Widely scattered thunderstorms moved across portions of southeast Minnesota during the late afternoon of July 21st. Just west of Brownsville (Houston County) winds from the storms blew the roof off a barn and a funnel cloud was seen.
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.
Widely scattered thunderstorms moved across portions of southeast Minnesota during the late afternoon of July 21st. Just west of Brownsville (Houston County) winds from the storms blew the roof off a barn and a funnel cloud was seen.
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 Jul 21, 2:00 PM CST, 2 hours 49 minutes earlier.
Area Forecast Discussion National Weather Service La Crosse WI 300 PM CDT Tue Jul 21 2020 .SHORT TERM...(This evening through Wednesday) Issued at 300 PM CDT Tue Jul 21 2020 Mid level trough passing through region has several disturbances and this will drive the forecast focus at least into the evening hours. Resolving expected scale and intensity of convection is tricky. Main short wave trough is near international border in far northern Minnesota with associated cold front extending south. This feature is actually lifting northeast, while a psuedo warm front sits across parts of southeast Minnesota and northeast Iowa marking better low level moisture field to the south. While there is another short wave trough approaching from the northwest, discontinuity between shear and instability fields certainly points to limiting severe weather threat. Better shear fields exist between DLH and EAU in northwest Wisconsin, closer to northern wave. But extensive cloud field and ongoing convection from this morning is somewhat limiting CAPE in that area. Meanwhile shear remains weaker to the south where mixed layer CAPE fields are approaching a modest 1000 J/kg. Earlier Day 1 SPC outlook had increased and expanded risk area, including 5% tornado risk in northern half of area. Since then trends continue to show potential limited to northwest Wisconsin, with marginal risk elsewhere. Again, lots of limiting factors that could squelch intensity and scope of possible severe thunderstorms heading into the evening. As front moves through area later this evening, rain threat should end from west to east as well. Had thought about some valley fog in favored areas but clouds may linger through parts of the night making this scenario less likely as well. .LONG TERM...(Wednesday night through Tuesday) Issued at 300 PM CDT Tue Jul 21 2020 Northwest flow aloft will take hold for Wednesday, keeping cool air in place over the area. Some question as to when morning cloud cover breaks up, as residual low-level moisture lingers for much of the day in some models, especially over north-central Wisconsin. Lapse rates try to steepen diurnally and couldn't totally rule out a stray shower or two, especially over north-central Wisconsin where low clouds may persist longest, but there's not much upper level forcing in the guidance to support widespread shower activity. If sunshine does make an appearance, there could also be some diurnal cumulus that develops in northerly surface flow. All in all, it's looking like a cooler, less Summer-y day, with highs generally remaining in the 70s. If clouds clear out for the overnight, high pressure in the vicinity and light winds could make for a cool night as well, with lows in the 50s and even a few 40s possible in the favored cooler locations of central Wisconsin. Mid level ridging noses into the area for Thursday into Saturday, with warmer air filtering back in as well. Might have to watch out for heat issues by the weekend, as 925 mb temperatures rise from +15C Wed. to +25 to +27C by the weekend, translating to highs rising back into the upper 80s and lower 90s. Southerly flow at the surface will also bring back some moisture/humid conditions, supporting occasional small shower/storm chances Friday into the weekend depending on whether any bits of shortwave energy can top the ridge. Guidance suggests the ridge flattens early next week, portending a return to higher chances for showers/storms. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1235 PM CDT Tue Jul 21 2020 Generally VFR conditions prevail as short wave trough migrates through area to the north. Scattered convection is also complicating matters with pockets of MVFR ceilings. Looking for more convection to pass through area well into the evening so that will have some impacts. A bit tricky what happens with ceilings once short wave / rain threat exits given cooler air aloft and stratus field back to the northwest. Suspect there will be some clearing at times tonight but clouds upstream and possibility of diurnal clouds again tomorrow on backside of wave leads me to think MVFR ceilings will be around at times. Confidence in how these ceilings play out is on lower side. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && SHORT TERM...TJS LONG TERM...Lee AVIATION...Shea
Hazardous Weather Outlook National Weather Service La Crosse WI 942 AM CDT Tue Jul 21 2020 MNZ079-WIZ017-029-032>034-221200- Wabasha-Taylor-Clark-Buffalo-Trempealeau-Jackson- 942 AM CDT Tue Jul 21 2020 This Hazardous Weather Outlook is for parts of southeast Minnesota...western and north central Wisconsin. .DAY ONE...This Afternoon and Tonight Scattered showers and storms are expected today into this evening. An isolated severe storm is possible that could produce damaging wind, hail, and lightning. If a storm would become strong enough, an isolated tornado is not out of the question either, with the main risk along and north of Interstate 94. .DAYS TWO THROUGH SEVEN...Wednesday through Monday There are periodic chances for thunderstorms mainly Friday through the weekend. At this time the risk for severe weather appears low. Later updates will be able to make a determination if severe weather is possible. .SPOTTER INFORMATION STATEMENT... While widespread activation is not anticpated, a few spotter groups may be needed if stronger storms develop later today. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. IAZ008>011-018-019-029-030-MNZ086>088-094>096-WIZ041>044-053>055- 061-221200- Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette- Clayton-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-La Crosse- Monroe-Juneau-Adams-Vernon-Crawford-Richland-Grant- 942 AM CDT Tue Jul 21 2020 This Hazardous Weather Outlook is for portions of north central Iowa...northeast Iowa...southeast Minnesota...central Wisconsin... southwest Wisconsin and west central Wisconsin. .DAY ONE...This Afternoon and Tonight Scattered showers and storms are expected today into this evening. An isolated severe storm is possible that could produce damaging wind, hail, and lightning. .DAYS TWO THROUGH SEVEN...Wednesday through Monday There are periodic chances for thunderstorms mainly Friday through the weekend. At this time the risk for severe weather appears low. Later updates will be able to make a determination if severe weather is possible. .SPOTTER INFORMATION STATEMENT... Due to the conditional storm threat and isolated coverage, storm spotter activation may not be needed today. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. Shea
The La Crosse radar (KARX), 17 km away, was scanning. The volume nearest the first event began at 22:51 UTC.
1 thunderstorm wind, 1 funnel cloud. Local standard time, as filed.
The tin roof of a barn was blown off.
A funnel cloud was sighted just west of Brownsville.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2020Every state in 2020This day in weather historyWarnings in Minnesota, July 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: 909101, 909100.