A warm front remained nearly stationary across northern Iowa and northern Illinois during the afternoon hours of May 11th. Severe thunderstorms developed along and north of the warm front and produced large hail across parts of western Wisconsin.
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 ARX wrote it up.
A warm front remained nearly stationary across northern Iowa and northern Illinois during the afternoon hours of May 11th. Severe thunderstorms developed along and north of the warm front and produced large hail across parts of western Wisconsin. Law enforcement estimated golf ball size hail near Tomah (Monroe County) which damaged police cars.
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 La Crosse, WI wrote its last area forecast discussion before the first event at May 11, 9:59 AM CST, 3 hours 2 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1059 AM CDT WED MAY 11 2011 .UPDATE... FIRST WAVE OF SHOWERS AND THUNDERSTORMS MOVING ACROSS MINNESOTA AND WESTERN WISCONSIN...THAT HAVE NOT BEEN HANDLED WELL BY THE SHORT TERM GUIDANCE...WILL CONTINUE TO SHIFT NORTH THIS MORNING ALONG THE LEADING EDGE OF THE DIFLUENCE ALOFT DUE TO THE APPROACHING MID LEVEL SHORT WAVE TROF CURRENTLY EXTENDING FROM NORTHWEST IOWA EAST TOWARD THE QUAD CITIES. 15Z SURFACE ANALYSIS PUTS THE SURFACE LOW SOMEWHERE BETWEEN CALEDONIA AND PRESTON IN SOUTHEAST MINNESOTA WITH A WARM FRONT EXTENDING EAST TOWARD BARABOO WISCONSIN JUST NORTH OF THE WISCONSIN RIVER. A COLD FRONT THEN SAGS SOUTHWARD JUST WEST OF DECORAH AND EAST OF CHARLES CITY. THE HIGHEST SURFACE BASED INSTABILITY NOSES UP FROM ACROSS NORTHERN ILLINOIS INTO FAR NORTHEAST IOWA IN THE WARM SECTOR. MODIFIED 15Z LAPS AND RUC SOUNDINGS FROM THE WARM SECTOR NEAR OELWEIN SHOW ABOUT 2500 J/KG OF SFC BASED CAPE WITH THE CIN QUICKLY ERODING AND DOWN TO AROUND -50 J/KG. WITH TEMPERATURES RISING AND DEW POINTS IN THE MID TO UPPER 60S THIS AFTERNOON...INSTABILITY DOES NOT APPEAR TO BE AN ISSUE FOR DEVELOPING THUNDERSTORMS. WIND SHEAR REMAINS THE BIGGEST QUESTION MARK IN WHETHER THE STORMS WILL BE ABLE TO BECOME ORGANIZED. MID LEVEL WINDS DO APPEAR TO INCREASE AS THE SHORT WAVE APPROACHES BUT THE 11.14Z RUC KEEPS THE BEST 0-6KM SHEAR OUT AHEAD OF THE WARM SECTOR WITH ONLY ABOUT 20-30KTS OF SHEAR FORECAST WITH MUCH OF THIS SHEAR IN THE LOWEST 3KM. SO...THE CLOSER THAT THE STORMS INITIATE ALONG THE WARM FRONT...THE BETTER THE CHANCES WILL BE THAT THEY MAY ORGANIZE INTO SUPERCELLS OR HAVE A MORE SUSTAINED UPDRAFT TO BECOME SEVERE. THIS HIGHEST POTENTIAL WILL BE ACROSS WESTERN WISCONSIN WHERE THE INSTABILITY WILL BE THE HIGHEST ALONG WITH THE BETTER SHEAR AS THE SURFACE LOW LIFTS NORTHWARD. THE TORNADO THREAT CAN NOT BE RULED OUT AS WELL WITH THE BACKED SOUTHEASTERLY SURFACE WINDS ALONG THE WARM FRONT. THIS SEVERE THREAT WILL BE A FAIRLY QUICK SHOT THIS AFTERNOON AS THE MID LEVEL SHORT WAVE WILL ALREADY BE INTO NORTH CENTRAL WISCONSIN BY THIS EVENING. && .PREV DISCUSSION... /ISSUED 414 AM CDT WED MAY 11 2011/ SHORT TERM...TODAY THROUGH FRIDAY FOR TODAY...IT LOOKS LIKE THE FORECAST AREA IS GOING TO BE AFFECTED BY TWO SHORT WAVES. THE FIRST WAVE...CURRENTLY LOCATED OVER SOUTHERN AND WESTERN IOWA...WILL MAINLY AFFECT