Severe thunderstorms produced damaging winds during the morning hours of September 2nd across portions of southwest and central Wisconsin. Law enforcement, trained spotters and National Weather Service employees reported numerous trees and power lines down from La Crosse, Trempealeau and Vernon counties eastward to Adams County.
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.
Severe thunderstorms produced damaging winds during the morning hours of September 2nd across portions of southwest and central Wisconsin. Law enforcement, trained spotters and National Weather Service employees reported numerous trees and power lines down from La Crosse, Trempealeau and Vernon counties eastward to Adams County. Over 10,000 residents loss power and schools were either delayed for two hours or closed in these areas.
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 Sep 2, 1:30 AM CST, 4 hours 52 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 230 AM CDT FRI SEP 2 2011 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT FORECAST CONCERNS FOCUS ON THE STORM THREAT OVER THE NEXT COUPLE DAYS...THEN MUCH COOLER AIR FOR THE END OF THE WEEKEND. THUNDERSTORMS CONTINUE TO SPARK OVER THE CENTRAL/NORTHERN PLAINS EARLY THIS MORNING...AHEAD OF AN UPPER LEVEL SHORTWAVE TROUGH DRIVING ACROSS THE WESTERN DAKOTAS //PER WATERVAPOR SATELLITE IMAGERY//. AT THE SFC A FRONT RAN FROM THE MN ARROWHEAD SOUTHEAST INTO NEB. THIS SHORTWAVE TROUGH WILL CONTINUE ITS EASTWARD TRACK TODAY...KEEPING THE BULK OF THE ITS ENERGY TO THE NORTH. THE TROUGH WILL GIVE THE NORTHERN PORTION OF THE FRONT A PUSH EAST THOUGH...TAKING ON A MORE WEST-EAST ORIENTATION ACROSS NORTHERN IA/SOUTHERN WI BY LATE THIS AFTERNOON. SOME 2-D FRONTOGENETIC FORCING AROUND THE BOUNDARY...WITH WEAK BUT PERSISTENT 925-700 MB MOISTURE TRANSPORT INTO IT. THIS SHOULD BE ENOUGH TO CONTINUE/SPARK SHOWERS/STORMS IN THE VICINITY OF THE BOUNDARY TODAY DESPITE DECENT LOW LEVEL CAPPING INVERSION. TONIGHT...BOUNDARY WILL LIKELY CONTINUE TO WAVER JUST TO THE SOUTH...WITH AN INCREASING LOW LEVEL JET AND MOISTURE TRANSPORT INTO IT ALONG WITH AN UPPER LEVEL DISTURBANCE SPINNING OUT OF THE CENTRAL PLAINS. WOULD EXPECT ANOTHER AREA OF SHOWERS/STORMS TO BLOSSOM IN RESPONSE TO THIS FORCING. 1000-2500 J/KG OF MUCAPE AROUND AND NORTH OF THE BOUNDARY...WITH UP TO 40 KTS OF 0-6 KM SHEAR INDICATED TODAY. TONIGHT 500-1000 J/KG OF CAPE IN THE 1-6 KM LAYER WITH 30-40 KTS OF 0-6 KM SHEAR PERSISTING. CERTAINLY SOME STORM ORGANIZATION WILL BE POSSIBLE...WITH THE POTENTIAL FOR STRONG TO SEVERE STORMS. CONFIDENCE ISN/T HIGH IN WHEN/WHERE THE GREATER THREAT WILL BE...WITH CONVECTION IN THE WEST MOVING IN THIS MORNING...MODIFYING THE ATMOSPHERE AND ADDING AN ELEMENT OF UNCERTAINTY. SITUATION WILL HAVE TO BE MONITORED CLOSELY THROUGH THE DAY/NIGHT. ANOTHER UPPER LEVEL SHORTWAVE TROUGH WILL BEAR DOWN ON THE UPPER MISSISSIPPI RIVER VALLEY SATURDAY/SAT NIGHT...PUSHING ITS ASSOCIATED SFC COLD FRONT WELL AHEAD OF IT AND ACROSS THE REGION DURING THE DAY. THE 02.00Z GFS IS A BIT FASTER THAN THE NAM IN THIS STEAD. THIS SYSTEM GIVES THE LINGERING FRONT A FURTHER PUSH SOUTH...BUT WOULD ALSO BRING ANOTHER FOCUS FOR MORE SHOWERS/STORMS AS FRONTOGENETIC FORCING ALONG THIS COLD FRONT INTERACTS WITH WEAK MOISTURE TRANSPORT AND INSTABILITY. ENOUGH SHEAR TO FAVOR THE POTENTIAL FOR STORM ORGANIZATION AND STRONG/SEVERE DEVELOPMENT. THIS RISK MIGHT BE SHIFTED MORE EAST/SOUTH OF THE FORECAST AREA. WINDS WILL PICK UP ON SUNDAY POST THE SYSTEM WITH WRAP AROUND MOISTURE AROUND THE EXITING LOW LEADING TO MORE CLOUDS ACROSS THE