Scattered thunderstorms developed across north central Iowa along an elevated convergence zone in a near tropical atmosphere. Feed by a low level jet of 30 knots (about 35 mph), the thunderstorms evolved into a squall line that raced east southeast across eastern Iowa and northern Illinois.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. 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 DVN wrote it up.
Scattered thunderstorms developed across north central Iowa along an elevated convergence zone in a near tropical atmosphere. Feed by a low level jet of 30 knots (about 35 mph), the thunderstorms evolved into a squall line that raced east southeast across eastern Iowa and northern Illinois. Wind damage was the most common severe report with severe crop damage occurring across a large portion of Benton County, and to a lesser extent across Iowa, Linn, and Clinton Counties. The wind combined with a large amount of cloud to ground lightning resulted in power failures across parts of eastern Iowa and took two public safety communication towers off the air.
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 Quad Cities, IA wrote its last area forecast discussion before the first event at Aug 10, 2:32 AM CST, 1 hour 3 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 332 AM CDT THU AUG 10 2006 .DISCUSSION... MAIN FEATURE OF NOTE THIS MORNING IS STRONG MCS OVER NEB. RADAR AND SATELLITE TRENDS INDICATE MCS IS MAKING A RIGHT TURN AND MOVING MORE ENE OR E...AND LAST COUPLE OF SCANS INDICATE WEAKENING TREND. PERSISTENT AREA OF STRENGTHENING TSRA HAS MOVED ACROSS NRN IA THIS MORNING AS WELL...AND SMALLER CELLS WERE DEVELOPING ROUGHLY ALONG A LINE FROM DEWITT IA TO PRINCETON IL. RADAR TRENDS INDICATE THOSE AREAS OF CONVECTION MAY BE TRYING TO LINK INTO A BAND. SUBJECTIVE 12Z UPPER AIR ANALYSIS INDICATES WEAK WARM FRONT FEATURE EXTENDING ACROSS THE DAKOTAS/MN THROUGH WI. 850MB MOISTURE HAD POOLED OVER SRN MN/NRN IA. 500MB ANALYSIS INDICATED SERIES OF WEAK SHORTWAVES...INCLUDING ONE OVER IA/NWRN MO/KS...ONE IN THE CTRL DAKOTAS...AND TROUGH AXIS ACROSS MT/ID/UT...AS WELL AS AN UPPER RIDGE ACROSS MB/SASK/MT. UPPER-LEVEL JET RIGHT ENTRANCE REGION WAS DIRECTED TOWARD ERN NEB/WRN IA...WITH JET CURVING ACROSS MN/WI/MI/OH/PA. 07Z MSAS ANALYSIS INDICATES SURFACE LOW EXTENDS FROM ERN NEB SWWD TOWARD NWRN KS. SFC WARM FRONT WAS EVIDENT FROM ERN NEB TO NEAR KCNC TO KGBG TO KVYS...WITH VERY MOIST POOL OF DEWPOINTS IN THE MID 70S ACROSS IA/IL. PROFOUND LACK OF MODEL ABILITY TO DEPICT ONGOING CONVECTION THIS MORNING... AS STRONG MCS OVER NEB/WRN IA DOES NOT SHOW UP IN ANY OF THE MODELS. THIS OBVIOUSLY CREATES A LACK OF CONFIDENCE IN MODEL RESOLUTION OF THE NEXT 12-24 HR AND REALLY IN ALL OF THE RUNS. AS A RESULT...FORECAST IS LOW CONFIDENCE AND BASED MAINLY ON PATTERN RECOGNITION AND PERSISTENCE AS WELL AS BLEND OF MODEL SOLUTIONS. ELEVATED TSRA CURRENTLY DEVELOPING SHOULD PERSIST THROUGH MORNING...AND EXPECT MCS TO PERSIST THROUGH MORNING AS WELL...ENTERING THE CWA BY MID-MORNING. HAVE POPS IN THE LIKELY CATEGORY FOR MUCH OF THE CWA THIS MORNING...TAPERING TO CHANCES AS ACTIVITY FIZZLES AND MOVES EASTWARD DURING THE LATE MORNING/AFTERNOON. FAVORED LOCATION FOR CONVECTIVE DEVELOPMENT THIS AFTERNOON/EVENING DEPENDS STRONGLY ON LOCATION OF WARM FRONT...WHICH WILL HAVE A HARD TIME PROGRESSING NORTH INTO CLOUD DEBRIS. EXPECT IT TO LINGER ALONG THE IA/MO BORDER OR ACTUALLY SAG SOUTHWARD BACK INTO MO. LOWER