A cold front moved into northwest Iowa during the afternoon. The airmass was relatively unstable given a considerable amount of cloud debris was left over from the previous night.
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 DMX wrote it up.
A cold front moved into northwest Iowa during the afternoon. The airmass was relatively unstable given a considerable amount of cloud debris was left over from the previous night. Temperatures rose into the low to mid 80s, with dewpoint temperatures in the low 70s. CAPE values increased to 1500 to 3000 J/kg, with lifted indices in the -4 to -6 C range. There was weak convergence ahead of the cold front as a weak outflow boundary pushed southwest into the state. Precipitable water values increased to between 1.7 and 1.9 inches. The freezing level was quite high, around 14,500 feet with about 500 J/kg of CAPE available in the -10 to -30 C layer of the atmosphere. Downdraft CAPE was also around 500 J/kg. The atmosphere was weakly sheared with 20 to 30 kts of shear available during the early afternoon. This increased to 25 to 35 kts as the storms moved through. The LCL level was relatively low, around 750 meters. A narrow line of thunderstorms formed along the outflow boundary in southern Minnesota and dropped south into Iowa. A few of the storms intensified over Kossuth County and produced gusty winds and small hail. A MARC signature developed along the leading edge of the storms as they began to bow out. This produced high winds west of the Burt area. Telephone poles were blown down and damage was done to a building. The thunderstorms continued to move south along the instability axis. Winds of 60 to 70 MPH caused tree damage east of Fort Dodge in Webster County. At another nearby location, a hog confinement building was destroyed. Trees and a windmill also were blown over by the high winds. Strong winds continued as the system moved south. Winds around 70 MPH flattened corn fields south of Fort Dodge toward the Boone area.
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 Des Moines, IA wrote its last area forecast discussion before the first event at Jul 5, 11:08 AM CST, 3 hours 7 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 1208 PM CDT TUE JUL 5 2011 ...UPDATED 18Z AVIATION DISCUSSION... .UPDATE... MCS HAS NOT DISSIPATED AS ANTICIPATED AND IS NOW EXPECTED TO ENTER AT LEAST NWRN IA THIS MORNING SO HAVE BUMPED UP POPS TO THE BRINK OF LIKELIES. ALSO ADDED 12Z TAF DISCUSSION. && .SHORT TERM /TODAY/... IMMEDIATE QUESTION WILL BE PROGRESSION OF SD/MN MCS THIS MORNING. RADAR TRENDS SHOW COMPLEX HAS BEEN DISSIPATING AS IT MOVES SLOWLY SOUTH INTO LESS FAVORABLE INSTABILITY WITH UPSHEAR DEVELOPMENT STILL FOCUSING INTO SD WHERE HEAVY RAINS REMAIN IN PROGRESS. MEAN WIND ONLY 20KTS THERE SO FEEL THAT MCS WILL NOT MAKE IT INTO NRN IA UNTIL 15Z OR LONGER...IF AT ALL. ATTENTION THEN TURNS TO POTENTIAL FOR RE-DEVELOPMENT ALONG THE APPROACHING COLD FRONT DURING PEAK HEATING. NAM...GFS...AS WELL AS VARIOUS ARW/NMM WRFS HAVE LITTLE AGREEMENT ON HOW THIS MAY UNFOLD WITH VARIED SOLUTIONS IN TERMS OF LOW LEVEL CONVERGENCE PLACEMENT AND AVAILABLE INSTABILITY. THUS HAVE ENDED UP WITH A FAIRLY LOW CONFIDENCE BROAD BRUSH OF POPS ACROSS CENTRAL AND NRN IA. SRN MOST EXTENT APPEARS TO BE 00Z NCEP NMM WRF WHICH DEVELOPS CONVECTION AROUND KDSM 21Z-00Z SO HAVE LEFT THAT THE SRN EXTENT OF POPS TODAY. THERE IS A CONDITIONAL SEVERE WEATHER POTENTIAL WITH WEAK/MOD SHEAR