An upper level disturbance and a cold front interacting with an unstable air mass resulted in the formation of thunderstorms. The strongest storms produced hail as large as tennis ball size and wind gusts to 60 mph.
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.
An upper level disturbance and a cold front interacting with an unstable air mass resulted in the formation of thunderstorms. The strongest storms produced hail as large as tennis ball size and wind gusts to 60 mph.
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 Jul 30, 2:33 PM CST, 47 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 333 PM CDT MON JUL 30 2012 .SHORT TERM...TONIGHT AND TUESDAY. THE POTENTIAL FOR SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND DURING THE EARLY EVENING IS THE MAIN CONCERN. A COLD FRONT WAS ACROSS NORTH CENTRAL WISCONSIN AT 20Z. THE FRONT AND AN UPPER LEVEL SHORT WAVE WILL CONTINUE THROUGH WISCONSIN AND INTERACT WITH AN UNSTABLE AIR MASS ACROSS THE AREA. LOCAL MESOANALYSIS GRAPHICS SHOWED A DECREASE IN DEEP LAYER SHEAR ACROSS NORTH CENTRAL WISCONSIN AND AN INCREASE OVER THE EASTERN PART OF THE STATE. LITTLE GOING ON AS OF 20Z...BUT STILL PLENTY OF DAYLIGHT HOURS LEFT. LACK OF SUFFICIENT LOW LEVEL MOISTURE COULD CAUSE THE WATCH TO BE A BUST. HIGH PRESSURE BUILDING INTO THE STATE BEHIND THE DEPARTING FRONT WILL KEEP THINGS DRY FOR LATE TONIGHT AND TUESDAY. HAVE PATCHY FOG IN MANY OF THE ZONES TONIGHT DUE TO LIGHT WINDS AND FOG IN THE MOS GUIDANCE. .LONG TERM...TUESDAY NIGHT THOUGH NEXT MONDAY. TREND OF THE MODELS THE LAST FEW RUNS CONTINUE TO FOCUS ON THE TWO MAIN SHORT WAVE TROUGHS WITH FRONTAL SYSTEMS TO TRACK OVER THE AREA. SURFACE HIGH PRESSURE WILL DOMINATE THE REGIONS WEATHER TUESDAY NIGHT INTO WEDNESDAY. RETURN FLOW WAA ON THE BACKSIDE OF THE HIGH BEGINS TO WORK INTO NORTHWEST WISCONSIN ON WEDNESDAY FOLLOWED WITH THE SHORT WAVE TROUGH WITH COLD FRONT PASSAGE. LATEST MODEL DATA SUGGEST A FASTER PASSAGE ON THURSDAY SO TONED DOWN THE PCPN ON THURSDAY AND THURSDAY NIGHT. FRONT DROPS INTO SOUTHERN WISCONSIN THROUGH FRIDAY AS A HIGH PRESSURE SYSTEMS DRIFTS OVER THE NORTHERN GREAT LAKES REGION. NEXT SHORT WAVE TROUGH PROGGED TO IMPACT THE AREA SOMETIME DURING THE FRIDAY NIGHT INTO SATURDAY NIGHT TIME FRAME. GFS RUN STILL TRACKS THE FRONT OVER ON SATURDAY BEFORE DEPARTING SATURDAY EVENING OVER EASTERN WISCONSIN. THE 12Z ECMWF RUN IS DELAYING THE PASSAGE OF THE UPPER TROUGH ABOUT 12 TO 18 HOURS SLOWER THAN THE GFS. WILL NOT MAKE ANY SIG CHANGES FOR THIS FEATURE AT THIS TIME. DRY HIGH PRESSURE TO SETTLE INTO THE REGION SUNDAY INTO MONDAY. && .AVIATION...THE MAIN CONCERN DURING THE TAF PERIOD IS THE POTENTIAL FOR SEVERE THUNDERSTORMS FROM ABOUT 1830Z UNTIL AROUND 03Z AS A COLD FRONT MOVES NW-SE ACROSS THE AREA. A STRONG UPPER LEVEL SHORT WAVE WILL ALSO PASS THROUGH WISCONSIN AND...BASED ON LOCAL MESOANALYSIS GRAPHICS...THERE IS PLENTY OF LOW AND MID LEVEL INSTABILITY ALREADY IN PLACE. THERE WERE SOME MVFR CIGS IN THE VICINITY OF THE APPROACHING COLD FRONT SO THINK CIGS WILL BECOME MVFR OR AT LEAST BELOW 5KFT AHEAD OF THE STORMS. MVFR...AND SCATTERED IFR...CIGS AND VSBYS CAN BE EXPECTED WITH THE STORMS...ALONG WITH SOME WIND GUSTS IN EXCESS OF 50KTS AND LARGE HAIL. EXPECT RELATIVELY LIGHT WINDS AFTER THE FRONT PASSES. AREAS OF IFR VSBYS IN FOG ARE LIKELY ALONG WITH MVFR CIGS...MAINLY BETWEEN 08Z AND 12Z. CONDITIONS SHOULD BE VFR AFTER THAT. MG && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && MG/TDH