CAPES N OF THE BOUNDARY WOULD LIMIT SEVERE POTENTIAL...WHILE AREAS ALONG AND SOUTH OF THE BOUNDARY SHOULD DEVELOP TSRA IN THE AFTERNOON AND EVENING. HAVE JUST CHANCE POPS SOUTH WITH THEORY THAT FRONT WILL BE SOUTH OF THE CWA. TEMPS TODAY ARE AGAIN TRICKY WITH POTENTIAL FOR CLOUDS TO MUDDY THE FORECAST...AND HAVE GONE TO LOW END OF GUIDANCE FOR TODAY. HAVE INCLUDED SLIGHT CHANCE OF PRECIP ON FRI AS SEVERAL RUNS OF THE NAM AND ECMWF HAVE INDICATED PRECIP AS A WAVE PASSES THROUGH THE GREAT LAKES AND RIGHT ENTRANCE REGION OF JET MOVES ACROSS CWA. WITH SO MUCH MOISTURE IN THE AIR...HARD TO LEAVE FORECAST DRY GIVEN THAT MUCH SUPPORT FOR PRECIP. DID KEEP SAT INTO SUN DRY AS HIGH SHOULD BE BETTTER ENTRENCHED IN THE CWA WITH DRY AIR ADVECTION SAT. RETURN FLOW KICKS IN AGAIN SUN AS HIGH PULLS EASTWARD...BUT NEXT FRONT IS STILL WELL UPSTREAM ON SUN. OVERALL...KEPT TEMPS CLOSE TO GUIDANCE AND KEPT PERSISTENCE OF FORECAST FROM LAST SEVERAL MORNINGS. MADE NO CHANGES TO DAYS 4-7. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && MAYES
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 506 AM CDT WED AUG 9 2006 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-101015- BUCHANAN-DELAWARE-DUBUQUE-BENTON-LINN-JONES-JACKSON-IOWA-JOHNSON- CEDAR-CLINTON-MUSCATINE-SCOTT-KEOKUK-WASHINGTON-LOUISA-JEFFERSON- HENRY IA-DES MOINES-VAN BUREN-LEE-JO DAVIESS-STEPHENSON-CARROLL- WHITESIDE-ROCK ISLAND-HENRY IL-BUREAU-PUTNAM-MERCER-HENDERSON- WARREN-HANCOCK-MCDONOUGH-SCOTLAND-CLARK- 506 AM CDT WED AUG 9 2006 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL ILLINOIS...NORTHWEST ILLINOIS...WEST CENTRAL ILLINOIS...EAST CENTRAL IOWA...NORTHEAST IOWA...SOUTHEAST IOWA AND NORTHEAST MISSOURI. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS WILL MOVE ACROSS THE AREA THIS MORNING...MAINLY NORTH OF HIGHWAY 34. THESE STORMS ARE NOT EXPECTED TO BECOME SEVERE...BUT THEY MAY PRODUCE LOCALLY HEAVY RAINFALL WITH SOME RAINFALL TOTALS UP TO TWO INCHES. SOME LOCATIONS MAY SEE PONDING IN ROADWAYS AND LOW-LYING AREAS...AS WELL AS RAPID RISES IN SMALLER STREAMS...WITH THIS RAIN. LATER THIS AFTERNOON...THUNDERSTORMS ARE EXPECTED TO DEVELOP IN WESTERN IOWA. THESE STORMS WILL ORGANIZE INTO A COMPLEX THAT MOVES ACROSS EASTERN IOWA...WESTERN ILLINOIS...AND NORTHEASTERN MISSOURI LATE THIS EVENING AND OVERNIGHT. THERE IS A SLIGHT RISK OF SEVERE WEATHER...MAINLY WEST OF A LINE FROM IOWA CITY TO GALESBURG. THE PRIMARY THREAT WOULD BE FROM DAMAGING WINDS...WITH LOCALLY HEAVY RAINFALL ALSO POSSIBLE. HEAVY RAINS COULD PRODUCE PONDING IN ROADWAYS AND LOW-LYING AREAS...AS WELL AS RAPID RISES IN SMALLER STREAMS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THUNDERSTORMS WILL BE POSSIBLE ACROSS THE AREA ON THURSDAY...AND THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS. THERE IS STILL UNCERTAINTY IN AREAS MOST AT RISK FOR SEVERE WEATHER...AS THE RISK DEPENDS ON THE LOCATION OF A WARM FRONT THAT IS EXPECTED TO BE ACROSS ILLINOIS...MISSOURI...AND IOWA. ISOLATED THUNDERSTORMS ARE POSSIBLE ON FRIDAY...BUT THESE STORMS ARE NOT EXPECTED TO BECOME SEVERE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY OR TONIGHT...BUT SPOTTERS ARE ENCOURAGED TO CONTACT THE NATIONAL WEATHER SERVICE OFFICE IN THE QUAD CITIES WITH REPORTS OF HEAVY RAINFALL...LOCALIZED FLOODING...HIGH WINDS AND WIND DAMAGE...OR OTHER SEVERE WEATHER. MAYES
The Quad Cities radar (KDVN), 134 km away, was scanning. The volume nearest the first event began at 09:39 UTC.