NORTH. MORE SIGNIFICANTLY WITH THIS SYSTEM IS THAT A STRONG SLUG OF COLD AIR ADVECTION WILL LEAD TO TUMBLING TEMPS...DROPPING FROM 14 C AT 850 MB AT 00Z SUN TO 7 C BY 00Z MON. LOOK FOR A MUCH COOLER END TO THE EXTENDED HOLIDAY WEEKEND AS A RESULT WITH HIGHS IN THE 60S TO NEAR 70 AND LOWS FALLING OFF INTO THE 40S BY MONDAY MORNING. .LONG TERM...MONDAY THROUGH THURSDAY GFS AND ECMWF IN GOOD AGREEMENT WITH AMPLIFYING A FRIDGE OVER THE WEST COAST FOR NEXT WEEK...WHILE DEEPENING AN UPPER LEVEL TROUGH OVER THE EAST COAST. HIGH PRESSURE WOULD BE THE MAIN WEATHER INFLUENCE LOCALLY...RESULTING IN SEVERAL DRY DAYS WITH TEMPS NEAR THE SEASONABLE NORMALS. THERE DOES LIE THE POTENTIAL FOR SOME SHOWER/STORM CHANCES WED NIGHT AS A SHORTWAVE TROUGH SLIPS SOUTHEAST ACROSS THE GREAT LAKES. THE GFS HAS MORE ENERGY WEST WHICH LEADS TO A BETTER RAIN THREAT FOR THE UPPER MISSISSIPPI RIVER VALLEY. THE EC HINTS THAT IT COULD ALL STAY EAST. WILL LEAN ON THE CONSENSUS SOLUTION FOR THE DETAILS. && .AVIATION...TODAY THROUGH TONIGHT CURRENTLY WATCHING A COLD FRONT MOVING INTO FAR NORTHWEST WISCONSIN THROUGH WESTERN IA. RADAR MOSAIC SHOWING SHRA/TS ACTUALLY OCCURRING BEHIND THE FRONT CLOSER TO UPPER LEVEL SUPPORT. THE COLD FRONT IS EXPECTED TO SLIDE SOUTHEAST THROUGH THE AREA THIS MORNING WITH THAT POST-FRONTAL SHRA/TS ACTIVITY SPREADING INTO THE KRST/KLSE TAF SITES...REACHING KRST AROUND 10Z AND KLSE BY 13Z. VFR CONDITIONS EXPECTED WITHIN THIS SHRA/TS ACTIVITY THROUGH THIS MORNING AND EARLY AFTERNOON. MODEL SOUNDINGS/BUFKIT THEN INDICATE SOME LOWER MVFR STRATUS/STRATOCUMULUS LATER THIS AFTERNOON SPREADING ACROSS THE TAF SITES IN COLD AIR ADVECTION...LASTING INTO TONIGHT. FRONTAL BOUNDARY APPEARS TO STALL ACROSS SOUTHERN WI-CENTRAL IA OVERNIGHT FOR CONTINUED SCATTERED SHRA/ISOLD T ACTIVITY. THERE ARE INDICATIONS THAT VIS/CIG COULD EVEN FLIRT WITH IFR CONDITIONS AS THE VERY MOIST LOWER BOUNDARY LAYER COOLS OVERNIGHT/AFTER MIDNIGHT. WILL TAKE A CLOSER LOOK AT ALL THIS AND INCLUDE DETAILS WITH THE 02.12Z TAF ISSUANCE. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && SHORT/LONG TERM... RIECK AVIATION.......... DAS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 415 AM CDT FRI SEP 2 2011 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034- 041>044-053>055-061-031000- 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- 415 AM CDT FRI SEP 2 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF NORTHEAST IOWA... SOUTHEAST MINNESOTA...AND SOUTHWEST INTO CENTRAL WISCONSIN. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS WILL MOVE ACROSS THE AREA THIS MORNING...SOME OF WHICH COULD BE SEVERE PRODUCING DAMAGING WINDS AND LARGE HAIL. MORE THUNDERSTORMS WILL BE POSSIBLE LATER THIS AFTERNOON AND TONIGHT. THERE WOULD BE THE THREAT FOR STRONG...TO POSSIBLY SEVERE THUNDERSTORMS WITH THIS ACTIVITY. LARGE HAIL...DAMAGING WINDS...AND HEAVY RAIN WILL BE THE MAIN THREATS. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY A COLD FRONT WILL PROVIDE THE FOCUS FOR MORE THUNDERSTORMS ON SATURDAY. A FEW OF THESE STORMS COULD BECOME STRONG TO SEVERE...WITH THE HIGHER RISK OVER SOUTHERN WISCONSIN AND EASTERN IOWA. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS MORNING. FURTHER ACTIVATION COULD BE REQUESTED FOR LATER TODAY AND TONIGHT... AND POSSIBLY SATURDAY. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. RIECK
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
631 AM CDT FRI SEP 02 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0558 AM TSTM WND DMG OSAGE 43.28N 92.81W
09/02/2011 MITCHELL IA LAW ENFORCEMENT
TREE DOWN ON HOUSE.