SOUTHEAST MINNESOTA AND NORTHEAST IOWA THIS MORNING. DUE TO THIS...THE PRECIPITATION CHANCES WERE RAISED INTO THE 60 TO 90 PERCENT RANGE. THERE DOES NOT APPEAR TO BE MUCH 0-6KM SHEAR ASSOCIATED WITH THIS WAVE...SO NOT THINKING THAT THERE WILL NOT BE MUCH SEVERE WEATHER POTENTIAL WITH IT. THE SECOND WAVE...CURRENTLY LOCATED ACROSS SOUTHEAST KANSAS... NORTHEAST OKLAHOMA...SOUTHERN MISSOURI...AND ARKANSAS...WILL MOVE INTO THE FORECAST AREA THIS AFTERNOON. WHILE MUCH OF THE FORCING WITH THIS WAVE SHOULD BE LOCATED ACROSS WISCONSIN...MANY OF THE MODELS SUGGEST THAT THERE MAY BE SOME INTERACTION BETWEEN THIS WAVE AND THE ONE THIS MORNING. SOME PARTIAL SUNSHINE THIS MORNING ACROSS WESTERN WISCONSIN WILL ALLOW MEAN LAYER CAPES TO CLIMB INTO THE 2000 TO 3000 J/KG RANGE PRIOR TO ITS ARRIVAL. IN ADDITION... BOTH THE DETERMINISTIC GFS AND NAM/WRF SUGGESTS THAT THE 0-6 KM SHEAR WILL APPROACH 40 KNOTS ACROSS SOUTHWEST AND CENTRAL WISCONSIN. MEANWHILE THE 10.21Z SREF ENSEMBLES ARE NOT THAT IMPRESSIVE AT ALL WITH THE SHEAR. THE 11.00Z SPC WRF AND 11.05Z HRRR DOES GIVE AN INDICATION THAT THERE MAY BE SOME INITIAL SUPERCELLS ACROSS SOUTHWEST AND CENTRAL WISCONSIN. IF SEVERE WEATHER DOES HAPPEN TO DEVELOP...LARGE HAIL AND DAMAGING WINDS LOOK TO BE THE MAIN SEVERE WEATHER THREAT. THERE MAY BE EVEN AN ISOLATED TORNADO IN THE VICINITY OF THE WARM FRONT /NEAR THE INTERSTATE 90 CORRIDOR/. THE BEST PROBABILITIES OF SEVERE WEATHER LOOKS TO BE FROM 1 PM TO 6 PM. AS FAR AS THIS EVENING...SUBSIDENCE SHOULD SPREAD INTO THE AREA FROM THE SOUTH AND WEST. AS A RESULT...THE PRECIPITATION MAY BE MAINLY CONFINED TO THE EARLY PARTS OF THE EVENING. AFTER MIDNIGHT TONIGHT...ANOTHER WAVE WILL BE APPROACHING NORTHEAST IOWA AND SOUTHWEST WISCONSIN. DUE TO THIS...THE PRECIPITATION CHANCES WERE LEFT ALONE ACROSS THESE AREAS. MEANWHILE AREAS ALONG AND NORTH OF THE INTERSTATE 90 CORRIDOR MAY NOT SEE MUCH PRECIPITATION AT ALL. DUE TO THIS...THE PRECIPITATION CHANCES WERE LOWERED FOR THESE AREAS. ON THURSDAY...THE UPPER LEVEL LOW WILL BEGIN TO AFFECT THE AREA. DUE TO THIS...THE LIKELY /60 PERCENT/ PRECIPITATION PROBABILITIES WERE LEFT ALONE. WITH MEAN LAYER CAPES LESS THAN 1000 J/KG AND LITTLE 0-6 KM SHEAR...NOT IMPRESSED AT ALL WITH THE SEVERE WEATHER CHANCES. FOR THURSDAY NIGHT INTO FRIDAY...THE MODELS ARE BECOMING MUCH LESS CONSISTENT WITH THEIR PRECIPITATION. IN ADDITION...THERE IS LITTLE CONSENSUS AMONGST THEM. DUE TO THIS...THE PRECIPITATION CHANCES WERE LOWERED A BIT. LONG TERM...FRIDAY NIGHT THROUGH TUESDAY ON FRIDAY NIGHT...BOTH THE GFS AND GEM GENERATE SOME LIGHT PRECIPITATION ACROSS THE AREA. MEANWHILE BOTH THE NAM/WRF AND ECMWF IS DRY. SINCE THERE IS SUCH A DIFFERENCE THE PRECIPITATION CHANCES WERE LOWERED A BIT. FROM SATURDAY THROUGH SUNDAY EVENING...THE 11.00Z MODELS ARE IN GOOD AGREEMENT THAT THE AREA WILL BE AFFECTED BY AN UPPER LEVEL LOW. THIS LOW WILL KEEP SKIES MOSTLY CLOUDY AND MAXIMUM TEMPERATURES WILL STRUGGLE TO GET OUT OF THE 50S. IN ADDITION...THERE WILL BE SOME SCATTERED SHOWERS. FOR THE REMAINDER OF THIS TIME PERIOD...THE MODELS ARE IN GOOD AGREEMENT THAT AN UPPER LEVEL RIDGE WILL BE IN CONTROL OF THE AREA/S WEATHER. HOWEVER THERE IS SOME DISAGREEMENT STARTING TO SHOW UP