Thunderstorms that moved across northern Wisconsin produced isolated large hail. The storms also caused lightning damage in Oconto 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 GRB wrote it up.
Thunderstorms that moved across northern Wisconsin produced isolated large hail. The storms also caused lightning damage in Oconto County.
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 May 9, 2:24 PM CST, 10 hours 6 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 324 PM CDT MON MAY 9 2011 .SYNOPSIS...A RETURN TO WET AND RELATIVELY COOL WX. UPR FLOW ACRS THE CONUS AND SRN CANADA WL AMPLIFY INTO FULL BLOWN BLOCKING REGIME BY THE WEEKEND...WITH SOME SLOW PROGRESSION LIKELY RETURNING EARLY NEXT WK. SLOW MOVG UPR TROF WL GET LOCKED-IN NR THE AREA AS THE BLOCK EVOLVES...LIKELY RESULTING IN A PROLONGED WET PERIOD. THE CLDS AND PCPN WL KEEP AFTN TEMPS BLO NORMAL ON MOST DAYS. && .SHORT TERM...TONIGHT INTO TUESDAY...MAIN FCST CONCERNS ARE VERY SHORT-TERM WAKE LOW WIND THREAT...THEN PCPN TRENDS AND TEMPERATURES. IMPRESSIVE WAKE LOW HAS PUSHED THROUGH C/NC WI THIS AFTERNOON... WITH PEAK GUSTS TO 45 KTS AT MFI AND 53 KTS AT AUW. THERE HAVE BEEN SOME REPORTS OF TREES AND POWER LINES DOWN IN WAUSAU/MOSINEE. MOST OTHER OBS SITES HAVE SHOWN GUSTS IN THE 30-40 KT RANGE. EXPECT THIS FEATURE TO CONTINUE TO SHIFT EAST OVER THE NEXT 2 TO 3 HOURS... AND PRODUCE GUSTY...BUT HOPEFULLY NOT DAMAGING...WINDS. BEST BET FOR REALLY STRONG GUSTS (BASED ON RECENT REPORTS...THE PRESSURE RISE/FALL COUPLET AND RADAR TRENDS) APPEARS TO BE FROM ANTIGO TO WAUPACA...EASTWARD TO MARINETTE AND THE NORTHERN FOX VALLEY. HAVE GONE WITH LIKELY POPS OVER THE ENTIRE CWA THIS EVG...AS THE H8 WARM FRONT AND ASSOCIATED ELEVATED INSTABILITY SURGES NORTH ACROSS THE AREA. SOME OF THIS ACTIVITY IS ALREADY DEVELOPING OVER WEST CENTRAL WI. WILL CONTINUE WITH A DECREASING TREND IN POPS FROM SW TO NE OVERNIGHT. MODELS ALL SUPPORT LOW CLOUDS ADVECTING INTO THE REGION OVERNIGHT. TEMPS ARE A TOUGH CALL...AS AFTERNOON SHOWERS/TSTMS HAVE CAUSED TEMPS TO DROP INTO THE LOWER TO MID 50S OVER THE SW HALF OF THE FA...AND THERE IS SOME CONCERN AS TO HOW MUCH RECOVERY WILL OCCUR DURING THE LATE AFTERNOON. REGARDLESS... GENERALLY STAYED CLOSE TO MAV/CONSMOS GUIDANCE...WITH LOWS IN THE MID 40S TO LOWER 50S. WITH AN UPPER LEVEL RIDGE EXPECTED TO BUILD OVER WI ON TUESDAY... AND VERY WARM H7 TEMPS ADVECTING INTO THE RGN DURING THE AFTERNOON... EXPECT A GENERAL LULL IN PCPN COVERAGE. HAVE KEPT SLGT CHC POPS OVER MOST OF THE FA...BUT RAISED POPS BACK INTO THE CHC CATEGORY FOR NC WI...WHERE H8 MOISTURE CONVERGENCE IS MAXIMIZED LATE IN THE DAY. LOW CLOUDS WILL LIKELY PERSIST FOR MUCH OF THE DAY...WHICH WILL LIMIT DAYTIME HEATING. SHALLOW MIXING AND CLOUDS WILL LIKELY KEEP MOST OF THE AREA IN THE 60S...WITH PERHAPS SOME LOWER 70S OVER OUR SW COUNTIES. .LONG TERM...TUE NGT THROUGH NEXT MON. TOUGH TO ADD MUCH IN THE WAY OF SPECIFICS TO THE FORECAST. INITIAL SHRTWV WL CONT TO LIFT NWD OUT OF THE PLAINS TROF TUE NGT/WED...RESULTING IN LEAD CYCLONE LIFTG NWD WELL TO OUR W. SYSTEM TRACKING SO FAR W WL HAVE A HARD TIME DRIVING THE WARM FRONT NWD ACRS THE AREA...AND SHOULD RESULT IN PERSISTENT ELY COMPONENT TO THE WIND...ESP NEAR THE LAKE. ACCORDINGLY...ADJUSTED MAX TEMPS DOWN SIGNIFICANTLY AT THE LAKESHORE. MODELS NOT CLEAR ON THE DETAILS OF THE PATTERN AFTER THAT...AND OFFERED VARYING IDEAS ON HOW SFC PATTERN WL EVOLVE. ALOFT HOWEVER...IT IS LIKELY THAT UPR LOW WL GRADUALLY CONSOLIDATE AND WORK EWD FM THE PLAINS. IT IS LIKELY TO PASS S OF THE AREA LATE THIS WK OR EARLY IN THE WEEKEND. HARD TO GET A HANDLE ON WHEN TO GO WITH HIGHEST POPS. FOR NOW...OPTED TO KEEP POPS IN HIGH-END CHC CATEGORY FOR MOST OF THE TIME. AT LEAST