A cold front moved southeast across the state during the evening of the 17th into the early morning of the 18th. The surface front reached southeast Iowa, however the upper level front lagged behind the surface front and remained over northern Iowa.
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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 DMX wrote it up.
A cold front moved southeast across the state during the evening of the 17th into the early morning of the 18th. The surface front reached southeast Iowa, however the upper level front lagged behind the surface front and remained over northern Iowa. The airmass was relatively unstable for mid September, with CAPE in the 2000 to 3000 J/kg range and lifted indices around -5 to -7 C. Precipitable water values were around 1.5 inches. The effective wind shear was in the 30 to 40 kt range. Thunderstorms formed on the elevated front. Clearly, the storms were elevated in nature and produced little wind as they passed. Many of the storms produced small hail. One of the stronger storms over Sac County produced penny to nickel size hail near the town of Early. The thunderstorms continued to develop during the day. Nickel size hail fell southwest of Dow City in Crawford County during the late morning hours.
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 Sep 18, 2:13 AM CST, 6 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 313 AM CDT SAT SEP 18 2010 .SHORT TERM /TODAY/... CDFNT MAKING SLOW PROGRESS SWD. SHOULD SEE THE SFC FNT MOVE SOUTH OF THE CWA...HWVR THE H8 FRONT STRUGGLED TO GET ANY FARTHER SOUTH THAN I-80. WILL KEEP POPS GOING THRUT THE DAY OVR MOST OF THE CWA FOR ELEVATED CONVECTION. STRONGEST FORCING WILL BE ERY THIS MRNG WITH A DOWNWARD TREND THRU MUCH OF THE DAY. NOT LKLY TO SEE ANYTHING ALL THAT SIG TDA WITH FRONTOGENESIS REGION SHFTG TO THE EAST BY THIS AFTN. TEMPS A LITTLE PROBLEMATIC WITH LITTLE OR NO RISE LIKELY OVR THE SERN ZNS WHERE CDFNT HASN'T PASSED. WILL SEE SOME RECOVERY ELSE...BUT CLOUDS WILL KEP TEMPS WELL BLO NORMAL WITH 55-60 ABOUT DOING IT FOR HIGHS OVR THE N HLF OF THE STATE. .LONG TERM /TONIGHT THROUGH FRIDAY/... FAIRLY WET FORECAST APPEARS ON TAP WITH SEVERAL SYSTEMS LIKELY TO PRODUCE RAINFALL ACROSS THE CWA THIS WEEKEND AND NEXT WEEK. THE FRONTAL SYSTEM STALLED OVER THE AREA TODAY WILL LINGER WITH LITTLE IF ANY MOVEMENT TONIGHT...AS SUBTLE SHORTWAVES PASSING OVERHEAD IN NEARLY ZONAL 500 MB FLOW WILL ACTIVATE ADDITIONAL SHOWERS AND STORMS ACROSS THE AREA. IN OUR NORTHERN AND NORTHWESTERN COUNTIES POPS WILL BE MITIGATED SOMEWHAT BY RELATIVELY DRIER AIR OUT OF A SURFACE HIGH MOVING ACROSS MN. AS A BRIEF PERIOD OF MID-LEVEL RIDGING ENSUES ON SUNDAY THE FRONTAL BOUNDARY WILL BE PUSHED BACK NORTHWARD AS A WARM FRONT...EXITING OUR CWA TO THE NORTH SOMETIME SUNDAY EVENING/NIGHT AND BRINGING A BRIEF END TO POPS EARLY NEXT WEEK. BY MONDAY A DEEP LAYER TROUGH WILL BE DIGGING INTO THE NORTHERN ROCKIES RESULTING IN AN AMPLIFIED PATTERN ACROSS THE MIDWEST. AS THE CORRESPONDING 500 MB FLOW BEGINS TO TURN MORE SOUTHWESTERLY ON MONDAY AFTERNOON WAA WILL BE ENHANCED ALONG WITH STEADY MOISTURE ADVECTION IN SOUTHERLY LOW-LEVEL FLOW LEADING TO A WARM AND HUMID DAY. THE AFOREMENTIONED TROUGH WILL THEN EJECT EASTWARD ACROSS THE UPPER U.S. AS A SERIES OF SHORTWAVE IMPULSES...WITH THE LEADING IMPULSE EXPECTED TO TRAVERSE OUR AREA MONDAY NIGHT/TUESDAY AND THE SECOND AROUND THURSDAY OR THURSDAY NIGHT. THE FIRST OF THESE WILL BRING A COLD FRONT ACROSS THE CWA ENTERING OUR NORTHWESTERN COUNTIES LATE MONDAY NIGHT AND REACHING OUR SOUTHEAST BY TUESDAY EVENING. GIVEN THE MOIST AIRMASS IN PLACE AHEAD OF THIS FRONT AND FORCING PROVIDED BY THE SHORTWAVE ALOFT WE SHOULD HAVE NO PROBLEM GENERATING THUNDERSTORMS...ALTHOUGH INSTANTANEOUS COVERAGE IS