Several lines of strong thunderstorms with gusty winds moved across southern WI ahead of an approaching cold front. Severe winds occurred in a couple locations.
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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 MKX wrote it up.
Several lines of strong thunderstorms with gusty winds moved across southern WI ahead of an approaching cold front. Severe winds occurred in a couple locations.
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 Milwaukee, WI wrote its last area forecast discussion before the first event at Jun 17, 8:49 PM CST, 2 hours 41 minutes earlier.
Area Forecast Discussion...UPDATED National Weather Service Milwaukee/Sullivan WI 949 PM CDT Thu Jun 17 2021 .MESOSCALE DISCUSSION... (Issued 850 PM CDT Thu Jun 17 2021) Challenging forecast for the rest of this evening through the overnight hours. Bottom line (up front) is that convective evolution is underway. CAMs are favoring transition to linear mode and current cell mergers indicate this is on track. Timing is still roughly on track from late evening into the overnight hours. East/southeast movement to the line is on track. The severe wind risk remains. The hail risk is on the low side. Any tornado risk is tied to linear bows to the east, but this too appears to be on the low side. Rain won't be a drought buster, but we'll take what we can get at this point. Initial area of elevated, weak convection has all but dissipated over far southeastern Wisconsin. Over the past couple of hours, more vigorous convection has erupted near the boundary extending from central WI into southern MN. For the most part, this has been discreet with supercellular structures and reports of hail. Over the past 30 minutes, an uptick in coverage has been noted, particularly just north of our outlook area. The main players for tonight have not changed. A subtle shortwave moving east across southern MN into west central WI is noted via water vapor and RAP initializations. Over the next few hours, a southwestern low level jet will increase in intensity to as much as 40kt. This increase in lower level moisture transport is sorely needed as 00z soundings from DVN and GRB showing a rather pronounced plug of dry air below 700mb. The showers over the past few hours did increase our surface dewpoints, but for the time being quality low level moisture is shallow. Unfortunately, shaky confidence in the evolution of this convection this evening hasn't improved. Signs are there that storms exiting southeast MN will meld with ongoing convection in central WI. This evolution will continue over the next few hours. As we see increased low level warm air and moisture advection with the strengthening jet, we should see cold pools congeal and an eventual acceleration of a line of storms to the east southeast late this evening and into the overnight hours. Given the current amount of dry air in the low levels, it's plausible that this system leans toward outflow dominance. That said, will need to keep an eye on any balanced regions of the line that may surge to the east. 0-3km shear on the order of 35 to 40kt support mesovortex development, though for the time being LCLs remain high side. The biggest question is how far to the southwest convection will expand. Right now, the current location of convection would shift our best chances for storms along and northeast of a line from Lone Rock to Janesville. It's possible far southwestern areas struggle, but there is enough potential given outflow and a southwesterly low level jet to force propagation southwestward into Lafayette/Iowa/Green counties. Will also be monitoring for initiation in south central MN that would aid in better chances for storms in our far southwest. Gagan && .SHORT TERM... (Issued 243 PM CDT Thu June 17 2021) Tonight: Instability and moisture is slowly increasing over our area this afternoon. The main area to watch for initial thunderstorm development will be in the area between La Crosse and Minneapolis. There are already a couple storms developing in this area due to the axis of low level frontogenesis and higher instability with MUCAPE around 1500-2000 J/kg. Dew points are also in the low to mid 60s along the frontal boundary in this area as seen in observations. The 850mb low level jet will help feed heat and moisture into this area with discrete cells expected initially and then congealing into a line before shifting southeast into our area. MUCAPE values will be in the 1500-2500 J/kg range with bulk shear around 40 knots. Corfidi vectors will be from the east southeast and that is the direction we'll expect with storms as the line develops it's cold pool. The best timeframe for severe storms will be after 8 PM northwest of Madison and after 11pm southeast of Madison. This timing may change as it is dependent on initial storm development and when the driving cold pool develops. The main concern will be damaging winds with the line of storms, any isolated storm would have the better potential for gusty winds and hail. Looking at 0-3km bulk shear vectors and little 0-3km MLCAPE it doesn't look that favorable for QLCS tornadoes but can't completely rule out any chance for a tornado. Additionally there will be some decent rain rates with thunderstorms with some picking up a good 1-2" with locally higher amounts possible. If storms remain over an area for long enough there could be some minor localized flooding. Thunderstorms will gradually clear late tonight into early Friday morning. Friday through Friday night: The main through axis and cold front will be swinging through Friday evening and overnight. There are some hints that we could see some showers and storms during the afternoon before the front clears the area, but didn't have enough confidence to include in the forecast at this time. It will depend on how fast we can recover from tonight's storms. Otherwise expect