SOME FCST PERIODS WL EVENTUALLY NEED TO BE TAKEN UP TO LIKELY/CATEGORICAL ONCE THE SPECIFICS OF THE FORECAST BECOME CLEARER. PCPN TOTALS FOR THE PERIOD WL PROBABLY END UP WELL ABV NORMAL...BUT AT THIS POINT IT APPEARS PCPN WL BE SPREAD OUT OVER A LONG ENOUGH PERIOD TO HELP MITIGATE HYDRO CONCERNS. WL LIKELY END UP WITH DENSE FOG OVER THE LAKE AND ALONG THE LAKESHORE AT SOME POINT LATER THIS WK. BUT AT THIS POINT IT SEEMED SUFFICIENT TO JUST HAVE AREAS OF FOG OVER THE WATER AND ALONG THE LAKESHORE. PCPN CHC COULD CONCEIVABLY LINGER RIGHT THROUGH THE END OF THE FCST PERIOD. BUT AT THIS POINT...CHC THE LAST DAY OR SO OF THE PERIOD SEEMED LOW ENOUGH TO JUST GO DRY FOR NOW. && .AVIATION...STRONG WAKE LOW WINDS WILL AFFECT ATW/GRB BETWEEN 2030Z-22Z...WITH GUSTS TO 40 KTS POSSIBLE. THE INITIAL TSTM COMPLEX WILL SHIFT EAST LATE THIS AFTERNOON...BUT MORE SHOWERS AND TSTMS WILL DEVELOP DURING THE LATE AFTERNOON AND EVENING AS A 850 MB WARM FRONT LIFTS NORTH INTO THE REGION. MVFR CONDITIONS ARE LIKELY WITH ANY TSTMS. LOW CLOUDS SHOULD SPREAD INTO THE AREA DURING THE OVERNIGHT HOURS...AND LINGER INTO TUESDAY. MOST OF THE CIGS SHOULD BE IN THE MVFR CATEGORY. LLWS IS EXPECT TO DEVELOP EARLY THIS EVENING...AND CONTINUE UNTIL 10Z-12Z/TUES. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && KIECKBUSCH/SKOWRONSKI
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREEN BAY WI 346 PM CDT MON MAY 9 2011 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-102100- 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- 346 PM CDT MON MAY 9 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST WISCONSIN. .DAY ONE...TONIGHT THERE IS A CHANCE OF THUNDERSTORMS ACROSS THE ENTIRE FORECAST TONIGHT. ISOLATED STRONG THUNDERSTORMS WITH HAIL CAN BE EXPECTED...BUT WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH MONDAY SCATTERED THUNDERSTORMS WILL AFFECT THE AREA AT TIMES FROM TUESDAY THROUGH FRIDAY. SOME OF THE STORMS COULD PRODUCE HAIL AND HEAVY RAIN. ALTHOUGH SEVERE WEATHER CANNOT BE RULED OUT...THE GREATEST RISK OF SEVERE WEATHER IS EXPECTED TO BE SOUTH OF THE AREA. .SPOTTER INFORMATION STATEMENT... SPOTTER GROUP ACTIVATION SHOULD NOT BE NEEDED TONIGHT...BUT SPOTTERS ARE STILL URGED TO RELAY ANY REPORTS OF HAIL OR WIND GUSTS OF 40 MPH OR HIGHER. LMZ521-522-541>543-102100- THE BAY OF GREEN BAY SOUTH OF A LINE FROM CEDAR RIVER MI TO ROCK ISLAND PASSAGE-LAKE MICHIGAN FROM WASHINGTON ISLAND TO SHEBOYGAN- 346 PM CDT MON MAY 9 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST LAKE MICHIGAN AND THE WATERS OF GREEN BAY. .DAY ONE...TONIGHT THUNDERSTORMS TONIGHT MAY PRODUCE BRIEF GUSTY WINDS WHICH COULD BE HAZARDOUS TO BOATERS. HOWEVER...WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH MONDAY THERE IS A CHANCE OF THUNDERSTORMS FROM TUESDAY THROUGH FRIDAY. THE STRONGEST STORMS WILL PRODUCE HAIL AND HEAVY RAIN. DENSE FOG IS ALSO POSSIBLE AT TIMES. TK/JS
The Green Bay radar (KGRB), 81 km away, was scanning. The volume nearest the first event began at 06:32 UTC.
1 hail, 1 lightning. Local standard time, as filed.
Thunderstorms produced quarter size hail as they passed through Mountain. Time of the event was estimated.
Lightning struck a pair of 138 kilovolt transmission lines near Crivitz. The power lines run from the Oconto Falls area to Kingsford, Michigan. The loss of the two lines, combined with a third line that was out of service for maintenance, resulted in a blackout for about 75,000 customers in the western half of Upper Michigan. Several school districts had to cancel classes due to the lack of electricity. The time of the lightning strike and associated damage in Wisconsin are estimates.
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: 310077, 310081.