&&
ZTPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
646 AM CDT FRI SEP 02 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0624 AM TSTM WND DMG CHESTER 43.49N 92.36W
09/02/2011 HOWARD IA EMERGENCY MNGR
SEVERAL POWER LINES DOWN
&&
ZTPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
702 AM CDT FRI SEP 02 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0558 AM TSTM WND DMG ST. ANSGAR 43.38N 92.92W
09/02/2011 MITCHELL IA TRAINED SPOTTER
8-10 INCH BRANCHES DOWN. ABOVE GROUND POOL FLIPPED OVER.
&&
ZTPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
707 AM CDT FRI SEP 02 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0635 AM TSTM WND DMG SPRING VALLEY 43.69N 92.39W
09/02/2011 FILLMORE MN AMATEUR RADIO
LARGE BRANCHES DOWN IN TOWN AND ONE TREE DOWN OVER COUNTY
ROAD 1.
&&
SHEAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
709 AM CDT FRI SEP 02 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0700 AM TSTM WND GST 2 NE NEWBURG 43.59N 91.80W
09/02/2011 E60 MPH FILLMORE MN TRAINED SPOTTER
SEVERAL BRANCHES DOWN. OUTSIDE FURNITURE BLOWN AROUND.
&&
ZTPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
715 AM CDT FRI SEP 02 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0710 AM TSTM WND GST 4 SW WINONA 44.01N 91.71W
09/02/2011 E60.00 MPH WINONA MN TRAINED SPOTTER
&&
ZTThe La Crosse radar (KARX), 32 km away, was scanning. The volume nearest the first event began at 12:20 UTC.
22 thunderstorm wind, 1 lightning. Local standard time, as filed.
Several trees were blown down along State Highway 35 between Centerville and Trempealeau.
Numerous trees were blown down with power outages in Stoddard and Genoa.
Several trees and power lines were blown down in the city of La Crosse. One tree went down on an apartment building on South 33rd Street with several trees down in the vicinity of the Shelby ball fields.
A house was destroyed by a fire started by a lightning strike.
An estimated 60 mile per hour wind gust occurred in Galesville.
The automated weather observing equipment at the La Crosse Municipal airport measured a wind gust of 63 miles per hour. A 62 mph gust was also measured at the same time in Onalaska.
A roof was blown off a house in Chaseburg.
An estimated wind gust of 60 miles per hour occurred in West Salem.
Several trees and power lines were blown down in and near Coon Valley. Especially hit hard, was the Norskedalen Nature & Heritage Center where more than 20 trees went down and several windows were broken by wind blown walnuts.
An estimated wind gust of 70 miles per hour occurred three miles northeast of Westby which knocked down a pine tree and caused damaged to a house.
At least 31 apple trees were blown down at the Maple Ridge Orchard.
A tree was blown down on a home with other trees down on power lines on Newport Road near Cashton.
A tree was blown down on a mobile home three miles southwest of Norwalk.
An estimated 60 mph wind gust blew down several large trees along County Road I four miles east of Cataract.
Numerous jack pine trees were snapped off, a 14 inch diameter tree blown down, and a large oak tree split four miles south of Norwalk.
Trees were blown down on power lines causing power outages in Wilton.
An estimated 60 mile per hour wind gust occurred in Tomah.
Large tree branches were blown down which caused siding and roof damage in Oakdale.
Numerous trees were blown down and other trees were snapped off from three miles southwest of Necedah to three miles southeast of Necedah.
Several trees were blown down near Sandstone Estates with one falling on trailer.
Several six inch diameter trees were blown down near Castle Rock Park.
Trees and power lines were blown down across portions of Adams County. The downed trees blocked roadways and fell on top of homes and cars. According to the emergency manager, it appears that Preston Township in the central part of the county, was hit the hardest with downed trees.
Trees and power lines were blown down four miles north of Friendship. One of these trees fell on a vehicle on State Highway 21 at the entrance of Roche-A-Cri State Park.
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, September 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: 341627, 341692, 341629, 341871, 341628, 341630, 341689, 341631, 341703, 341660, 342007, 341849, 341852, 341841, 341843, 341850, 341845, 341853, 341858, 341855, 341861, 341863, 341862.