A cold front, moving into a very moist and unstable air mass, triggered thunderstorms that produced damaging winds and heavy rainfall.
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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 GRB wrote it up.
A cold front, moving into a very moist and unstable air mass, triggered thunderstorms that produced damaging winds and heavy rainfall.
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 Jun 20, 1:26 PM CST, 3 hours 34 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 226 PM CDT WED JUN 20 2012 .SHORT TERM...TONIGHT AND THURSDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE LOW PRESSURE MOVING NORTHEAST OVER FAR NORTHWEST WISCONSIN...AND A COLD FRONT TRAILING TO SOUTH-CENTRAL MINNESOTA EARLY THIS AFTERNOON. SHOWERS AND STORMS ARE LIGHTING UP ALONG THE COLD FRONT AND SHOULD CONTINUE TO DO SO AS THE ATMOSPHERE DESTABILIZES WITH FURTHER HEATING...BUT NOTHING ORGANIZED AT THE MOMENT. RIGHT REAR QUAD OF AN UPPER JET STREAK AND FGEN ARE ALSO SPREADING OVER THE FRONT TO AID IN THE LARGE-SCALE ASCENT. BEHIND THE FRONT...SHOWERS AND ISOLATED STORMS ARE ALSO DEVELOPING OVER NORTH DAKOTA BENEATH AN UPPER TROUGH. AS THE FRONT SLOWLY MOVES EAST TONIGHT...SEVERE WEATHER IS THE MAIN FORECAST CONCERN. TONIGHT...THE UPPER TROUGH OVER THE NORTHERN PLAINS WILL PUSH A COLD FRONT ACROSS CENTRAL AND NORTH-CENTRAL WISCONSIN THIS EVENING...AND EAST-CENTRAL AND NORTHEAST WISCONSIN AFTER MIDNIGHT. EXPECT STRONG STORMS TO DEVELOP AHEAD OF THE FRONT THIS AFTERNOON WHERE ML CAPES WILL BE IN THE 1500-2000 J/KG RANGE OVER CENTRAL AND NORTHERN WISCONSIN. WITH A DECENT WIND FIELD AND EFFECTIVE SHEARS BETWEEN 30-35KTS...DAMAGING WINDS AND LARGE HAIL WILL BE THE PRIMARY THREATS IN THE THUNDERSTORMS AT LEAST INITIALLY OVER CENTRAL AND NORTH-CENTRAL WISCONSIN AS THE STORMS ARRIVE. INSTABILITY DOES DIMINISH FAIRLY QUICKLY THIS EVENING...SO EXPECT STORMS TO WEAKEN AS THEY MOVE EAST...PERHAPS TO AN ISOLATED SEVERE THREAT AS THEY ENTER THE FOX VALLEY AROUND MIDNIGHT. PWATS OF 1.80 INCHES AHEAD OF THE FRONT SHOULD ALLOW THE STORMS TO PRODUCE DECENT RAINFALL. SHOULD SEE THE STORMS MOVE OUT AFTER 09Z AND PARTIAL CLEARING TO MOVE IN IN ITS WAKE. LOWS IN THE MID 50S NORTH TO MID 60S SOUTH. THURSDAY...THE COLD FRONT WILL HAVE EXITED THE REGION BY 12Z THURSDAY AND COOLER AND DRIER AIR WILL HAVE FILTERED ACROSS THE AREA. THE UPPER TROUGH WILL SETTLE OVERHEAD THROUGH THE DAY AND PROGGED SOUNDINGS INDICATE LOW LEVEL INSTABILITY DEVELOPING WITH DAYTIME HEATING. DEFINITELY GOOD ENOUGH FOR A SUBSTANTIAL CU FIELD ESPECIALLY AFTER ALL THE RAINFALL LATELY. NOT SURE ABOUT A TRIGGER FOR SHOWER POSSIBILITIES...BUT THE 12Z NAM DOES INDICATE AN EMBEDDED SHORTWAVE SWINGING ACROSS THE AREA IN THE AFTERNOON THAT COULD INTERACT WITH 300-400 J/KG OF ML CAPE OVER N-C WISCONSIN. WILL LEAVE THE AREA DRY FOR NOW BUT MENTION POSSIBILITY TO THE NEXT SHIFT. HIGHS IN THE MID 70S NORTH TO LOW 80S SOUTH. .LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY. A NICE SEASONABLE PERIOD OF WEATHER EXPECTED WITH NORTHWEST UPPER FLOW AND A REFRESHING HUDSON BAY HIGH DROPPING SOUTH INTO THE GREAT LAKES EARLY NEXT WEEK. A JET STREAK MOVING THROUGH THE UPPER FLOW SHOULD COMBINE WITH COLD AIR ALOFT TO PRODUCE SOME SHOWERS AND THUNDERSTORMS FRIDAY ESPECIALLY IN THE NORTHEAST. ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY AND SATURDAY NIGHT AS MORE JET ENERGY MOVES THROUGH AND A REINFORCING COLD FRONT MOVES IN FROM THE NORTH. BIG SURFACE HIGH THEN SHOULD DROP SOUTH INTO THE GREAT LAKES AND BRING DRY AND COOL WEATHER FOR A GOOD PART OF NEXT WEEK. GFS SUGGESTS THAT THE AIR MAY BE DRY ENOUGH FOR A LATE SEASON FROST IN THE FAR NORTH TUESDAY NIGHT. WILL NOT MENTION YET IN THE HAZARDOUS WEATHER OUTLOOK YET DUE TO MODEL DIFFERENCES. && .AVIATION...A COLD FRONT WILL SLOWLY MOVE ACROSS CENTRAL AND EASTERN WISCONSIN LATE THIS AFTERNOON THROUGH LATE TONIGHT. SHOWERS AND STORMS WILL PUSH ACROSS THE REGION AHEAD OF THIS FRONT. SOME STORMS MAY BECOME STRONG TO SEVERE OVER CENTRAL AND NORTH-CENTRAL WISCONSIN LATE THIS AFTERNOON INTO EARLY THIS EVENING. CIGS AND VSBYS WILL LIKELY FALL TO MVFR IF NOT IFR IN ANY THUNDERSTORMS. IMPROVING CONDITIONS WILL BE FOUND BEHIND THE FRONT LATE TONIGHT INTO TOMORROW. LOOKING AT A FAIRLY WIDESPREAD DIURNAL CU FIELD TO DEVELOP BY LATE MORNING WHICH COULD LEAD TO HIGH END MVFR CIGS AT RHI FOR A FEW HOURS. MPC && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && MPC/RDM
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREEN BAY WI 229 PM CDT WED JUN 20 2012 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-211930- 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- 229 PM CDT WED JUN 20 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST WISCONSIN. .DAY ONE...TONIGHT THUNDERSTORMS ARE LIKELY ACROSS NORTH CENTRAL AND CENTRAL WISCONSIN THIS AFTERNOON...AND ACROSS THE ENTIRE AREA TONIGHT. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF NORTH CENTRAL... CENTRAL AND NORTHEAST WISCONSIN LATE THIS AFTERNOON AND EVENING... MAINLY FOR AREAS NORTHWEST OF THE FOX VALLEY AND LAKESHORE. DAMAGING STRAIGHT LINE WINDS...LARGE HAIL...AND TORRENTIAL RAINFALL ARE THE MAIN THREATS. THE HEAVY RAINFALL COULD RESULT IN SOME URBAN FLOODING. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH WEDNESDAY THERE IS A CHANCE OF THUNDERSTORMS FROM FRIDAY AFTERNOON THROUGH SATURDAY NIGHT...HOWEVER CONDITIONS ARE NOT EXPECTED TO BE FAVORABLE FOR SEVERE WEATHER. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED ACROSS PARTS OF NORTH CENTRAL... CENTRAL AND NORTHEAST WISCONSIN LATE THIS AFTERNOON AND EVENING. SPOTTERS ARE URGED TO RELAY REPORTS OF SEVERE WEATHER...FLOODING OR RAINFALL AMOUNTS IN EXCESS OF AN INCH TO THE NATIONAL WEATHER SERVICE IN GREEN BAY. LMZ521-522-541>543-211930- THE BAY OF GREEN BAY SOUTH OF A LINE FROM CEDAR RIVER MI TO ROCK ISLAND PASSAGE-LAKE MICHIGAN FROM WASHINGTON ISLAND TO SHEBOYGAN- 229 PM CDT WED JUN 20 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST LAKE MICHIGAN AND THE WATERS OF GREEN