Thunderstorms caused damaging winds and flash flood producing heavy rains in Dakota County in extreme northeast Nebraska from a little before to a little after midnight on August 24th and 25th.
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 caused damaging winds and flash flood producing heavy rains in Dakota County in extreme northeast Nebraska from a little before to a little after midnight on August 24th and 25th.
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 24, 8:24 PM CST, 2 hours 21 minutes earlier.
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 924 PM CDT MON AUG 24 2009 .DISCUSSION... CAP CONTINUES TO HOLD ACROSS NORTHERN PARTS OF THE AREA AND THIS LOOKS LIKE IT WILL HOLD AS BETTER UPPER LEVEL SUPPORT MOVES INTO NEBRASKA. SO...WITH THUNDERSTORM ACTIVITY FIRING UP OVER CENTRAL INTO NORTHEAST NEBRASKA THE ATTENTION TURNS TO THE SOUTHERN COUNTIES. THE NEW 0Z NAM WILL BE DISREGARDED AT THIS TIME AS IT SEEMS UNLIKELY THAT THE CONVECTIVE CLUSTER IN CENTRAL NEBRASKA WILL MOVE EAST-SOUTHEAST. SO...HAVE BUMPED UP POPS IN NE NEB AND NW IA AND INCREASED QPF AMOUNTS AS WELL. MAY NEED TO FURTHER BOLSTER QPF AMOUNTS AND ACTUALLY A LITTLE CONCERNED ABOUT SOME POTENTIAL FLASH FLOODING FROM ABOUT DIXON TO SIOUX CITY LATER TONIGHT. PWAT VALUES RUNNING ABOUT 2 INCHES AND WARM CLOUD DEPTH ABOUT 14-15 KFT. WITH 0.5 KM CAPE VALUES AROUND 3000 J/KG...UPDRAFTS WILL BE STRONG AND PRECIPITATION EFFICIENCY WILL BE VERY GOOD. SO...AN INCH OF RAIN IN 20 MINUTES A DEFINITE POSSIBILITY. /08 && .PREV DISCUSSION... BATCH OF ACCAS DEVELOPING NEAR KHON-KBKX AS LEADING SHORTWAVE LIFT LIFTS NORTHEAST ACROSS FORECAST AREA. AT THE SURFACE...WEAK PREFRONTAL TROUGH LOCATED ACROSS CENTRAL SOUTH DAKOTA. ATMOSPHERE REMAINS CAPPED HOWEVER SO AM NOT EXPECTING MUCH IN THE WAY OF CONVECTION OTHER THAT ELEVATED SHOWERS ACROSS FAR NORTHWESTERN CORNER THROUGH EARLY EVENING. MODELS SUGGESTING SHORT WAVE OVER PANHANDLE OF NEBRASKA WILL LIFT NORTHEAST...HOWEVER...DUE TO THE WEALTH OF HIGH CLOUDS ACROSS WESTERN NEBRASKA HAVE BEEN UNABLE TO IDENTIFY THIS FEATURE ON WATER VAPOR. SEVERE THREAT IS SOMEWHAT MARGINAL WITH WEAK SHEAR. FOR HAIL...50 DBZ CORE NEEDS TO APPROACH 40K. WITH ATMOSPHERIC SOUNDINGS FAIRLY WATER LOADED...SOME STORMS MAY BE ABLE TO PRODUCE SOME DECENT RAINFALL ACROSS THE AREA. FAVORED AREA FOR STORM DEVELOPMENT REMAINS ALONG AND WEST OF A LINE FROM TYNDALL TO BROOKINGS. AS COLD FRONT SHIFTS SOUTH AND EAST...IT BECOMES MORE WEST TO EAST ORIENTED POTENTIALLY KEEPING KSLB AND KSUX SOUTH OF THE FRONT. HAVE RAISED FORECAST LOWS WITH EXPECTED CLOUD COVER...BUT ESPECIALLY IN THESE AREAS ACROSS NORTHWEST IOWA. SHWRS AND TSTMS SHUD DCRS VERY SLWLY SWD TUE MRNG...BUT ANOTHER APPCHG SHRTWV FROM THE SW IN SPLIT FLOW SHUD CAUSE SOME INCRS AGN LATE TUE OR TUE EVE, BIG QSTN IS HOW EXTENSIVE AND HOW FAR N THIS RESURGENCE WILL BE. FOR NOW WILL ALLOW IT TO AFFECT MAINLY SERN PART OF FCST AREA MAINLY S AND E OF FSD...DCRS LATE TUE NGT WITH A SLGT CHC FAR SE WED MRNG. THIS IS AN INCRS OVER WHAT WE HAD ERYR AND WITH THE OSCILLATING NATURE OF MODEL SOLNS WILL NOT GO TOO WILD WITH THE TUE NGT/WED MRNG CHANGE...BUT IF EVE SOLNS COME IN AND KEEP THE RIPENING TREND...WE WUD HAVE TO MAKE TUE NGT WETTER OVER SRN FCST AREA AND EXTEND SOME PCPN FRTHR N. OTHER MODELS SUCH AS THE GFS AND ECMWF ARE WEAKER AND A LTL FRTHR S ON THIS LTL SYS. TEMPS WILL SHOW A SLOW COOLING