JET SHIFTING SOUTH AND EAST AHEAD OF APPROACHING TROUGH. WITH FORCING SPLITTING ACROSS EASTERN PORTIONS OF FORECAST AREA...HAVE ONLY UPPED POPS MINIMALLY ACROSS EAST CENTRAL PORTIONS OF FORECAST AREA. DRIER AIR FILTERING IN BEHIND THE FRONT WILL RESULT IN PARTIAL CLEARING...THOUGH CUMULUS SHOULD DEVELOP AND LINGER THROUGH EARLY EVENING. WITH CLEARING SLIGHTLY SOONER THAN EXPECTED...RAISED FORECAST HIGHS SLIGHTLY...BUT STILL KEPT TEMPERATURES SLIGHTLY COOLER IN THE EAST DUE TO SHORTENED DAYTIME HEATING. BATCH OF MID AND HIGH CLOUDS EXPECTED TO MOVE ACROSS THE AREA AS WEAK TRAIN OF MID LEVEL DISTURBANCES MOVE THROUGH. NOT MUCH IN THE WAY OF MOISTURE TO WORK WITH...THOUGH THERE IS SOME MARGINAL INSTABILITY THAT DEVELOPS THROUGHOUT THE DAY ACROSS FAR EASTERN EDGE OF FORECAST AREA. INSTABILITY IS FAIRLY MINIMAL...SO LEFT FORECAST DRY FOR NOW. HIGH PRESSURE WILL SHIFT EAST TUESDAY INTO WEDNESDAY AS SOUTH TO SOUTHWEST FLOW SETS UP ACROSS THE PLAINS. THE GULF IS WIDE OPEN...SO SHOULD SEE SOME NICE MOISTURE RETURN AHEAD OF WAVE MOVING IN FROM THE NORTH ON THE BACKSIDE OF UPPER LEVEL TROUGH. MODELS DEPICT BROAD WARM AIR ADVECTION ACROSS FORECAST AREA EARLY WEDNESDAY MORNING...WITH FOCUS ESPECIALLY ACROSS EASTERN EDGE OF FORECAST AREA. SOME QUESTIONS REMAIN ABOUT THE CAP...BUT LEFT SLIGHT CHANCE POPS IN THROUGH EARLY MORNING HOURS WEDNESDAY. MODELS CONTINUING TO WAFFLE ON HOW THEY HANDLE DEVELOPING UPPER LEVEL TROUGH HEADING LATE INTO THE WEEK. THE ECMWF SHOWED AN OPEN WAVE YESTERDAY WHILE THE GFS DEVELOPED A CLOSED LOW ACROSS THE NORTHERN PLAINS. WITH 00Z RUNS...GFS MAINTAINED THE CLOSED LOW...AND THE 00Z ECMWF ALSO DEVELOPED A CLOSED LOW OVER THE NORTHERN PLAINS. THE 06Z RUN OF THE GFS WAS MORE PROGRESSIVE THAN THE PREVIOUS RUNSS KEEPING THE UPPER LEVEL WAVE OPEN TILL IT WORKS INTO THE GREAT LAKES REGION...AN IDEA SUPPORTED BY THE 12Z RUN. THE ENSEMBLES ALSO SUPPORT FOLLOWING AN OPEN WAVE ACROSS THE NORTHERN PLAINS BEFORE BECOMING CUT OFF FURTHER EAST. FOR NOW...SIDED WITH THE IDEA OF AN OPEN WAVE ACROSS FORECAST AREA BUT TRENDED SLIGHTLY SLOWER WITH PROGRESSION OF WAVE...AND KEPT TEMPERATURES ON THE COOL SIDE OF CLIMATOLOGY. && .AVIATION... MVFR CONDS ARE STILL VERY MUCH A THREAT EAST OF THE JAMES RIVER VALLEY THIS EVENING. SCATTERED SHRA AND ISOLATED TS ALSO CONT TO REDEVELOP THRU THE AREA...AND WILL LIKELY LINGER THIS EVENING WITH ISOLATED AREAS OF HEAVY RAIN POSSIBLE. AN MCS IS CURRENTLY DEVELOPING ATTM IN ERN WY IN ASSOCIATION WITH THE NEXT VIGOROUS SHORT WAVE ENERGY. THIS ACTIVITY WL MOVE INTO OUR FORECAST AREA AFTER EVENING AND LATE TONIGHT...AND AT THIS TIME SHOULD AFFECT MAINLY THE SRN HALF OF OUR AREA ALONG AND SOUTH OF I 90. WITH THIS THUNDERSTORM COMPLEX...MVFR IS VERY LIKELY ALONG WITH BRIEF PERIODS OF IFR. AREAS OF MVFR STRATUS MAY LINGER SUNDAY MORNING UNTIL THE POST FRONTAL DRIER AIR ADVECTS IN BY SUNDAY AFTERNOON. /MJF && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE.
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SIOUX FALLS SD 1150 AM CDT SAT AUG 15 2009 SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098- IAZ001>003-012>014-020>022-031-032-NEZ013-014-161200- 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- 1150 AM CDT SAT AUG 15 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA... SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS... ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS COULD APPEAR THROUGH THE AFTERNOON AND EARLY EVENING HOURS...WITH ANY CONVECTIVE ACTIVITY NOT EXPECTED TO BE SEVERE DUE TO CLOUD INDUCED STABILITY. HOWEVER AFTER EVENING AND OVERNIGHT...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS BASICALLY ALONG AND WEST OF INTERSTATE 29...THROUGH EXTREME NORTHEAST NEBRASKA AND THE SOUTHEAST QUARTER OF SOUTH DAKOTA. THIS IS DUE TO A SURFACE COLD FRONT AND ASSOCIATED STRONG UPPER DISTURBANCE MOVING IN FROM THE WESTERN PLAINS. FLOODING... WITH THE CURRENT TRACK OF THE UPPER AIR DISTURBANCE EXPECTED TONIGHT...LOCALLY HEAVY RAINS OF 1 TO 2 INCHES WILL BE POSSIBLE MAINLY ALONG AND WEST OF A HURON TO SIOUX FALLS SOUTH DAKOTA...AND SIOUX CITY IOWA LINE AFTER EVENING AND LATE TONIGHT. THIS COULD CAUSE LOCALIZED FLOODING. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SHOWERS AND THUNDERSTORMS WILL PUSH FROM WEST TO EAST ACROSS THE AREA ON SUNDAY. THESE STORMS ARE NOT EXPECTED TO BE SEVERE...THOUGH THERE COULD BE LOCALLY HEAVY RAIN WITH THE STORMS...PRIMARILY THROUGH SOUTHWEST MINNESOTA AND NORTHWEST IOWA. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED THIS AFTERNOON...BUT COULD BE POSSIBLE WEST OF INTERSTATE 29 AFTER EVENING. && FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WWW.WEATHER.GOV/SIOUXFALLS. THIS INCLUDES THE GRAPHICAL HAZARDOUS WEATHER OUTLOOK.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
900 PM CDT SAT AUG 15 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0848 PM FLASH FLOOD 9 NE BURKE 43.28N 99.18W
08/15/2009 GREGORY SD LAW ENFORCEMENT
WATER RUNNING OVER ROAD 2 MILES EAST OF LUCAS.
&&
JCHAPMANThe Sioux Falls radar (KFSD), 126 km away, was scanning. The volume nearest the first event began at 05:52 UTC.
1 flash flood. Local standard time, as filed.
Heavy rain from thunderstorms caused flash flooding of a few roads, including U.S. Highway 20.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nebraska in 2009Every state in 2009This day in weather historyWarnings in Nebraska, 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: 194190.