Tornadoes · United States · Wisconsin · 2021
EF0 tornado, Grellton to Sullivan, Wisconsin, July 29, 2021
From Grellton to Sullivan, this EF0 tornado ran 3.6 miles across Jefferson County on July 29, 2021, touching down at 1:07 AM CDT and reaching 25 yards wide. It killed nobody.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
EF2111 to 135 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
EF3136 to 165 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
EF5over 200 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unrated
The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.
The record
- Rating
- EF0
- Date
- July 29, 2021
- Touchdown
- 1:07 AM CDT (06:07 UTC)
- Lifted
- 1:12 AM CDT (06:12 UTC)
- On the ground
- 5 minutes
- Path length
- 3.6 miles (5.8 km)
- Path width
- 25 yards (23 m)
- Deaths
- 0
- Injuries
- 0
- County
- Jefferson County
- Touchdown point
- 43.115, -88.744
- Lift-off point
- 43.080, -88.692
- Record number
- 2107290007-01
The damage survey
99 damage points were recorded along this path by NWS MKX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 110 mph.
- North side Basement blew in as well.
- Edge of corn crop pushed down in multiple directions.
- Metal sheeting wrapped around downed power pole.
- Two garages and one large horse barn collapsed. Debris throw into field to the SSE. Garage was bolted into foundation, but wood was rotten.
Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.
What the Weather Service recorded
A round of severe storms tracked into southwest Wisconsin during the early morning hours on July 28th. Followed by another round of stronger, more widespread thunderstorms that begin to dive south across central Wisconsin late in the evening on July 28th through the early morning hours on July 29th.
This was 1 of 17 tornadoes to occur in Wisconsin on the night of July 28th into the early morning hours of July 29th. This was the 11th overall tornado for the event. A line of storms developed in northern Wisconsin and pushed south into southern Wisconsin in the overnight hours of the 28th into the 29th of July with mainly brief tornadoes and damaging winds occurring.| |This tornado began to the southwest of Watertown and mainly moved through rural areas to the south of the city. Some of the main damage was to a house/farm near Hilltop Rd and Horseshoe Rd, otherwise it was mainly tree and crop damage. The path cross Highway 26 near Ebenezer Rd and ended near Cattail Dr.
This was 1 of 17 tornadoes to occur in Wisconsin on the night of July 28th into the early morning hours of July 29th. This was the 12th overall tornado for the event. A line of storms developed in northern Wisconsin and pushed south into southern Wisconsin in the overnight hours of the 28th into the 29th of July with mainly brief tornadoes and damaging winds occurring. ||This tornado began near Highway 26 north of I-94 and eventually crossed I-94 near Saucer Dr. Mainly tree damage along this path.
This was 1 of 17 tornadoes to occur in Wisconsin on the night of July 28th into the early morning hours of July 29th. This was the 13th overall tornado for the event. A line of storms developed in northern Wisconsin and pushed south into southern Wisconsin in the overnight hours of the 28th into the 29th of July with mainly brief tornadoes and damaging winds occurring. ||This tornado began a few country blocks east of tornado #12 and started near County Highway P near Aliceton Dr and then tracked to the south, damaging a number of structures along County Rd E, crossing I-94 before going through Concord. The tornado then went through rural areas before ending east of Willow Glen Rd.
This was 1 of 17 tornadoes to occur in Wisconsin on the night of July 28th into the early morning hours of July 29th. This was the 14th overall tornado for the event. A line of storms developed in northern Wisconsin and pushed south into southern Wisconsin in the overnight hours of the 28th into the 29th of July with mainly brief tornadoes and damaging winds occurring. ||This tornado began near Indian Point Rd to the southwest of Golden Lake in the far eastern part of Jefferson county. It crossed the Jefferson/Waukesha County line to the NW of the Bark River. Damage noted in this area by Indian Point Rd was to trees.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
What forecasters said that day
The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Milwaukee, WI wrote its last area forecast discussion before the tornado touched down at Jul 28, 8:50 PM CDT, 4 hours 17 minutes earlier.
