Two rounds of storms moved across portions of western Wisconsin on August 10th. The first round occurred in the morning and produced a wind gust of 58 mph at the Black River Falls airport (Jackson County) and blew down some trees near New Miner (Juneau County) and Friendship (Adams 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 ARX wrote it up.
Two rounds of storms moved across portions of western Wisconsin on August 10th. The first round occurred in the morning and produced a wind gust of 58 mph at the Black River Falls airport (Jackson County) and blew down some trees near New Miner (Juneau County) and Friendship (Adams County). The second round of storms occurred in the afternoon and produced a brief EF-0 tornado near Burton (Grant County). There were also several reports of wind gusts of 60 to 65 mph and numerous trees down across other parts of Grant 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 La Crosse, WI wrote its last area forecast discussion before the first event at Aug 10, 5:55 AM CST, 0 minutes earlier.
Area Forecast Discussion National Weather Service La Crosse WI 655 AM CDT Mon Aug 10 2020 .SHORT TERM...(Today and tonight) Issued at 221 AM CDT Mon Aug 10 2020 Early morning radar imagery showed a cluster of severe storms moving through the Twin Cities area, just ahead of a southwest to northeast oriented surface cold front. SPC mesoanalysis suggests 3000+ J/kg of MUCAPE ahead of these storms with effective shear of 35 to 40 kts continuing southeast with them. In addition, low level moisture transport, while not particularly strong, does look to persist through sunrise. Therefore, thinking these storms should continue into the forecast area, with additional development expected as the front continues to advance southeastward. Time of day suggests damaging wind would be tough to come by, but have seen a 50+ kt gust or two at times as additional cores form and combine with ongoing convection. That said, hail should be the main threat as these storms move in this morning. Meanwhile, expect additional storms to form across southern South Dakota and eventually develop into an eastward moving MCS that tracks across Iowa and possibly clips far southwest Wisconsin today. Already seeing some signs of this occurring with light showers forming along what seems to be a weak secondary surface boundary. Eventually, expect this to develop into an eastward moving MCS that moves across Iowa today. It should eventually catch up to the main boundary and bring a strong to severe storm threat to far southern portions of the forecast area. Said threat will really depend on how far southeast the main front makes it, with areas behind said front seeing much less of a threat. Otherwise, could see some lighter showers farther north associated with the aforementioned secondary boundary as it slowly sinks southward this afternoon. Any precip should exit by late afternoon/early evening with high pressure building in behind the front. This should lead to clearing skies tonight, with perhaps some fog forming in the MS River tributaries, though winds just above the surface look like they might be a bit too strong for more widespread development. .LONG TERM...(Tuesday through Sunday) Issued at 221 AM CDT Mon Aug 10 2020 Upper level flow looks to remain zonal through much of the period with surface high pressure building in and leading to quiet weather through Wednesday morning or so. Models are in good agreement then of several shortwave troughs moving through the forecast area and bringing off and on shower and storm chances through the remainder of the period. While quite a bit of model spread remains timing and strength (though nothing looks overly strong), GEFS members seem to be in pretty good agreement of the first chances moving in Wednesday. That said, the 10.00Z GFS/ECMWF/NAM all remain dry, so forecast confidence remains fairly low. Otherwise, expect seasonable temperatures into next weekend, with highs generally in the 80s and lows in the 50s and 60s. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 655 AM CDT Mon Aug 10 2020 Cigs: some potential for a brief period of MVFR cigs post shra/ts and passage of cold front. Not seeing much evidence in obs so will leave VFR for the moment. Skies look to clear this afternoon with VFR expected through Tue. WX/vsby: SHRA/TS look to clear KLSE by 14z with some impacts to vsby and potentially small hail. With clearing skies tonight and recent rains, fog could develop. Low level moisture on the decrease with passage of cold front though, and have opted to not add to forecast for now. Winds: swinging to the north with passage of cold front. Could have higher gusts at KLSE with any storm through 14z. Generally light tonight. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && SHORT TERM...Rieck/CA LONG TERM...CA AVIATION...Rieck