AND INSTABILITY IN PLACE....DEPENDING ON MODEL SOLUTION. TEMPS ARE GENERALLY ON THE HIGH END OF GUIDANCE...AS SUGGESTED BY SOUNDINGS AND THEIR 24HR CHANGE VS PERSISTENCE. ONLY EXCEPTION WAS NW WHICH SHOULD BE COOLER EITHER DUE TO DEBRIS CLOUDS...LIGHT PRECIP OR ACTUAL FROPA. .LONG TERM /TONIGHT THROUGH SATURDAY/...MAIN CONCERN WITH THE EXTENDED PERIOD IS WITH THE POTENTIAL FOR SEVERE STORMS TONIGHT WITH COLD FROPA. OTHERWISE...GENERALLY DRY CONDITIONS THROUGH THE REMAINDER OF THE WORK WEEK. LEANED TOWARD A BLEND OF THE GFS/ECMWF FOR THE EXTENDED AND USED THE NAM TONIGHT INTO TOMORROW. OVERALL...MODELS LOOK TO BE IN DECENT AGREEMENT. TONIGHT THROUGH WEDNESDAY...STORMS LOOK TO CONTINUE THIS EVENING AHEAD OF THE COLD FRONT BUT SEVERE CHANCES DIMINISH WITH THE SUNSET AS INSTABILITY DECREASES. INSTABILITY IS REASONABLE WHERE SURFACE BASED AND 0-1KM BOTH RANGE IN THE 800-1500 J/KG. LOW LEVEL SHEAR VALUES ARE NOT IMPRESSIVE WHILE THE DEEP SHEAR SEEMS GOOD ENOUGH TO SUPPORT MORE ORGANIZED STORMS WITH THE POTENTIAL FOR DAMAGING WINDS/HAIL THREAT. NCAR AND NCEP WRF HAVE MCS CONTINUING INTO THE EVENING HOURS BUT ARE INCONSISTENT WITH INITIATION AND PLACEMENT. GENERALLY KEPT POPS ORIENTED FROM NORTHWEST TO SOUTHEAST WITH THE FROPA. THURSDAY THROUGH SATURDAY...UPPER RIDGE LOCATED OVER THE SOUTHERN PLAINS TO THE SOUTHWEST ALONG WITH SURFACE HIGH PRESSURE DOMINATING ACROSS THE MIDWEST WILL LEAD TO A GENERALLY DRY CONDITIONS THIS WEEK. WITH RIDGE PLACING FORECAST AREA WITHIN A WEAK NORTHWEST FLOW REGIME...THERE ARE A COUPLE RIPPLES OF SHORTWAVES DURING THE WEEK BUT LOOK TO REMAIN TO THE SOUTH OF IOWA. ONLY SLIGHT POPS ACROSS THE SOUTH ON THURSDAY TO REFLECT THIS TREND. NEXT BEST CHANCE WILL BE SATURDAY WITH AN UPPER LEVEL LOW AND COLD FRONT TO PUSH ACROSS THE STATE. && .AVIATION...05/18Z PRECIPITATION ACROSS NORTHWESTERN IOWA IS QUICKLY DISSIPATING AS EXPECTED...AND HAVE REMOVED MENTION FROM SITES. CLOUDS WILL LINGER THROUGH THE AFTERNOON...BUT CEILINGS WILL STAY VFR. COULD SEE ADDITIONAL DEVELOPMENT LATE INTO THE AFTERNOON NEAR 00Z...BUT AM UNCERTAIN AS TO TIMING AND LOCATION OF STORMS. HAVE TRENDED TOWARDS STORMS WITH CB MENTION. NEXT BIG CONCERN WILL BE WITH POSSIBLE FOG DEVELOPMENT AFTER 06Z. HAVE TRENDED VISIBILITIES LOWER...BUT WOULD EXPECT MOST LIKELY LOCATION FOR FOG/DENSE FOG TO BE AT NORTHERN SITES...KFOD...KMCW AND KALO. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...SMALL LONG TERM...PODRAZIK AVIATION...WILKINS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 502 AM CDT TUE JUL 5 2011 IAZ004-024-086-061015- EMMET-HUMBOLDT-WAPELLO- 502 AM CDT TUE JUL 5 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT FLOOD WARNINGS REMAIN IN EFFECT FOR PORTIONS OF THE DES MOINES RIVER BASIN. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. STRONG TO POTENTIALLY SEVERE THUNDERSTORMS ARE FORECAST THIS AFTERNOON AND TONIGHT ACROSS THE AREA. LARGE HAIL...DAMAGING WINDS...AND LOCALLY HEAVY RAIN ARE THE PRIMARY THREATS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY LINGERING THUNDERSTORMS ARE POSSIBLE OVER THE FAR SOUTH WEDNESDAY MORNING...BUT NO SEVERE WEATHER IS FORECAST AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING. IAZ005>007-015>017-023-025>028-033>039-044>050-057>062-070>075- 