Area forecast discussion, Jul 28, 8:50 PM CDT, 4 hours 17 minutes before
Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 850 PM CDT Wed Jul 28 2021 .UPDATE... (Issued 849 PM CDT Wed Jul 28 2021) Storms have started over northern WI/central MN this evening along the warm front and weak lake breeze boundary off of Lake Superior. The 00z MPX sounding is quite unstable with 4,000-6,000 J/kg much of this is due to steeper mid/upper level lapse rates. The surface lapse rates remain weak due to remnant cloud cover and smoke layer which likely limited some heating/mixing this afternoon. But as the LLJ gets going and bulk shear ramps up expect any storms to quickly become severe. Hodographs showed strong turning in the low levels with the MPX sounding and this is also evident in the VWP hodograph from the ARX radar. As the LLJ intensifies tonight we can potentially expect a similar looking hodograph for our area ahead of the storms arriving. While all modes of severe are possible as storms congeal into a line and drop south, the greatest threat is going to be with strong damaging winds of 70 to 90+ mph. In addition to that if we do end up with a similar looking hodograph we could see a few embedded tornadoes in the line. The threat area is for the entire area especially since storms are developing a little further to the west than forecast. Made some minor tweaks to the timing of storms but otherwise the forecast is in good shape. Stumpf && .SHORT TERM... (Issued 130 PM CDT Wed Jul 28 2021) Tonight: Main focus continues to be on anticipated severe convective system rolling through here later this evening. Think as storms transition from more discrete/supercellular to our north and congeal to a line structure closer to central WI that the line will really gain speed and roll through southern WI, esp EC and SE WI in fairly short order. Potential is fairly high this will bow out with winds in excess of 70 and perhaps a few QLCS type tornadoes as well. So the heightened moderate from SPC looks on track. Decent upper level jet divergence, a mid level shortwave and plenty of higher CAPE values into the late evening/early overnight, the environment appears primed to support the arriving storms. Thursday through Thursday night: Cool advection and high pressure take hold. Winds will be predominantly from the north and northeast. Expecting some lower cloud cover to linger especially for the morning but with a low level thermal trough the clouds may be a bit more stubborn. && .LONG TERM... (Issued 130 PM CDT Wed Jul 28 2021) Friday through Friday night: High pressure remains in control into Friday though shifts off to the southeast and begins a waa regime. Saturday through Saturday night: A northwest mid level flow will drop in a some mid level energy with an associated low pressure system and cold front. Progs are in pretty good agreement in developing some shra/tsra with these features that could linger into the evening hours. Sunday through Wednesday: High pressure will largely dominate this period. There is some hint of some diurnal activity with any mid level troughing that may swing through, especially Monday into Monday evening. So some precip potential may need to be added to the forecast at some point. For now will stick with the blended guid and leave this mention out for now. && .AVIATION... (Issued 849 PM CDT Wed Jul 28 2021) Initially VFR conditions are forecast this evening but a strong line of thunderstorms is expected to drop south out of north- central WI. These will bring strong gusty winds, heavy downpours, frequent cloud to ground lightning, and IFR/MVFR cigs. Once storms move through expect some improvement in cigs/vsbys through the morning as drier air starts to filter in from the north. A few areas of MVFR cigs are possible Thursday afternoon for locations closer to the lake as a front rolls down Lake Michigan. Stumpf && .MARINE... (Issued 130 PM CDT Wed Jul 28 2021) A complex of strong to severe thunderstorms is expected to track across northern Wisconsin late this afternoon and then drop into central and southern Wisconsin and Lake Michigan this evening. It should exit southern Lake Michigan by 4 AM. Persistent northerly winds on Thursday will build higher waves over the south half of Lake Michigan Thursday afternoon through Friday. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && Visit us at weather.gov/milwaukee Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSMilwaukee www.twitter.com/NWSMilwaukee www.youtube.com/NWSMilwaukee
Hazardous weather outlook, Jul 28, 9:04 PM CDT, 4 hours 3 minutes before
Hazardous Weather Outlook National Weather Service Milwaukee/Sullivan WI 904 PM CDT Wed Jul 28 2021 WIZ046-047-051-052-056>060-062>072-300215- Marquette-Green Lake-Fond du Lac-Sheboygan-Sauk-Columbia-Dodge- Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee- Lafayette-Green-Rock-Walworth-Racine-Kenosha- 904 PM CDT Wed Jul 28 2021 This Hazardous Weather Outlook is for portions of east central Wisconsin, south central Wisconsin and southeast Wisconsin. .DAY ONE...Tonight A complex of thunderstorms will move southward into southern Wisconsin this evening into the overnight hours. Severe thunderstorms are expected with damaging winds as the main concern. Large hail and a tornado are possible as well. A Particularly Dangerous Situation Severe Thunderstorm Watch has been issued until 2 AM for all of southern Wisconsin. An Air Quality Advisory for Ozone is in effect for Kenosha, Racine, Milwaukee, Ozaukee, and Sheboygan counties until 11 pm CDT. .DAYS TWO THROUGH SEVEN...Thursday through Wednesday There is a chance of thunderstorms Saturday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Spotters are requested to report peak wind gusts and any damage observed to the national weather service at milwaukee/sullivan. LMZ643>646-300215- Sheboygan to Port Washington WI- Port Washington to North Point Light WI- North Point Light to Wind Point WI- Wind Point WI to Winthrop Harbor IL- 904 PM CDT Wed Jul 28 2021 This Hazardous Weather Outlook is for the nearshore waters from Sheboygan Wisconsin to Winthrop Harbor Illinois. .DAY ONE...Tonight A complex of thunderstorms will move southward into southern Wisconsin this evening into the overnight hours. Severe thunderstorms are expected with damaging winds as the main concern. Large hail and a tornado are possible as well. A Particularly Dangerous Situation Severe Thunderstorm Watch has been issued until 2 AM for all of the nearshore waters. .DAYS TWO THROUGH SEVEN...Thursday through Wednesday There is a chance of thunderstorms Saturday afternoon and evening. LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868- 870-872-874-876-878-300215- Lake Michigan Michigan City IN to St. Joseph MI 5 NM offshore to mid-line of lake.- Lake Michigan from Seul Choix Point to Rock Island Passage 5NM offshore to Mid Lake- Lake Michigan South of a line from Seul Choix Point to the Mackinac Bridge and North of a line from Charlevoix MI to South Fox Island 5NM offshore- Lake Michigan from Charlevoix to Point Betsie MI 5NM Offshore to mid lake- Lake Michigan from Point Betsie to Manistee MI 5NM offshore to Mid Lake- Lake Michigan from Rock Island Passage to Sturgeon Bay WI 5NM offshore to mid lake- Lake Michigan from Sturgeon Bay to Two Rivers WI 5NM offshore to Mid Lake- Lake Michigan from Two Rivers to Sheboygan WI 5NM offshore to Mid Lake- Lake Michigan from Sheboygan to Port Washington WI 5NM offshore to Mid Lake- Lake Michigan from Port Washington to North Point Light WI 5NM offshore to Mid Lake- Lake Michigan from North Point Light to Wind Point WI 5NM offshore to