TREND WITH CLOUD COVER TUE A FACTOR ESPLY S. LOW LEVEL COOLER AIR SHUD CONT TO FLOW INTO FCST AREA TUE THRU WED. EXPECT IN ANY EVENT FOR THE SHWRS/TSTMS TO BE GONE BY WED NOON...THO HAVE KEPT A SLGT CHC AFTN/EVE TSTMS IN OUR EXTRM SW WED. AS INSTBLTY INCREASES A LTL NEAR THAT AREA AND HALF DECENT HEATG EXPECTED. THU SHUD THEN BE DRY AND MILD WITH MID 70S EAST TO LOW 80S W. FIRST QSTN ON FRI THRU MON PERIOD IS CDFNT SLIPPING THRU THU/FRI AS UPPER LOW HEADS FOR A GREATLKS DIGGING. CLOSE CALL ON MENTIONING TSTMS OR NOT...ESPLY AS FAST AS SOME MODELS ARE NOR BRINGING IT THRU. WITH TIMING QSTNS HAVE LEFT OUT MENTN...SO THE ONLY PCPN MENTNION THIS FOUR DAY PD WILL BE A LSGT CHC SHWRS FAR E SAT ON BACK END OF COOL UPPER LOW. DESPITE THE COOL AIR THIS WILL BRING IN...GUIDNCE SEEMS A LTL TOO COOL ON HIGHS FOR THE PERIOD...FOR NOW JUST EDGED THEM UP A CPL DEGS. && .AVIATION... CONDS ARE EXPECTED TO BE PRIMARILY VFR THOUGH MAY SEE SOME BRIEF MVFR PERIODS THIS EVENING AS SCATTERED THUNDERSTORMS DEVELOP ALONG A COLD FRONT MOVING THROUGH THE AREA. BEST CHANCES FOR STORMS WILL BE ALONG AND NORTH OF HIGHWAY 60. FRONT WILL SLOW AS IT IS SHIFTING SOUTH AND BECOME MORE ORIENTED EAST WEST TOWARDS TUESDAY MORNING. MAY HAVE SOME MVFR CEILINGS JUST NORTH OF THE FRONT...WITH THE POTENTIAL FOR SHOWERS LINGERING INTO TUESDAY MAINLY ALONG AND SOUTH OF A LINE FROM YANKTON TO WINDOM. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && WILLIAMS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SIOUX FALLS SD 1135 AM CDT MON AUG 24 2009 SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098- IAZ001>003-012>014-020>022-031-032-NEZ013-014-251200- 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- 1135 AM CDT MON AUG 24 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA... SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS... THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG A COLD FRONT MOVING THROUGH THE REGION THIS EVENING. WHILE WIDESPREAD AND ORGANIZED SEVERE WEATHER IS NOT EXPECTED...AN ISOLATED THUNDERSTORM THIS EVENING FROM SOUTH CENTRAL SOUTH DAKOTA AND ACROSS AREAS NORTH OF INTERSTATE 90 MAY PRODUCE HAIL UP TO QUARTER SIZE AND WINDS UP TO 60 MPH. ADDITIONAL THUNDERSTORMS ARE LIKELY TO DEVELOP LATER TONIGHT FROM NORTHEAST NEBRASKA INTO NORTHWEST IOWA...BUT SEVERE STORMS ARE NOT EXPECTED. WIND AND FOG... PATCHY DENSE FOG OVER PORTIONS OF SOUTHWEST MINNESOTA AND NORTHWEST IOWA WILL SLOWLY DISSIPATE BY EARLY THIS AFTERNOON. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE THREAT FOR THUNDERSTORMS WILL GRADUALLY END AND SHIFT SOUTHWARD TUESDAY INTO TUESDAY NIGHT. SEVERE STORMS ARE NOT EXPECTED. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL BE POSSIBLE AFTER 7 PM CDT. && FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WWW.WEATHER.GOV/SIOUXFALLS. THIS INCLUDES THE GRAPHICAL HAZARDOUS WEATHER OUTLOOK. BT
The Omaha radar (KOAX), 127 km away, was scanning. The volume nearest the first event began at 04:47 UTC.
1 thunderstorm wind, 1 flash flood. Local standard time, as filed.
Thunderstorm winds caused tree damage. A large tree on the west side of the town of Jackson was blown down across a road, and trees up to 5 inches in diameter were broken off in the town.
Heavy rain caused flash flooding of streets in the towns of South Sioux City and Dakota City.
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: 194693, 194695.