Thunderstorms that developed ahead of a weak cold front and an upper level disturbance produced wind damage, and isolated large hail, in central Wisconsin. Winds from the storms snapped and uprooted trees, downed power lines, and caused minor damage to two buildings.
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 GRB wrote it up.
Thunderstorms that developed ahead of a weak cold front and an upper level disturbance produced wind damage, and isolated large hail, in central Wisconsin. Winds from the storms snapped and uprooted trees, downed power lines, and caused minor damage to two buildings.
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 Green Bay, WI wrote its last area forecast discussion before the first event at Sep 4, 5:08 PM CST, 22 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 608 PM CDT TUE SEP 4 2012 .UPDATE...SVR STORMS VERY SLOWLY MAKING THEIR WAY TOWARD THE AREA FM THE W. THE STRONGEST STORMS WERE DROPPING SE...SO IT LOOKS LIKE THE SW CORNER OF THE AREA WL BE AT GREATEST RISK OF GETTING SVR WX. STORMS HAVE BEEN PRIMARILY HAIL PRODUCERS THUS FAR...BUT SHOWING SOMESIGNS OF BETTER WIND POTENTIAL WITHIN THE PAST 20 MINUTES OR SO. EXPECT INSTABILITY TO WANE NOW THAT WE ARE APPROACHING SUNSET. AT THIS POINT...WOULD NOT ANTICIPATE THE NEED TO EXTEND THE WATCH ANY FARTHER E. SHOULD BE SOME FG POTENTIAL AGAIN LATE TNGT. THOUGH SET-UP NOT AS GOOD AS WE HAD THIS MORNING. SKOWRONSKI && .PREV DISCUSSION...ISSUED AT 223 PM CDT TUE SEP 4 2012... SHORT TERM...TNGT AND WED. ACTIVE WEATHER PERIOD EXPECTED OVER THE NEXT 24 HOURS AS INITIAL CONVECTIVE ACTIVITY AHEAD OF WEAK SFC TROF MOVES ACROSS THE REGION THIS EVENING. THIS ACTIVITY TO BE FOLLOWED BY ANOTHER ROUND OF SHOWERS/THUNDERSTORMS LATE TNGT THRU MOST OF WED ASSOCIATED WITH A CDFNT. TRYING TO TIME BOTH OF THESE PCPN CHCS TO BE THE PRIMARY FCST FOCUS. THE 19Z MSAS SFC ANALYSIS INDICATED A WEAK AREA OF HI PRES OVER LWR MI...WHILE A SFC TROF WAS LOCATED ON THE MN/WI BORDER. THE ATMOSPHERE IS PRIMED FOR THUNDERSTORM DEVELOPMENT OVER WI WITH STRONG INSTABILITY AND A LOT OF MOISTURE AVAILABLE. STILL EXPECT TO SEE CONVECTION FIRE LATE THIS AFTERNOON OVER ERN MN/WRN WI AHEAD OF THE SFC TROF WITH PLENTY OF INSTABILITY/LOW- LEVEL MOISTURE IN PLACE. THESE STORMS COULD BE STRONG TO SEVERE GIVEN THE MODERATE AMOUNT OF SHEAR OVER THE REGION HEADED INTO THE EARLY EVENING HOURS. AS SFC HEATING WANES THIS EVENING...EXPECT THUNDERSTORM ACTIVITY TO DIMINISH TOWARD ERN WI...THUS HIGHEST POPS HAVE BEEN PLACED ACROSS CNTRL WI. WEAK SUBSIDENCE SHOULD ALLOW FOR SKIES TO TEMPORARILY BECOME PARTLY CLOUDY AND WITH LIGHT WINDS/DEW PTS IN THE 60S...WE COULD SEE SOME PATCHY FOG DEVELOP ONCE AGAIN AND HAVED ADDED THIS TO THE FCST. THE BREAK IN PCPN CHCS TO BE SHORT-LIVED AS A STRONG SHORTWAVE TROF/ATTENDANT CDFNT SWEEP INTO THE UPR MS VALLEY LATER TNGT. ONSET OF WAA AND PRE- FRONTAL ASCENT WL GENERATE A LARGE AREA OF SHOWERS/THUNDERSTORMS WHICH WL BE APPROACHING THE FCST AREA BY DAYBREAK. SHOWERS/THUNDERSTORMS WL SWEEP ACROSS NE WI WED MORNING AND QUICKLY PUSH TO THE EAST DURING THE AFTERNOON. EVEN THO TIMING OF THE COLD FRONTAL PASSAGE IS NOT IDEAL...STRENGTH OF THE MID-LEVEL SPEED MAX ACCOMPANIED BY FRONTAL LIFT...MODERATE INSTABILITY... STRONG SHEAR