BETWEEN THE ECMWF AND GFS TOWARD THE MIDDLE OF NEXT WEEK. THIS DEALS WITH THE ECMWF NOW SHOWING THE UPPER LEVEL LOW MAY RETROGRADE BACK TOWARD THE AREA. IF THIS DOES INDEED OCCUR...THE MAXIMUM TEMPERATURES FOR TUESDAY MAY HAVE TO BE LOWERED SOME. AVIATION...TODAY AND TONIGHT TWO WAVES OF PRECIPITATION ARE EXPECTED TO COME INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION TODAY. THE FIRST ONE MOVING INTO WESTERN IOWA EARLY THIS MORNING SHOULD SPREAD EAST TOWARDS KRST BETWEEN 14 AND 18Z. CONFIDENCE NOT HIGH AT THE MOMENT OF THE PRECIPITATION AFFECTING KRST...AS IT COULD STAY TO THE WEST. HOWEVER WILL CONTINUE TO MONITOR THE NEED TO INTRODUCE IT. IF THE PRECIPITATION WERE TO AFFECT KRST...THE MAIN IMPACT WOULD BE SOME ISOLATED THUNDER AS BOTH VSBYS AND CEILINGS SHOULD STAY VFR. THE NEXT WAVE OF PRECIPITATION FOR TODAY IS CURRENTLY IN NORTHEAST OKLAHOMA...WHICH WILL MOVE INTO THE AREA THIS AFTERNOON. VCTS MENTIONS HAVE BEEN INCLUDED FOR THIS WAVE AT BOTH TAF SITES...THOUGH KLSE LOOKS MORE FAVORABLE FOR VCTS THAN KRST. EVEN THEN...MOST OF THE STORM ACTION COULD OCCUR EAST OF KLSE. SIMILAR TO THIS MORNING...VSBYS AND CEILINGS ARE EXPECTED TO STAY VFR THIS AFTERNOON. MOST PRECIPITATION SHOULD BE DONE WITH BY 00Z...OR AT LEAST BE EAST OF THE TAF SITES. A SURGE OF MOISTURE AND INSTABILITY FROM THE SOUTH IS EXPECTED LATE TONIGHT...BUT ANY PRECIPITATION RESULTING FROM THIS SURGE SHOULD STAY SOUTH OF THE TAF SITES. THEREFORE...HAVE MAINTAINED A VFR FORECAST FOR TONIGHT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && UPDATE...HALBACH SHORT/LONG TERM...BOYNE AVIATION...AJ
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 1010 AM CDT WED MAY 11 2011 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034- 041>044-053>055-061-121200- ADAMS-ALLAMAKEE-BUFFALO-CHICKASAW-CLARK-CLAYTON-CRAWFORD-DODGE- FAYETTE-FILLMORE-FLOYD-GRANT-HOUSTON-HOWARD-JACKSON-JUNEAU-LA CROSSE- MITCHELL-MONROE-MOWER-OLMSTED-RICHLAND-TAYLOR-TREMPEALEAU-VERNON- WABASHA-WINNESHIEK-WINONA- 1010 AM CDT WED MAY 11 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND SOUTHWEST INTO CENTRAL WISCONSIN. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS ARE POSSIBLE THIS MORNING MAINLY WEST OF LINE FROM EAU CLAIRE SOUTH ALONG THE MISSISSIPPI RIVER. LIGHTNING...SMALL HAIL AND BRIEF HEAVY RAIN WILL BE THE MAIN HAZARDS WITH THEM. THUNDERSTORMS ARE EXPECTED TO REDEVELOP EARLY THIS AFTERNOON AND THEN MOVE NORTHEAST OF THE AREA BY THIS EVENING. LARGE HAIL...DAMAGING WINDS...BRIEF HEAVY RAIN AND LIGHTNING ARE ALL POSSIBLE FROM THESE THUNDERSTORMS. IN ADDITION...THERE IS THE POTENTIAL FOR SOME TORNADOES THIS AFTERNOON...MAINLY ACROSS WESTERN WISCONSIN WHERE A WARM FRONT WILL BE LIFTING NORTH THROUGH THE STATE. THERE IS A CHANCE OF THUNDERSTORMS TONIGHT...MAINLY AFTER MIDNIGHT AND SOUTH OF INTERSTATE 90. LIGHTNING AND BRIEF HEAVY RAIN WILL BE THE MAIN HAZARDS WITH THEM. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THUNDERSTORM CHANCES CONTINUE INTO THURSDAY. AT THIS TIME SEVERE WEATHER APPEARS UNLIKELY. HOWEVER...ANY STORMS THAT OCCUR WILL PRODUCE BRIEF HEAVY RAIN AND LIGHTNING. SOME SMALL HAIL AND GUSTY WINDS FROM THE STORMS CANNOT BE RULED OUT EITHER. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON...PARTICULARLY ACROSS SOUTHEAST MINNESOTA AND SOUTHWEST INTO CENTRAL WISCONSIN. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. AJ/HALBACH
