An outflow boundary or gust front from a storm 30 to 40 miles west of the area produced some wind damage in Hiawatha, IA during the evening of May 11.
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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 DVN wrote it up.
An outflow boundary or gust front from a storm 30 to 40 miles west of the area produced some wind damage in Hiawatha, IA during the evening of May 11.
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 May 11, 6:06 PM CST, 2 hours 18 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 706 PM CDT WED MAY 11 2011 .UPDATE... THE MCS OVER SOUTH CENTRAL IOWA SHOULD CONTINUE TO MOVE EAST NORTHEAST THIS EVENING...ENCOUNTERING MORE STABLE AIR OVER THE NORTH SIDE OF THE COMPLEX WITH TIME. THIS SHOULD CONFINE THE STRONGEST STORMS TO ALONG AND SOUTH OF INTERSTATE 80 IN IOWA...AND EVENTUALLY...OVER ALL OF ILLINOIS. I HAVE INCREASED POPS THIS EVENING IN THE SOUTHWEST AS IT DOES APPEAR LIKELY TO BE IMPACTED OVER THE NEXT FEW HOURS. SHOULD THIS ACTIVITY INCREASE FURTHER AS THE LOW LEVEL JET INCREASES...A SIGNIFICANT INCREASE IN POPS AND QPF WOULD BE WARRANTED OVER A LARGE PORTION OF THE CWA FOR TONIGHT. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && ERVIN
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 956 AM CDT WED MAY 11 2011 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-121500- 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- 956 AM CDT WED MAY 11 2011 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 THE STORM PREDICTION CENTER HAS A SLIGHT RISK FOR SEVERE THUNDERSTORMS OVER THE ENTIRE OUTLOOK AREA FOR TODAY. LATE THIS MORNING...SCATTERED THUNDERSTORMS WILL BE POSSIBLE MAINLY WEST OF A LINE FROM BURLINGTON THROUGH CEDAR RAPIDS TO INDEPENDENCE. A COMPLEX OF THUNDERSTORMS IN SOUTH CENTRAL IOWA AND NORTH CENTRAL MISSOURI MAY MOVE INTO THIS AREA...BUT THE PRIMARY THREAT FROM THESE STORMS WILL BE SMALL HAIL AND LOCALLY HEAVY RAINFALL. THE GREATER RISK FOR SEVERE STORMS WILL BE LATER THIS AFTERNOON INTO EARLY EVENING AS ANOTHER COMPLEX OF THUNDERSTORMS MAY DEVELOP AND MOVE NORTH TO NORTHEAST ACROSS EASTERN IOWA AND NORTHWEST ILLINOIS. SOME OF THESE STORMS MAY BE CAPABLE OF PRODUCING HAIL GREATER THAN ONE INCH IN DIAMETER AND WIND GUSTS AROUND 60 MPH...ALONG WITH LOCALLY HEAVY RAINFALL. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THERE WILL BE SCATTERED TO NUMEROUS THUNDERSTORMS ON THURSDAY AS A STRONG STORM SYSTEM AND COLD FRONT TRACKS SLOWLY ACROSS THE MIDWEST. THE STORM PREDICTION CENTER HAS A SLIGHT RISK FOR SEVERE STORMS OVER MOST OF THE OUTLOOK AREA. THE MAIN THREATS APPEAR TO BE LARGE HAIL...FREQUENT LIGHTNING AND LOCALLY HEAVY RAIN. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON INTO EARLY EVENING. DLS
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
849 PM CDT WED MAY 11 2011
IAZ051-052-063-064-076>078-120245-
BENTON-IOWA-JOHNSON-KEOKUK-LINN-LOUISA-WASHINGTON-
849 PM CDT WED MAY 11 2011
...THUNDERSTORMS WITH GUSTY WINDS...
AT 844 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS WITH GUSTY WINDS ALONG A LINE EXTENDING FROM LADORA TO
SIGOURNEY...MOVING EAST AT 35 MPH.
* THUNDERSTORMS WILL BE NEAR...
WILLIAMSBURG...PARNELL AND CONROY AROUND 855 PM CDT...
KINROSS AROUND 900 PM CDT...
NORWAY AROUND 905 PM CDT...
WALFORD...WELLMAN AND AMANA AROUND 910 PM CDT...
OXFORD AROUND 915 PM CDT...
CEDAR RAPIDS MUNICIPAL AIRPORT AROUND 920 PM CDT...
WINDS GREATER THAN 35 MPH...ARE EXPECTED WITH THESE STORMS.
SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED.
LAT...LON 4211 9230 4218 9147 4168 9137 4118 9140
4124 9223
TIME...MOT...LOC 0148Z 269DEG 32KT 4183 9211 4133 9210
ERVINThe national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
A wind gust estimated to be 60 mph blew down some large tree branches in Hiawatha, IA around 924 pm CDT May 11.
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, May 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: 307281.