Thunderstorms developed ahead of a cold front during the afternoon hours. The strongest storms produced damaging winds and large hail across central and east-central Wisconsin.
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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.
Thunderstorms developed ahead of a cold front during the afternoon hours. The strongest storms produced damaging winds and large hail across central and east-central Wisconsin.
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 31, 1:21 PM CST, 1 hour 7 minutes earlier.
Area Forecast Discussion National Weather Service Green Bay WI 221 PM CDT Sat Jul 31 2021 Forecast discussion for routine afternoon forecast issuance .SHORT TERM...Tonight and Sunday Issued at 221 PM CDT Sat Jul 31 2021 The main forecast concern to be on evening thunderstorms, with secondary concerns on potential for afternoon showers to pop up Sunday afternoon. The 19Z MSAS surface analysis indicated a cold front that extended roughly from Marinette west-southwest to just north of Wausau to just south of Eau Claire. Showers and thunderstorms had developed over central WI ahead of the front, but so far have behaved themselves with brief heavy rainfall and some cloud-to-ground lightning. Visible satellite imagery showed some taller cumulus clouds behind the front, so cannot rule out additional showers to develop late this afternoon. Finally, an area of high pressure was situated over the northern Plains. Look for showers and thunderstorms to continue to drop south- southeast through the rest of central and east-central WI late this afternoon into the early evening. Once the front exits the region, dry conditions are forecast with clearing skies as the high pressure begins to build east across the Upper MS Valley. Satellite imagery does show a lot of smoke from western wildfires, thus will need to mention (continue) the hazy conditions. Min temperatures to range from the upper 40s to lower 50s north, middle to upper 50s south. The high pressure is forecast to reach the western Great Lakes region Sunday afternoon and provide for mostly sunny to partly cloudy skies and less humidity as dew points drop back into the 50s. Gusty northerly winds will allow usher in a cooler air mass into WI with max temperatures in the upper 60s to around 70 degrees north, lower to middle 70s south. The only fly in the ointment would be if another shortwave trough moving south could develop a few showers. For now, based on a lack of moisture, have kept Sunday dry. .LONG TERM...Sunday Night Through Saturday Issued at 221 PM CDT Sat Jul 31 2021 Fairly quiet weather expected through much of the extended portion of the forecast with a gradual warming trend. Sunday night through Monday night: A dry surface ridge is expected to build across the area through this time period, bring precipitation-free conditions along with mostly clear skies. The one exception could be early Monday evening into Monday night as a shortwave approaches/passes through the area with perhaps an increase in mid-level moisture. Instability is expected to be around 500 J/kg. Not expecting anything severe, but thunderstorms will be possible. Otherwise, temperatures are expected to be near normal. Overnight lows will be in the upper 40s to mid 50s. Highs will warm into the mid to upper 70s to around 80. Tuesday through Wednesday: The EC/GFS are hinting at a surface boundary sinking southward into the area Tuesday into Tuesday night, which may lead to some afternoon showers and thunderstorms. This would mainly be during peak heating into the early evening hours before diminishing overnight. In fact, models are painting out around 1000-1500 J/kg of MUCAPE, but shear values are only around 15- 20 kts. This would allow for strong storms, but a relatively low threat of severe from pulse-type storms. Behind the front, drier air is expected to arrive, bringing fairly quiet conditions for Wednesday. High temperatures will warm into the low to mid 80s with overnight lows in the 50s. Rest of the extended: Model solutions differ on exact timing and placement of features beyond Wednesday; however, there is some agreement that the next system will approach the area toward next weekend (Saturday). At this point will stick with a blend of the model guidance for the Wednesday night through Saturday time period. Temperatures are expected to warm above normal. && .AVIATION...for 18Z TAF Issuance Issued at 1247 PM CDT Sat Jul 31 2021 Pesky IFR ceilings eroded during the morning hours, leaving high- end MVFR and VFR conditions by the noon hour. A mix of daytime cu and some mid-level clouds will continue through the early evening hours. A broken line of showers and storms is expected to move north to south across the