SOMEWHAT MORE DIFFICULT TO PREDICT. HAVE INDICATED AN INCREASING TREND IN POPS UP TO THE TOP OF CHANCE RANGE ON TUESDAY AND TAPERED THEM TO THE SOUTHEAST TUESDAY NIGHT AS THERE IS GOOD CONSENSUS AMONG THE MODELS THAT THE BOUNDARY WILL BE FAIRLY PROGRESSIVE ACROSS MUCH OF THE AREA. THIS WILL ALSO MITIGATE FLOODING CONCERNS ALTHOUGH LOCALLY HEAVY RAIN WILL BE POSSIBLE WITH GOOD MOISTURE TRANSPORT AND HIGH PWATS FOR THIS TIME OF YEAR. AS THE NEXT IMPULSE APPROACHES WEDNESDAY NIGHT THE FRONTAL BOUNDARY WILL ONCE AGAIN MOVE NORTHWARD AS A WARM FRONT...SIMILAR TO THE EARLIER SYSTEM THIS WILL LEAD TO WAA REGIME STORM DEVELOPMENT AND ANOTHER PERIOD OF POPS PERSISTING UNTIL A SOMEWHAT STRONGER COLD FRONT SWEEPS ACROSS THE AREA LATE THURSDAY OR THURSDAY NIGHT. THIS WILL RESULT IN DRIER AND COOLER WEATHER TO END THE WORK WEEK. && .AVIATION... 18/06Z...FRONTAL BOUNDARY HAS MOVED INTO SOUTH CNTRL IA AND WILL CONTINUE TO SINK SLOWLY S OVERNIGHT AND BE NEAR THE IA/MO BORDER BY 12Z. WARM ADVECTION OVER THE SFC BOUNDARY WILL CONTINUE TO INITIATE SHOWERS AND THUNDERSTORMS OVER THE AREA TONIGHT AND INTO SAT MORNING. POTENTIAL RETURN TO VFR CONDITIONS OVER NORTH SITES BY THE AFTERNOON. EXPECT DRIZZLE OR SHOWERS TO LINGER THROUGH THE PERIOD WITH MVFR OR LOWER CIGS IN PLACE. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...MS SEP 10 LONG TERM...LEE AVIATION...DONAVON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 1118 PM CDT FRI SEP 17 2010 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097-181100- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT-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-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE- DAVIS- 1118 PM CDT FRI SEP 17 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TONIGHT SCATTERED THUNDERSTORMS ARE EXPECTED TONIGHT. SOME MAY BE SEVERE SOUTH OF U.S. HIGHWAY 30 AND WEST OF INTERSTATE 35 WITH HAIL UP TO AN INCH IN DIAMETER. MODERATE RAINFALL IS EXPECTED TONIGHT SOUTH OF HIGHWAY 20 WITH LOCAL RAINFALL AMOUNTS OF UP TO TWO INCHES POSSIBLE. SOME PONDING OF WATER MAY OCCUR WITH THE HEAVIER STORMS. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY ISOLATED TO SCATTERED THUNDERSTORMS ARE IN THE FORECAST THROUGH SUNDAY NIGHT. A FEW MAY PRODUCE LOCALLY HEAVY RAIN WITH THE POTENTIAL FOR SOME FLOODING IF REPEATED RAINS OCCUR OVER SIMILAR AREAS. A FEW STORMS MAY ALSO BE SEVERE SATURDAY NIGHT SOUTH OF INTERSTATE 80. ADDITIONAL THUNDERSTORM CHANCES ARE IN THE FORECAST MONDAY NORTH... AND AREA WIDE TUESDAY THROUGH THURSDAY. THE SEVERE WEATHER AND HEAVY RAIN POTENTIAL IN THIS PERIOD WILL BE BETTER DETERMINED IN THE COMING DAYS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED BRIEFLY TONIGHT AND AGAIN SATURDAY NIGHT ACROSS THE SOUTH.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 256 AM CDT SAT SEP 18 2010 IAZ033-180830- SAC- 256 AM CDT SAT SEP 18 2010 ...THUNDERSTORMS WITH HAIL APPROACHING... AT 254 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER EAST CENTRAL IDA COUNTY...MOVING EAST AT 30 MPH. PENNY SIZE HAIL...BRIEF HEAVY DOWNPOURS...ARE POSSIBLE WITH THIS STORM. * THE THUNDERSTORM WILL BE NEAR... SCHALLER AND 7 MILES NORTH OF ODEBOLT BY 305 AM CDT... EARLY BY 315 AM CDT... NEMAHA AND 9 MILES NORTH OF LAKE VIEW BY 325 AM CDT... SAC CITY BY 330 AM CDT... SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED.
The Des Moines radar (KDMX), 144 km away, was scanning. The volume nearest the first event began at 08:17 UTC.
2 hail. Local standard time, as filed.
Trained spotter in Early reports a few minutes of dime to nickel size hail.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2010Every state in 2010This day in weather historyWarnings in Iowa, September 2010
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: 250962, 251230.