A thunderstorm produced damaging winds at Webb in Clay County on the early morning of July 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.
A thunderstorm produced damaging winds at Webb in Clay County on the early morning of July 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 Jul 10, 2:37 AM CST, 2 hours 58 minutes earlier.
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 337 AM CDT SUN JUL 10 2011 .DISCUSSION... A SMALL COMPLEX OF THUNDERSTORMS WILL WORK EAST THROUGH EAST CENTRAL SOUTH DAKOTA INTO SOUTHWEST MINNESOTA EARLY THIS MORNING. SOME SPOTTY HIGHER WINDS AND HEAVY RAIN WILL BE THE MAIN THREAT AS THIS PASSES. THE BETTER CHANCES WILL LIKELY BE BEFORE 12-14Z. AFTER THIS EXPECT A FAIRLY QUIET AND HUMID DAY. BY LATE AFTERNOON AND EVENING STILL PLANNING ON A WEAK IMPULSE TO MOVE FROM COLORADO INTO THE AREA...WHICH COULD SPARK SOME THUNDERSTORMS DURING THIS TIME. HOWEVER...AS MENTIONED IN THE PREVIOUS DISCUSSION...SOME CONCERN ABOUT WHAT WILL FIRE IN NORTHEAST KANSAS...EASTERN NEBRASKA AND WESTERN KANSAS WITH ENERGY THAT WRAPS TO THE NORTH AND A BETTER BOUNDARY. THIS WILL KEEP POPS IN THE CHANCES CATEGORY FOR THE MOST PART. WITH PWAT VALUES AROUND 1.80 INCHES AGAIN AND CAP VALUES LIKELY APPROACHING 3500 J/KG...HEAVY RAIN WILL BE A THREAT. ESPECIALLY WITH MARGINAL SHEAR PROFILES. ALTHOUGH THE LOW LEVEL JET DOES INCREASE A BIT EARLY THIS EVENING SO CANNOT RULE OUT ANOTHER MCS IN THE AREA WITH SOME SEVERE WEATHER. OTHERWISE A VERY WARM AND HUMID DAY WITH DEW POINTS IN THE LOWER TO MID 70S AND HIGHS FROM THE MID 80S TO POSSIBLY MID 90S. THIS WILL CREATE SOME HEAT INDICES AROUND 100 DEGREES THIS AFTERNOON. AND WITHOUT MUCH WIND IT WILL FEEL PRETTY UNCOMFORTABLE. THIS TIME AROUND...WHICH DOES HAVE SOME CONSISTENCY FROM YESTERDAY...THE MODELS ARE HINTING THAT MONDAY NIGHT INTO TUESDAY WILL BE THE HIGHEST THREAT FOR HEAVY RAIN AND SEVERE THUNDERSTORMS. A MARGINALLY BETTER WAVE EXPECTED TO MOVE ONTO THE PLAINS AND INCREASE LOW LEVEL WIND FIELD WHICH WILL AID IN PRODUCING BETTER SHEAR VALUES. WHEN COUPLED WITH FAIRLY STRONG INSTABILITY A POTENTIALLY MORE ORGANIZED SEVERE WEATHER THREAT WILL EXIST. STILL VERY HUMID BUT WITH ADDITIONAL CLOUD COVER MAY NOT BE QUITE AS HOT SO SHOOTING FOR MAINLY 80S FOR HIGHS ON MONDAY. TUESDAY HIGHS VERY DEPENDENT UPON CONVECTION BUT WILL CUT BACK A BIT WITH A LITTLE MORE CONFIDENCE IN CLOUDS AND THUNDERSTORMS. WILL AIM FOR HIGHS IN THE 70S TO LOWER 80S. && .AVIATION... && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. SD...NONE. &&
HAZARDOUS WEATHER OUTLOOK...CORRECTED NATIONAL WEATHER SERVICE SIOUX FALLS SD 430 AM CDT SUN JUL 10 2011 SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098- IAZ001>003-012>014-020>022-031-032-NEZ013-014-111200- 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- 430 AM CDT SUN JUL 10 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA... SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS... SCATTERED THUNDERSTORMS PRODUCING HEAVY RAINFALL OVER EAST CENTRAL SOUTH DAKOTA INTO SOUTHWEST MINNESOTA WILL GRADUALLY DISSIPATE THROUGH SUNRISE. SEVERE THUNDERSTORMS ARE NOT EXPECTED WITH THIS ACTIVITY. BY LATE AFTERNOON AND ESPECIALLY TONIGHT THUNDERSTORMS ARE EXPECTED TO DEVELOP WITH THE BEST CHANCE NORTH OF INTERSTATE 90. A FEW STORMS COULD PRODUCE WIND GUSTS TO 65 MPH AND HAIL TO THE SIZE OF HALF DOLLARS. FLOODING... A FEW OF THE THUNDERSTORMS THAT DEVELOP TONIGHT COULD PRODUCE HEAVY RAINFALL...ESPECIALLY NEAR HIGHWAY 14 INTO SOUTHWEST MINNESOTA. SOME LOCAL SPOTS COULD RECEIVE 2 TO 4 INCHES OF RAINFALL. RECORD HIGH RELEASES ALONG THE MISSOURI RIVER WILL CONTINUE INTO LATE SUMMER. HIGH WATER LEVELS WILL CAUSE SIGNIFICANT IMPACTS BETWEEN CHAMBERLAIN AND SIOUX CITY. ADDITIONALLY...THE JAMES RIVER WILL BE IN FLOOD UNTIL FURTHER NOTICE...ALONG WITH LOWER PORTIONS OF THE BIG SIOUX NEAR SIOUX CITY DUE TO BACKWATER EFFECTS FROM THE MISSOURI RIVER. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY ANOTHER ROUND OF THUNDERSTORMS WILL COME MONDAY NIGHT INTO TUESDAY MORNING. THE BETTER CHANCES APPEAR TO BE ACROSS CENTRAL AND FAR SOUTHEAST SOUTH DAKOTA WHERE HAIL TO THE SIZE OF HALF DOLLARS AND WIND GUSTS TO 70 MPH WILL BE POSSIBLE. HEAVY RAIN WILL ALSO BE A THREAT WITH AREAS AGAIN SEEING A POTENTIAL FOR 2 TO 4 INCHES OF RAINFALL. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL BE POSSIBLE AFTER 500 PM CDT. && 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
358 AM CDT SUN JUL 10 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0355 AM FLASH FLOOD CHESTER 43.89N 96.93W
07/10/2011 LAKE SD EMERGENCY MNGR
WATER WAS REPORTED OVER A FEW ROADS IN SOUTHEASTERN LAKE
COUNTY.
&&
KWEISSERThe Sioux Falls radar (KFSD), 156 km away, was scanning. The volume nearest the first event began at 11:34 UTC.
1 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds caused tree damage, including numerous branches up to 4 inches in diameter blown down.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2011Every state in 2011This day in weather historyWarnings in Iowa, July 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: 333716.