Mid Lake- Lake Michigan from Wind Point WI to Winthrop Harbor IL 5NM offshore to Mid Lake- Lake Michigan from Winthrop Harbor to Wilmette Harbor IL 5NM offshore to Mid Lake- Lake Michigan from Wilmette Harbor to Michigan City in 5NM offshore to Mid Lake- Lake Michigan from Pentwater to Manistee MI 5NM offshore to Mid Lake- Lake Michigan from Whitehall to Pentwater MI 5NM offshore to Mid Lake- Lake Michigan from Grand Haven to Whitehall MI 5NM offshore to Mid Lake- Lake Michigan from Holland to Grand Haven MI 5NM offshore to Mid Lake- Lake Michigan from South Haven to Holland MI 5NM offshore to Mid lake- Lake Michigan from St Joseph to South Haven MI 5NM offshore to Mid Lake- 904 PM CDT Wed Jul 28 2021 This Hazardous Weather Outlook is for the open waters of Lake Michigan. .DAY ONE...Tonight A complex of thunderstorms will move southward into southern Wisconsin this evening into the overnight hours. Severe thunderstorms are expected with damaging winds as the main concern. Large hail and a tornado are possible as well. A Particularly Dangerous Situation Severe Thunderstorm Watch has been issued until 2 AM for the western open waters of Lake Michigan at this time. This could be expanded eastward overnight. .DAYS TWO THROUGH SEVEN...Thursday through Wednesday There is a chance of thunderstorms Saturday into Saturday evening. www.weather.gov/mkx
In the hours before
Special weather statement, Jul 28, 11:48 PM CDT, 1 hour 19 minutes before
Special Weather Statement
National Weather Service Milwaukee/Sullivan WI
1148 PM CDT Wed Jul 28 2021
WIZ056-057-290530-
Columbia-Sauk-
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT WESTERN COLUMBIA AND
SAUK COUNTIES...
At 1147 PM CDT, radar indicated strong thunderstorms were located
along a line extending from 8 miles southwest of Westfield to near
Reedsburg to near Westby. Movement was south at 50 mph.
Winds of 40 to 50 mph are possible with these storms.
Locations impacted include...
Baraboo, Portage, Reedsburg, Prairie Du Sac, Sauk City, Wisconsin
Dells, Lake Wisconsin, Lodi, Lake Delton, Poynette, Spring Green,
West Baraboo, Plain, Bluffview, North Freedom, Merrimac, La Valle,
Rock Springs, Loganville and Ironton.
If outdoors, consider seeking shelter inside a building.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4364 8945 4337 8936 4329 8954 4329 8971
4326 8974 4324 8980 4319 8986 4319 8992
4320 8999 4316 9005 4315 9005 4316 9009
4316 9018 4317 9019 4355 9019 4356 9031
4364 9031
TIME...MOT...LOC 0447Z 353DEG 43KT 4379 8961 4361 9004 4364 9078
HANSENLocal storm report, Jul 29, 12:08 AM CDT, 59 minutes before
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</html>Local storm report, Jul 29, 12:51 AM CDT, 16 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1251 AM CDT THU JUL 29 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1245 AM TSTM WND GST 7 WNW SPRING GREEN 43.21N 90.19W
07/29/2021 M68 MPH SAUK WI ASOS
THE LONE ROCK ASOS REPORTED A 59 KT GUST.
&&
TPThe air that afternoon
The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.
Green Bay/Straub, WI (KGRB), 00:00Z
6.1 hours before the tornado, 161 km from the path. July 29, 2021.
- Mixed-layer CAPE
- 593 J/kg
- Mixed-layer CIN
- -264 J/kg
- Surface CAPE
- 1038 J/kg
- Mixed-layer LCL
- 1088 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 62 m²/s²
- 0-3 km storm-relative helicity
- 154 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
- 0-3 km lapse rate
- 5.0 K/km
The surface observations
Watertown (RYV), 8 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 00:00 UTC |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Milwaukee radar (KMKX), 20 km away, was scanning. The volume nearest the touchdown began at 06:07 UTC.
Open the radar archive at this moment, over the track
Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.