AND PLENTY OF MOISTURE...COULD BRING A ROUND OF STRONG TO SEVERE STORMS TO MOST OF THE REGION DURING THE MORNING HOURS BEFORE DRYING CONDITIONS BEGIN TO ADVECT INTO THE REGION DURING THE AFTERNOON. MAX TEMPS TO BE HELD DOWN BY CLOUDS/PCPN IN THE MORNING BEFORE SOME CLEARING LATER IN THE DAY ALLOWS TEMPS TO RECOVER INTO THE 75-80 DEG RANGE. LONG TERM...WEDNESDAY NIGHT THROUGH NEXT TUESDAY. COOLER AND DRIER AIR BUT STILL CLOSER TO NORMAL TEMPERATURES EXPECTED FOR THE REMAINDER OF THE WEEK IN THE WAKE OF A COLD FRONT ON WEDNESDAY. SURFACE HIGH PRESSURE SYSTEM TO DRIFT OVER THE REGION WEDNESDAY NIGHT INTO THURSDAY. ANOTHER SHORT WAVE TROUGH WITH COLD FRONT IS EXPECTED TO DROP OVER THE STATE THURSDAY NIGHT INTO FRIDAY. WILL CONTINUE THE SHOWERS MENTION DUE TO THE FRONT AND UPPER JET SUPPORT. THESE FEATURES DRIFT SOUTH OF AREA BY FRIDAY NIGHT. WILL KEEP A CHANCE LINGERING OVER THE SOUTHEAST PORTION FRIDAY NIGHT DUE TO THE UPPER LOW STILL DROPPING SOUTH. MEDIUM RANGE MODELS HAVE TRENDED TOWARD A BETTER CONSENSUS WITH THE PROGRESSION WITH THE UPPER LOW THIS WEEKEND. THE PREVIOUS LOWER ECMWF HAS TRENDED TOWARD THE MORE PROGRESSIVE UK AND GFS...SO WILL KEEP THE DRY FORECAST WITH LESS CLOUDS FOR THE WEEKEND GOING. OVERALL QUIET WEATHER ANTICIPATED AS AN UPPER RIDGE BUILDS INTO THE NORTHERN AND CENTRAL PLAINS...LEAVING THE FORECAST AREA IN THE A NORTHWEST FLOW REGIME. PERHAPS A WARM UP FAR THE EARLY PART OF NEXT WEEK DEPENDING ON HOW FAST THE UPPER RIDGE DRIFTS EAST WITH THE RETURN FLOW OVER THE GREAT LAKES REGION. && .AVIATION...FOR 00Z TAF ISSUANCE. TSTMS WL BE THE MAIN AVIATION HAZARD THIS EVENING. LOOKS LIKE THE STRONGEST STORMS WL TRACK ACRS THE SW PART OF THE AREA...PROBABLY TO THE S AND W OF AUW/CWA. COULD BE A PERIOD OF FAIRLY WIDESPREAD IFR/LIFR CONDITIONS LATER TNGT AS FG ONCE AGAIN FORMS. BUT WINDS JUST ABV THE SFC WL BE STRONGER THAN 24 HRS AGO...ESP LATE TNGT. ALSO...INCOMING CLDS AHEAD OF THE NEXT UPR SHRTWV WL ALSO ARRIVE LATE AT NGT. BOTH THOSE FACTORS SHOULD KEEP VSBYS FM BECOMING AS POOR AS THEY DID EARLY THIS MORNING. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREEN BAY WI 1153 AM CDT TUE SEP 4 2012 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-051700- VILAS-ONEIDA-FOREST-FLORENCE-NORTHERN MARINETTE-LINCOLN-LANGLADE- MENOMINEE-NORTHERN OCONTO-DOOR-MARATHON-SHAWANO-WOOD-PORTAGE- WAUPACA-OUTAGAMIE-BROWN-KEWAUNEE-WAUSHARA-WINNEBAGO-CALUMET- MANITOWOC-SOUTHERN MARINETTE-SOUTHERN OCONTO- 1153 AM CDT TUE SEP 4 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST WISCONSIN. .DAY ONE...THIS AFTERNOON AND TONIGHT THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THE UPPER MISSISSIPPI VALLEY THIS AFTERNOON AND MOVE TOWARD CENTRAL WISCONSIN BY EARLY EVENING. THERE IS A POSSIBILITY THAT SOME OF THESE STORMS COULD BECOME SEVERE WITH THE MAIN HAZARDS BEING LARGE HAIL AND DAMAGING WINDS. THE THUNDERSTORMS ARE THEN FORECAST TO REACH EASTERN WISCONSIN LATER IN THE EVENING...BUT WEAKEN IN THE PROCESS. ANOTHER ROUND OF THUNDERSTORMS IS THEN EXPECTED TO DEVELOP LATE TONIGHT AND APPROACH CENTRAL WISCONSIN TOWARD DAYBREAK. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY A SLIGHT RISK OF SEVERE THUNDERSTORMS WILL CONTINUE OVER THE ENTIRE AREA THROUGH AT LEAST WEDNESDAY MORNING AS AN UPPER LEVEL DISTURBANCE AND COLD FRONT MOVE ACROSS THE AREA. DAMAGING WINDS AND LARGE HAIL ARE THE MAIN THREAT. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION COULD BE NEEDED THIS EVENING AND AGAIN LATE TONIGHT INTO WEDNESDAY MORNING. LMZ521-522-541>543-051700- THE BAY OF GREEN BAY SOUTH OF A LINE FROM CEDAR RIVER MI TO ROCK ISLAND PASSAGE-LAKE MICHIGAN FROM WASHINGTON ISLAND TO SHEBOYGAN- 1153 AM CDT TUE SEP 4 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST LAKE MICHIGAN AND THE WATERS OF GREEN BAY. .DAY ONE...THIS AFTERNOON AND TONIGHT THERE IS A CHANCE OF THUNDERSTORMS THIS EVENING. A FEW OF THESE STORMS COULD BE SEVERE WITH LARGE HAIL AND DAMAGING WINDS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THUNDERSTORMS ARE LIKELY WEDNESDAY. ISOLATED STRONG THUNDERSTORMS WITH GUSTY WINDS AND HAIL ARE POSSIBLE. AK
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREEN BAY WI 618 PM CDT TUE SEP 4 2012 WIZ030-035-036-050015- MARATHON-PORTAGE-WOOD- 618 PM CDT TUE SEP 4 2012 ...STRONG THUNDERSTORMS TO AFFECT WESTERN MARATHON COUNTY... AT 615 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER EASTERN CLARK COUNTY...MOVING EAST AT 35 MPH. PENNY SIZE HAIL...WINDS TO 45 MPH...CONTINUOUS CLOUD TO GROUND LIGHTNING...ARE POSSIBLE WITH THIS STORM AS IT MOVES INTO WESTERN MARATHON COUNTY. * THE THUNDERSTORM WILL BE NEAR... SPENCER BY 625 PM CDT... MARSHFIELD BY 635 PM CDT... GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW AROUND. STAY INDOORS UNTIL THE STORM PASSES. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED. EB
The La Crosse radar (KARX), 127 km away, was scanning. The volume nearest the first event began at 23:28 UTC.
11 thunderstorm wind, 1 hail. Local standard time, as filed.
Thunderstorms produced sustained winds estimated near 40 mph with gusts to 60 mph in Spencer.
Thunderstorm wind gusts to 60 mph downed trees, some as large as 8 inches in diameter, west of Marshfield.
Thunderstorm winds blew in the glass window at a gas station and downed power lines south of Stratford.
Thunderstorms produced penny size hail southwest of Junction City.
Thunderstorm winds downed a large tree that fell onto and damaged a deck.
A thunderstorm wind gust, estimated at 80 mph, bent a highway sign to the ground. The sign, at the STH 29 and U.S. Highway 51 interchange, was on steel posts that bent at the base.
Thunderstorm winds blew off part of a roof of a metal building system near Rothschild.
Thunderstorm winds snapped and uprooted several trees in the Town of Kronenwetter.
Thunderstorm winds, with gusts of 60 to 70 mph, snapped two railroad crossing gates, blew construction barrels across roads, and snapped several trees along Old Highway 51 between Kowalski Road and Exit 181.
Thunderstorms produced wind gusts estimated at 60 mph in Plover.
Thunderstorm winds downed a few trees and many branches just north of Big Falls.
Thunderstorms produced wind gusts estimated at 60 mph in Clintonville.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2012Every state in 2012This day in weather historyWarnings in Wisconsin, September 2012
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: 408832, 408823, 408824, 408822, 408825, 408827, 408835, 408828, 408830, 408833, 408831, 408834.