BAY. .DAY ONE...TONIGHT A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH TONIGHT... FOR INCREASING SOUTH WINDS AND BUILDING WAVES. THERE IS ALSO AN INCREASED RISK FOR RIP CURRENTS ALONG SOUTH FACING BEACHES ON LAKE MICHIGAN. THUNDERSTORMS WILL POSE A HAZARD TO BOATERS TONIGHT...WITH GUSTY WINDS AND HEAVY RAINFALL EXPECTED WITH THE STRONGER STORMS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH WEDNESDAY THERE IS A CHANCE OF THUNDERSTORMS FROM FRIDAY NIGHT THROUGH SATURDAY NIGHT...BUT SEVERE WEATHER IS NOT EXPECTED AT THIS TIME. MPC/RDM
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREEN BAY WI 323 PM CDT WED JUN 20 2012 WIZ005-010-018-202200- VILAS-ONEIDA-LINCOLN- INCLUDING THE CITIES OF...EAGLE RIVER...RHINELANDER...TOMAHAWK 323 PM CDT WED JUN 20 2012 ...SHOWERS AND THUNDERSTORMS HEADING TOWARDS THE NORTH WOODS... A SLOW MOVING LINE OF SHOWERS AND THUNDERSTORMS WILL ARRIVE IN BOULDER JUNCTION AND LAC DU FLAMBEAU BY 400 PM AND IN TOMAHAWK... RHINELANDER AND PHELPS BY 500 PM OR SO. RAINFALL RATES OF ONE TO TWO INCHES PER HOUR ARE POSSIBLE IN SOME AREAS...WHICH COULD CAUSE FLOODING OF SMALL STREAMS AND URBAN AREAS. WINDS COULD GUST TO 40 MPH WITH THE STRONGER STORMS. RDM
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREEN BAY WI 548 PM CDT WED JUN 20 2012 WIZ005-010>012-018-019-210115- VILAS-ONEIDA-FOREST-FLORENCE-LINCOLN-LANGLADE- INCLUDING THE CITIES OF...EAGLE RIVER...RHINELANDER...CRANDON... TOMAHAWK...ANTIGO 548 PM CDT WED JUN 20 2012 ...THUNDERSTORMS MOVING THROUGH NORTH CENTRAL WISCONSIN THIS EVENING... A SLOW MOVING LINE OF THUNDERSTORMS THAT WAS ACROSS VILAS COUNTY WILL CONTINUE TO MOVE THROUGH NORTH CENTRAL WISCONSIN THIS EVENING. THE STORMS MAY CONTAIN TORRENTIAL RAINFALL...THAT COULD CAUSE FLOODING OF SMALL STREAMS AND URBAN AREAS...ALONG WITH WIND GUSTS OF 40 TO 50 MPH WITH THE STRONGER STORMS. WIZ030-035-210115- MARATHON-WOOD- INCLUDING THE CITIES OF...WAUSAU...WISCONSIN RAPIDS 548 PM CDT WED JUN 20 2012 ...THUNDERSTORMS WILL MOVE INTO CENTRAL WISCONSIN THIS EVENING... A SLOW MOVING LINE OF THUNDERSTORMS WILL MAKE ITS WAY INTO CENTRAL WISCONSIN THIS EVENING. THE STORMS MAY CONTAIN TORRENTIAL RAINFALL...THAT COULD CAUSE FLOODING OF SMALL STREAMS AND URBAN AREAS...ALONG WITH WIND GUSTS OF 40 TO 50 MPH WITH THE STRONGER STORMS. MG
The Marquette radar (KMQT), 181 km away, was scanning. The volume nearest the first event began at 23:01 UTC.
3 thunderstorm wind, 1 heavy rain. Local standard time, as filed.
Heavy rain caused street flooding near the Oneida and Vilas County line. Weather observers reported one to three inches of rain in less than three hours.
Thunderstorm winds downed trees and a power line in Harshaw.
Thunderstorm winds blew down several power lines and a tree near Merrill.
Thunderstorms winds snapped three trees in Elcho. One of the trees landed on, and downed, a power line.
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, June 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: 392684, 387116, 394840, 387117.