Hazardous Weather Outlook National Weather Service La Crosse WI 308 AM CDT Mon Aug 10 2020 IAZ008>011-018-019-029-030-WIZ054-055-061-110815- Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette- Clayton-Crawford-Richland-Grant- 308 AM CDT Mon Aug 10 2020 This Hazardous Weather Outlook is for portions of northeast Iowa and southwest Wisconsin. .DAY ONE...Today and Tonight Scattered storms today. A few could be strong with hail, gusty winds and locally heavy rain the threats. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday There are mostly small storm chances Wednesday into Sunday. The threat for organized severe weather is low at this time. .SPOTTER INFORMATION STATEMENT... Rainfall reports are appreciated. Spotter activation is not anticipated. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. MNZ079-086>088-094>096-WIZ017-029-032>034-041>044-053-110815- Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-Taylor-Clark- Buffalo-Trempealeau-Jackson-La Crosse-Monroe-Juneau-Adams-Vernon- 308 AM CDT Mon Aug 10 2020 This Hazardous Weather Outlook is for portions of southeast Minnesota...and western into north central Wisconsin. .DAY ONE...Today and Tonight Scattered storms, mainly this morning. A few could be strong to severe early with a hail, damaging wind and heavy rain threat. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday There are mostly small storm chances Wednesday into Sunday. The threat for organized severe weather is low at this time. .SPOTTER INFORMATION STATEMENT... Rainfall reports are appreciated. Timing of early morning storms likely precludes spotter activation. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. Rieck/CA
Special Weather Statement National Weather Service La Crosse WI 358 AM CDT Mon Aug 10 2020 MNZ079-086>088-WIZ032-033-101100- Wabasha-Dodge-Olmsted-Winona-Buffalo-Trempealeau- Including the cities of Wabasha, Dodge Center, Rochester, Winona, Alma, Arcadia, and Whitehall 358 AM CDT Mon Aug 10 2020 ...Line of Strong to Severe Storms to Impact parts of Southeast Minnesota into West-Central Wisconsin This Morning... A line of storms will continue eastward into parts of southeast Minnesota and west-central Wisconsin this morning. These storms have a history of producing large hail, strong to damaging wind gusts, and heavy rainfall. Be sure to have multiple ways to receive warnings and take shelter indoors if storms approach your location. CA
Special Weather Statement National Weather Service La Crosse WI 455 AM CDT Mon Aug 10 2020 MNZ094>096-101200- Mower-Fillmore-Houston- Including the cities of Austin, Preston, and Caledonia 455 AM CDT Mon Aug 10 2020 ...Strong to Severe Storms to Impact parts of Southeast Minnesota This Morning... Strong to severe storms will continue eastward in parts of southeast Minnesota this morning. These storms have a history of producing large hail, strong to damaging wind gusts, and heavy rainfall. Be sure to have multiple ways to receive warnings and take shelter indoors if storms approach your location. CA
Special Weather Statement National Weather Service La Crosse WI 609 AM CDT Mon Aug 10 2020 WIZ033-034-041-042-101315- Trempealeau-Jackson-La Crosse-Monroe- Including the cities of Arcadia, Whitehall, Black River Falls, La Crosse, Sparta, and Tomah 609 AM CDT Mon Aug 10 2020 ...Strong to Severe Thunderstorms Moving through West-Central Wisconsin... Strong to severe storms will continue eastward in parts of west-central Wisconsin this morning. Some storms will be capable of producing large hail, strong to damaging wind gusts, and heavy rainfall. Be sure to have multiple ways to receive warnings and take shelter indoors if storms approach your location. CA
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
626 AM CDT MON AUG 10 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0622 AM HAIL 1 W WILSON 43.95N 91.72W
08/10/2020 E0.75 INCH WINONA MN TRAINED SPOTTER
&&
RIECKPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
640 AM CDT MON AUG 10 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0633 AM TSTM WND GST ETTRICK 44.17N 91.27W
08/10/2020 E45 MPH TREMPEALEAU WI TRAINED SPOTTER
TRAINED SPOTTER REPORTED 45 MPH WIND GUST
AND PEA SIZE HAIL.
&&The La Crosse radar (KARX), 55 km away, was scanning. The volume nearest the first event began at 11:57 UTC.
13 thunderstorm wind, 1 tornado. Local standard time, as filed.
The automated weather observing equipment at the Black River Falls airport measured a 58 mph wind gust.
Trees were blown down northeast of New Miner.
Trees were blown down north of Friendship.
Trees were snapped off near Glen Haven.
A 63 mph wind gust occurred in Patch Grove.
A brief tornado touched down south of Burton and was on the ground for about a half mile. The tornado damaged two farm outbuildings, hardwood trees and downed power lines.
An estimated 60 mph wind gust occurred in Bloomington.
Trees and power lines were blown down in Potosi.
A pole barn was destroyed south of Lancaster.
An estimated 60 mph wind gust occurred in Lancaster causing power outages.
Trees were blown down east of Potosi.
An estimated 62 mph wind gust occurred north of Platteville causing some tree damage.
Trees were damaged and power outages occurred just west of Platteville.
Trees were blown down in Platteville. One tree fell on a house and four roads were blocked by the downed trees.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2020Every state in 2020This day in weather historyThe tornado archive for Wisconsin, 2020Warnings in Wisconsin, August 2020
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: 914360, 914366, 914367, 918347, 914361, 914389, 914371, 914377, 918352, 914372, 914387, 914374, 914381, 914379.