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 958 AM CDT WED MAY 11 2011 WIZ032-033-111600- BUFFALO-TREMPEALEAU- 958 AM CDT WED MAY 11 2011 AT 950 AM...DOPPLER RADAR INDICATED STRONG THUNDERSTORMS OVER NORTHEAST BUFFALO COUNTY...MOVING NORTHEAST AT 10 MPH. PEA SIZE HAIL AND BRIEF HEAVY RAIN MAY ACCOMPANY THESE STRONG THUNDERSTORMS. LOCATIONS AFFECTED INCLUDE... MONDOVI AND MONDOVI AIRFIELD JW
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 1100 AM CDT WED MAY 11 2011 MNZ079-WIZ032-111700- BUFFALO-WABASHA- 1100 AM CDT WED MAY 11 2011 AT 1055 AM...DOPPLER RADAR INDICATED STRONG THUNDERSTORMS FROM THE BIG SWAMP AREA TO WABASHA...MOVING NORTH AT 40 MPH. PENNY SIZE HAIL MAY ACCOMPANY THESE STRONG THUNDERSTORMS. LOCATIONS AFFECTED INCLUDE... MAXVILLE AND NELSON. JW
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 1104 AM CDT WED MAY 11 2011 WIZ017-029-111700- CLARK-TAYLOR- 1104 AM CDT WED MAY 11 2011 AT 1059 AM...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER JUNCTION...MOVING NORTHEAST AT 20 MPH. PENNY SIZE HAIL MAY ACCOMPANY THIS STRONG THUNDERSTORM. LOCATIONS THAT MAY BE AFFECTED INCLUDE... LUBLIN...POLLEY...GILMAN...THE MILLER DAM FLOWAGE AND DONALD. JW
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 1247 PM CDT WED MAY 11 2011 WIZ017-111815- TAYLOR- 1247 PM CDT WED MAY 11 2011 AT 1240 PM...DOPPLER RADAR INDICATED STRONG THUNDERSTORMS ACROSS EXTREME NORTHWEST TAYLOR COUNTY...MOVING NORTH AT 40 MPH. PENNY SIZE HAIL AND HEAVY RAIN WILL ACCOMPANY THESE STRONG THUNDERSTORMS. LOCATIONS IMPACTED INCLUDE... JUMP RIVER. JW
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 154 PM CDT WED MAY 11 2011 WIZ034-042>044-112045- ADAMS-JACKSON-JUNEAU-MONROE- 154 PM CDT WED MAY 11 2011 ...STRONG TO SEVERE THUNDERSTORMS MOVING THROUGH CENTRAL WISCONSIN... AT 152 PM...DOPPLER RADAR INDICATED A LINE OF STRONG TO SEVERE THUNDERSTORMS FROM FORT MC COY TO NEAR TOMAH...TO JUST NORTHWEST OF THE WISCONSIN DELLS. THE STORMS WERE MOVING NORTHEAST AT 15 MPH. SOME OF THESE STORMS MAY BE SEVERE WITH QUARTER-SIZED HAIL AND WINDS TO 60 MPH. LOCATIONS THAT MAY BE AFFECTED THROUGH 3 PM INCLUDE... NEW LISBON...NECEDAH...DELLWOOD...ADAMS AND FRIENDSHIP. A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM WEDNESDAY EVENING FOR CENTRAL WISCONSIN. PREPARE NOW FOR POSSIBLE SEVERE WEATHER. MOVE INDOORS AND IF A WARNING IS ISSUED...TAKE ACTIONS TO PROTECT LIFE AND PROPERTY.
The La Crosse radar (KARX), 63 km away, was scanning. The volume nearest the first event began at 18:59 UTC.
4 hail. Local standard time, as filed.
Hail ranging in size from ping pong to golf ball created damage to police cars east-southeast of Tomah on State Highway 16.
Dime size hail fell at the intersection of State Highway 21 and Interstate 94.
Penny size hail fell six miles north-northeast of Plainville.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2011Every state in 2011This day in weather historyWarnings in Wisconsin, 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: 301266, 301269, 301273, 301274.