another warm and humid day with afternoon temperatures in the 80s to low 90s and dew points in the upper 50s to mid 60s. RAH && .LONG TERM... (Issued 243 PM CDT Thu June 17 2021) Saturday through Thursday: Temperatures slightly cool for Saturday, as surface high pressure moves through and winds stay more northerly. This will be short- lived, as a system develops over the central/northern Plains and lifts into the northern MN on Sunday. Winds increase out of the south, and the heat and humidity return, with highs in the mid to upper 80s. A tropical system moving into the southern US on Saturday will push a good deal of moisture in the Mid-Mississippi Valley region and as the system starts to take shape on Sunday, the stronger southerly winds and increasing LLJ will pull this moisture northward. Sunday could be another chance for more widespread rainfall, with some strong to severe potential as well. There are still enough timing differences in the models to make the forecast uncertain, and this is also backed up by decent spread in the GEFS members. Cooler temps are then expected to start the week, as a broad longwave trough sets up over the Midwest/NE US. A few shortwaves moving through the flow could bring a few chances for rain towards the middle to latter half of the week, as winds start to switch back to the south and better moisture streams back into the area. Highs gradually warm back into the mid 80s by the end of the week. Stumpf && .AVIATION... (Issued 949 PM CDT Thu Jun 17 2021) Current timing of upstream storms indicate storms may reach the northwest forecast area by around 5Z, the Madison area by 6Z, and the Milwaukee area by 7Z. Will continue to monitor upstream conditions and modify timing as needed. Still thinking there will be a severe threat with these storms, with strong winds being the primary concern. Some hail will be possible as well. Storms should wind down in the southeast by late tonight or early morning Fri, with dry weather and clearing skies Friday. VFR conditions will continue into tomorrow night outside of lower visibilites within heavy rainfall. DDV && .MARINE... (Issued 243 PM CDT Thu June 17 2021) Breezy south to southwest winds continue across the lake with more southeasterly winds along the western shore. A line of thunderstorms is expected to move across the lake this evening with the best chances over central and southern portions of the lake. The main concern with these storms will be strong winds and a potential for large hail. Storms are expected to clear Friday morning with another day of southerly winds over the lake. A cold front will push through the region Friday night with winds shifting to the northwest behind the front. RAH && .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 National Weather Service Milwaukee/Sullivan WI 250 PM CDT Thu Jun 17 2021 WIZ046-047-051-052-056>060-062>072-182000- Marquette-Green Lake-Fond du Lac-Sheboygan-Sauk-Columbia-Dodge- Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee- Lafayette-Green-Rock-Walworth-Racine-Kenosha- 250 PM CDT Thu Jun 17 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 is expected to develop and move southeastward through southern Wisconsin this evening and into the overnight hours. The chance for severe storms has increased with the concern for damaging winds and large hail. The overall tornado threat is low. Storms will be capable of heavy rain and may cause some localized flooding. Best to be weather aware this evening and make sure you have a way to get warnings tonight. .DAYS TWO THROUGH SEVEN...Friday through Thursday Small chances for thunderstorms may linger into Friday morning. More chances for thunderstorms returns Sunday into Sunday night. .SPOTTER INFORMATION STATEMENT... Spotter activation will likely be needed this evening into the overnight hours. LMZ643>646-182000- 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- 250 PM CDT Thu Jun 17 2021 This Hazardous Weather Outlook is for the nearshore waters from Sheboygan Wisconsin to Winthrop Harbor Illinois. .DAY ONE...Tonight A complex of thunderstorms is expected to develop and move southeastward through the nearshore waters later this evening and into the overnight hours. Some storms may become severe, with damaging winds the main hazard. Large hail is also possible. Keep up with the forecast for this period. .DAYS TWO THROUGH SEVEN...Friday through Thursday Small chances for thunderstorms may linger into Friday morning. More chances for thunderstorms returns Sunday afternoon and night. LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868- 870-872-874-876-878-182000- 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- 250 PM CDT Thu Jun 17 2021 This Hazardous Weather Outlook is for the open waters of Lake Michigan. .DAY ONE...Tonight Gusty south winds to 30 knots are expected over northern portions of the lake into this evening. A complex of thunderstorms is expected to develop and move southeastward through the central and southern portions of Lake Michigan later this evening and into the overnight hours. A few storms may become severe, with damaging winds the main hazard. Large hail is also possible. Keep up with the forecast for this period. .DAYS TWO THROUGH SEVEN...Friday through Thursday Small chances for thunderstorms may linger into Friday. More chances for thunderstorms returns Sunday afternoon and night. www.weather.gov/mkx
The La Crosse radar (KARX), 99 km away, was scanning. The volume nearest the first event began at 05:29 UTC.
2 thunderstorm wind. Local standard time, as filed.
An estimated wind gust of 60 mph at a resort in Lake Delton. Some trees or tree limbs were blown down in the northern portion of the county.
An old pole barn collapsed onto approximately 100 cows. One cow was reported dead.
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, June 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: 959196, 959193.