28 thunderstorm wind, 1 lightning, 1 heavy rain, 1 hail. Local standard time, as filed.
A probable lightning strike took down a tree in Vinton.
Severe straight line winds estimated around 61 knots (70 mph) began in the western part of the county southwest of Garrison and moved across the southern third to 40 percent of the county affecting about 160 square miles. According to official estimates, about 46,100 acres of corn was flattened with damage to about 5,100 acres of soybeans.
Numerous small to large trees were reported down across the town. Time estimated based on radar.
A measured gust of 62 knots (71 mph) with gusts to 57 knots (66 mph) when the spotter called in the report.
A hayrack was blown across a yard on its wheels.
Numerous branches were downed and trees snapped in half.
A public report of a two foot diameter healthy maple tree split in half. Sustained winds were estimated at 39 knots (45 mph) with multiple gusts to 57 knots (65 mph).
Several corn fields were flattened to the northwest and north of Amana in Lenox Township.
A spotter reported estimated winds of 52 to 61 knots (60 to 70 mph).
A spotter reported 1.20 inches of rain in 30 minutes. There were numerous reports of estimated and measured wind gusts of 39 to 43 knots (45 to 50 mph) as the storms moved through the metro area.
A spotter reported estimated 48 to 52 knot (55 to 60 mph) winds at the junction of U.S. 151 & highway 13.
Several corn fields were flattened to the west and south of Fairfax in Fairfax Township.
Law enforcement reported trees down along Avenue T (county highway 20).
KCRG TV reports penny to nickel size hail at the junction of Country Home Road & Lucore Road. Heavy rain was also reported with winds gusting to an estimated 39 knots (45 mph).
Sheriff department reported trees down near the intersection of Plotz Road NW & Falcon Avenue NW.
Sheriff department reported trees down along Scales Bend Road NE.
A utility company reported a tree blown down in town which destroyed a power pole.
The secondary roads department reported trees down in the town of Viola.
Sheriff department reported trees down near the intersection of Newport Road NE & Oak Ridge Trail NE.
A spotter reported a 12 inch diameter older tree down with numerous 4 inch plus diameter limbs down. Time estimated based on radar.
Sheriff department reported winds estimated at 52 to 61 knots (60 to 70 mph) with numerous trees down across the town.
Co-operative observer reported trees down and corn flattened on two farms southwest of town.
Co-operative observer reported 6 inch diameter limbs down with the power out along with 1.13 inches of rain.
Co-operative observer reported 3 foot diameter trees down and two power poles snapped south of his farm. A considerable amount of corn was flattened with damage to some buildings. Time estimated based on radar.
A large amount of corn was flattened from the Jackson/Clinton line to Delmar. The southern extent of the crop damage was highway 136 between Elwood and Delmar.
A spotter reported a 7 inch diameter walnut limb down and a 9 inch diameter oak limb down. Heavy rain of 1.10 inches was also reported.
A stopped semi was blown over near the junction of highway 136 & U.S. 61.
Several trees were reported down in the town.
A spotter reported estimated 48 to 52 knot (55 to 60 mph) winds.
City police reported trees down on the west side of town.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2006Every state in 2006This day in weather historyWarnings in Iowa, August 2006
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: 5528266, 5528265, 5528267, 5528269, 5528268, 5528271, 5528270, 5528272, 5528274, 5528277, 5528278, 5528273, 5528275, 5528276, 5528279, 5528333, 5528332, 5528334, 5528335, 5528337, 5528336, 5528338, 5528339, 5528340, 5528341, 5528342, 5528343, 5528344, 5528347, 5528345, 5528346.