081>085-092>097-061015- KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-POCAHONTAS- WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN-WEBSTER-HAMILTON-HARDIN- GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE-BOONE-STORY-MARSHALL-TAMA- AUDUBON-GUTHRIE-DALLAS-POLK-JASPER-POWESHIEK-CASS-ADAIR-MADISON- WARREN-MARION-MAHASKA-ADAMS-UNION-CLARKE-LUCAS-MONROE-TAYLOR- RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS- 502 AM CDT TUE JUL 5 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT STRONG TO POTENTIALLY SEVERE THUNDERSTORMS ARE FORECAST THIS AFTERNOON AND TONIGHT ACROSS THE AREA. LARGE HAIL...DAMAGING WINDS...AND LOCALLY HEAVY RAIN ARE THE PRIMARY THREATS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY LINGERING THUNDERSTORMS ARE POSSIBLE OVER THE FAR SOUTH WEDNESDAY MORNING...BUT NO SEVERE WEATHER IS FORECAST AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED. KLP
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 1001 AM CDT TUE JUL 5 2011 IAZ033-034-051600- CALHOUN-SAC- 1001 AM CDT TUE JUL 5 2011 ...STRONG THUNDERSTORMS IN NORTHWEST IOWA... AT 957 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER EXTREME SOUTHEASTERN CHEROKEE COUNTY... MOVING SOUTHEAST AT 25 MPH. ONE HALF INCH DIAMETER HAIL...WINDS GREATER THAN 40 MPH...BRIEF MODERATE DOWNPOURS...ARE POSSIBLE WITH THIS STORM. * THE THUNDERSTORM WILL BE NEAR... SCHALLER BY 1015 AM CDT... NEMAHA AND EARLY BY 1035 AM CDT... SAC CITY BY 1055 AM CDT... LYTTON AND 9 MILES NORTHWEST OF YETTER BY 1100 AM CDT... GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW AROUND. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED. AW
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 148 PM CDT TUE JUL 5 2011 IAZ004>006-015-016-051945- EMMET-HANCOCK-KOSSUTH-PALO ALTO-WINNEBAGO- 148 PM CDT TUE JUL 5 2011 ...LINE OF STRONG STORMS TO IMPACT NORTHERN IOWA... AT 142 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM 17 MILES NORTH OF ESTHERVILLE TO 22 MILES NORTH OF ALGONA...MOVING SOUTHEAST AT 30 MPH. PENNY SIZE HAIL...WINDS GREATER THAN 40 MPH...BRIEF MODERATE DOWNPOURS...ARE POSSIBLE WITH THESE STORMS. LOCATIONS IMPACTED INCLUDE... SWEA CITY... DOLLIVER... BANCROFT... ARMSTRONG... TITONKA... ESTHERVILLE AIRPORT... ESTHERVILLE... WODEN... GRUVER... WALLINGFORD... BURT... WESLEY... RINGSTED... LONE ROCK... GRAETTINGER... GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW AROUND. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THESE STORMS HAVE PASSED. AW
The Des Moines radar (KDMX), 173 km away, was scanning. The volume nearest the first event began at 20:13 UTC.
11 thunderstorm wind, 3 hail. Local standard time, as filed.
Some 2 to 3 inch diameter branches down.
A listener reported telephone poles down, damage to a building, and possibly a trailer. Relayed by KLGA radio.
Power lines and trees down.
Maple tree blown down in front yard with limbs broken in half. Eight to ten inch diameter tree limbs down. Power was knocked out.
Tree limbs blown down by high winds. Rainfall of 1.5 inches in 30 minutes.
Large tree limbs down on the northeast side of Fort Dodge.
Hog building destroyed. Trees and a windmill down.
Large tree limbs and a half tree down at addresses 2128 to 2148 320th Street. Corn was partially flattened.
Green snap observed in farm fields.
Corn field flattened by wind gust.
Wind gusting 35 to 40 MPH as well.
One large 15 inch diameter tree limb blocking one lane of a highway. Several smaller 4 inch diameter limbs 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: 307493, 307291, 307491, 307494, 307495, 307293, 307294, 307441, 307308, 307752, 321953, 307307, 307439, 307440.