area this afternoon and evening ahead of a cold front. Will continue with the TEMPO groups to highlight the most likely two-three hour window for each site. Storms have developed a little ahead of schedule, so will bump up the timing. Brief lower CIGs/VSBYs will be possible in the stronger storms. Once the showers and storms exit this afternoon/evening, dry conditions are expected the rest of the night. Some patchy fog is possible overnight, but confidence not high enough to include at this time. Mainly dry conditions are expected on Sunday, but a late morning or afternoon light shower or sprinkle is possible as a low-end VFR cloud deck forms. Smoke continues to spread across the area providing for a very hazy sky and reducing VSBYs mainly to between 3SM to 6SM. Expect this to continue through at least sunset and possibly through the night. HRRR showing the bulk of the smoke exiting the area overnight, so will not include any reduced VSBYs on Sunday. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM.....Kallas LONG TERM......Cooley AVIATION.......Bersch
Hazardous Weather Outlook National Weather Service Green Bay WI 224 PM CDT Sat Jul 31 2021 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-011930- Vilas-Oneida-Forest-Florence-Northern Marinette County-Lincoln- Langlade-Menominee-Northern Oconto County-Door-Marathon-Shawano- Wood-Portage-Waupaca-Outagamie-Brown-Kewaunee-Waushara-Winnebago- Calumet-Manitowoc-Southern Marinette County- Southern Oconto County- 224 PM CDT Sat Jul 31 2021 This Hazardous Weather Outlook is for north-central and northeast Wisconsin. .DAY ONE...Tonight Scattered thunderstorms are expected mainly south of a line from Marshfield to Green Bay early this evening. A few storms may be capable of producing large hail or damaging winds through early evening. There is a Marginal Risk of severe storms for much of northeast Wisconsin. Widespread smoke will reduce visibilities and air quality through tonight. .DAYS TWO THROUGH SEVEN...Sunday through Saturday There is a chance of thunderstorms on Tuesday afternoon. A few storms may become strong and produce small hail and heavy rainfall; however, the threat of widespread severe weather is low at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated this evening; however, spotters are encouraged to forward any occurrences of wind gusts greater than 40 mph and hail greater than one-half inch. LMZ521-522-541>543-011930- The Bay of Green Bay south of a line from Cedar River MI to Rock Island Passage-Lake Michigan from Washington Island to Sheboygan- 224 PM CDT Sat Jul 31 2021 This Hazardous Weather Outlook is for portions of northwest Lake Michigan and the waters of Green Bay. .DAY ONE...Tonight There is a chance of thunderstorms through early evening. Any thunderstorms will pose a hazard to mariners. Gusty north winds and building waves could create conditions hazardous to small craft late tonight. .DAYS TWO THROUGH SEVEN...Sunday through Saturday Gusty north winds and building waves could create conditions hazardous to small craft Sunday. There is a chance of thunderstorms Tuesday afternoon. Kallas/Cooley
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREEN BAY WI
307 PM CDT SAT JUL 31 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0257 PM TSTM WND GST WISCONSIN RAPIDS 44.40N 89.84W
07/31/2021 M55.00 MPH WOOD WI ASOS
AT THE AIRPORT.
&&
SACSpecial Weather Statement
National Weather Service Green Bay WI
307 PM CDT Sat Jul 31 2021
WIZ035-036-045-312100-
Wood WI-Waushara WI-Portage WI-
307 PM CDT Sat Jul 31 2021
...STRONG THUNDERSTORMS MOVING THROUGH CENTRAL WISCONSIN...
At 306 PM CDT, Doppler radar was tracking a strong thunderstorm near
Lake Wazeecha, or 8 miles south of Wisconsin Rapids, moving southeast
at 25 mph.
Pea size hail and winds in excess of 40 mph will be possible with
this storm.
Locations impacted include...
Wautoma, Plainfield, Nekoosa, Port Edwards, Dakota, Richford, Coloma,
Almond, Hancock and Kellner.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
&&
LAT...LON 4440 8949 4398 8921 4398 8960 4425 8960
4425 9022 4426 9024
TIME...MOT...LOC 2006Z 333DEG 21KT 4428 8977
KallasThe Green Bay radar (KGRB), 7 km away, was scanning. The volume nearest the first event began at 20:29 UTC.
2 hail, 1 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds downed multiple large tree branches and power lines on the northwest side of Green Bay. The time of this event is an estimate based on radar data.
Half dollar size hail fell southeast of Athens.
Penny size hail fell in Kronenwetter.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2021Every state in 2021This day in weather historyWarnings in Wisconsin, July 2021
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: 964255, 968190, 964254.