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREEN BAY WI 243 PM CDT MON JUL 30 2012 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-311945- 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- 243 PM CDT MON JUL 30 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST WISCONSIN. .DAY ONE...THE REST OF THIS AFTERNOON AND TONIGHT THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EARLY TONIGHT. WIND GUSTS IN EXCESS OF 60 MPH AND LARGE HAIL ARE THE PRIMARY THREATS WITH THE STORMS THROUGH 8 PM TONIGHT. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH MONDAY THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY NIGHT INTO THURSDAY... AND AGAIN FRIDAY NIGHT INTO SATURDAY. THE THUNDERSTORMS AT THE END OF THE WEEK COULD BECOME SEVERE IF THE SYSTEM RESPONSIBLE FOR THEM COMES THROUGH DURING PEAK HEATING. LARGE HAIL AND DAMAGING WINDS WOULD BE THE PRIMARY THREATS. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF THUNDERSTORM WIND GUSTS OVER 50 MPH OR LARGE HAIL TO THE NATIONAL WEATHER SERVICE. LMZ521-522-541>543-311945- THE BAY OF GREEN BAY SOUTH OF A LINE FROM CEDAR RIVER MI TO ROCK ISLAND PASSAGE-LAKE MICHIGAN FROM WASHINGTON ISLAND TO SHEBOYGAN- 243 PM CDT MON JUL 30 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST LAKE MICHIGAN AND THE WATERS OF GREEN BAY. .DAY ONE...TONIGHT THUNDERSTORMS CAN BE EXPECTED LATE THIS AFTERNOON INTO TONIGHT. A FEW OF THESE STORMS COULD BECOME SEVERE WITH STRONG GUSTY WINDS AND LARGE HAIL. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH MONDAY THUNDERSTORMS ARE ALSO POSSIBLE WEDNESDAY NIGHT INTO THURSDAY...AND AGAIN FRIDAY NIGHT INTO SATURDAY. THERE IS A CHANCE THAT SOME OF THE STORMS FRIDAY NIGHT INTO SATURDAY COULD BECOME SEVERE WITH LARGE HAIL AND DAMAGING WINDS.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREEN BAY WI 403 PM CDT MON JUL 30 2012 WIZ012-013-302200- FLORENCE-NORTHERN MARINETTE COUNTY- 403 PM CDT MON JUL 30 2012 ...THUNDERSTORMS DEVELOPING WEST AND SOUTHWEST OF IRON MOUNTAIN... AT 400 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A CLUSTER OF DEVELOPING THUNDERSTORMS OVER FLORENCE AND NORTHERN MARINETTE COUNTIES...MOVING EAST AT 30 MPH. UP TO ONE HALF INCH DIAMETER HAIL...WINDS GUSTS TO 30 TO 40 MPH AND BRIEF HEAVY DOWNPOURS WILL BE POSSIBLE WITH THESE STORMS. * THE THUNDERSTORM WILL BE NEAR... PEMBINE BY 440 PM CDT... GUSTY WINDS MAY CAUSE LIGHT WEIGHT OBJECTS TO BE BLOWN OVER. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED. TH
The Marquette radar (KMQT), 94 km away, was scanning. The volume nearest the first event began at 21:18 UTC.
18 hail, 1 thunderstorm wind. Local standard time, as filed.
Quarter size hail fell near Niagara though most of the hailstones were pea to marble size.
Nickel size hail fell near Bear Creek.
Hail to 2 inches in diameter fell west of Sobieski.
Quarter size hail fell west of Green Bay, near Howard.
Quarter size hail fell in Little Suamico.
Walnut size hail fell in Green Bay.
Hail reached the size of tennis balls west of Green Bay in the village of Howard. Several homes and cars sustained minor damage from the large hail.
Quarter size hail fell south of Suamico.
Penny size hail fell in Bellevue.
Quarter size hail fell southeast of Pilsen.
Quarter size hail fell for 2 minutes in Wrightstown.
Penny size hail fell in Morrison.
Golf ball size hail fell in Greenleaf, cracking the windshield of at least one vehicle.
Nickel size hail fell at Peninsula State Park.
Quarter size hail fell at Fish Creek.
Large hail, at least 2 inches in diameter, fell in Maribel.
Penny size hail fell at Egg Harbor.
Quarter size hail fell at Egg Harbor.
Thunderstorm winds blew down trees near the Lake Michigan shore on Country Road V a few miles north of Two Rivers.
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, July 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: 402270, 402271, 402272, 402274, 402275, 402276, 402279, 402280, 402282, 402284, 402285, 402286, 402287, 402288, 402289, 402291, 402293, 402294, 402295.