This ground now
The live radar over the trackEvery 2021 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are
The other tornadoes of July 29, 2021
36 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| July 29 | 1:05 AM CDT | EF0 | Jefferson, WI | 6.0 | 100 | |||
| July 29 | 1:07 AM CDT | EF1 | Jefferson, WI | 7.7 | 200 | |||
| July 29 | 1:23 AM CDT | EF1 | Jefferson, WI | 4.7 | 150 | |||
| July 29 | 1:26 AM CDT | EF1 | Waukesha, WI | 1.0 | 75 | |||
| July 29 | 1:32 AM CDT | EF0 | Waukesha, WI | 2.4 | 50 | |||
| July 29 | 1:38 AM CDT | EF1 | Waukesha, WI | 0.9 | 95 | |||
| July 29 | 12:40 PM EDT | EF0 | Crawford, PA | 0.6 | 75 | |||
| July 29 | 12:55 PM EDT | EF0 | Venango, PA | 0.3 | 15 | $15,000 | ||
| July 29 | 1:54 PM EDT | EF1 | Westmoreland, PA | 4.9 | 100 | $275,000 | ||
| July 29 | 2:25 PM EDT | EF1 | Somerset, PA | 0.2 | 65 | |||
| July 29 | 4:04 PM EDT | EF1 | Lehigh, PA | 2.9 | 90 | |||
| July 29 | 4:25 PM EDT | EF1 | Lehigh, PA | 1.1 | 75 | |||
| July 29 | 4:50 PM EDT | EF2 | Harrison, OH | 2.7 | 220 | $200,000 | ||
| July 29 | 4:59 PM EDT | EF2 | Carroll, OH | 6.2 | 150 | $500,000 | ||
| July 29 | 5:07 PM EDT | EF0 | Howard, MD | 0.3 | 50 | $50,000 | ||
| July 29 | 5:15 PM EDT | EF1 | Jefferson, OH | 2.2 | 300 | $250,000 | ||
| July 29 | 5:16 PM EDT | EF0 | Washington, OH | 0.1 | 55 | $500 | ||
| July 29 | 5:20 PM EDT | EF0 | Indiana, PA | 0.1 | 10 | $50,000 | ||
| July 29 | 5:20 PM EDT | EF0 | Pickaway, OH | 0.9 | 50 | $100,000 | ||
| July 29 | 5:34 PM EDT | EF0 | Lebanon, PA | 0.7 | 60 | |||
| July 29 | 5:40 PM EDT | EF1 | Bucks, PA | 2.7 | 70 | |||
| July 29 | 5:45 PM EDT | EF1 | Jefferson, OH | 2.3 | 300 | $250,000 | ||
| July 29 | 5:54 PM EDT | EF0 | Essex, NJ | 0.3 | 50 | $330,000 | ||
| July 29 | 4:59 PM CDT | EF2 | Bucks, PA to NJ | 6.3 | 400 | |||
| July 29 | 6:00 PM EDT | EF1 | Greene, PA | 2.8 | 200 | $100,000 | ||
| July 29 | 6:10 PM EDT | EF0 | Cambria, PA | 0.1 | 15 | |||
| July 29 | 5:40 PM CDT | EF0 | Cumberland, IL | 0.5 | 50 | |||
| July 29 | 6:56 PM EDT | EF1 | Mercer, NJ | 1.6 | 100 | |||
| July 29 | 7:04 PM EDT | EF3 | Bensalem tornado, PA | 3.4 | 530 | |||
| July 29 | 7:07 PM EDT | EF0 | Philadelphia, PA | 0.4 | 40 | |||
| July 29 | 7:58 PM EDT | EF1 | Shelby, IN | 2.5 | 50 | $43,000 | ||
| July 29 | 8:04 PM EDT | EF0 | Ocean, NJ | 0.8 | 80 | |||
| July 29 | 8:14 PM EDT | EF1 | Shelby, IN | 0.7 | 50 | $15,000 | ||
| July 29 | 7:20 PM CDT | EF1 | Crawford, IL | 0.4 | 75 | |||
| July 29 | 8:42 PM EDT | EF1 | Ocean, NJ | 6.5 | 250 | |||
| July 29 | 9:03 PM EDT | EF2 | Ocean, NJ | 4.2 | 75 | 8 |
What this means
Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.