Thunderstorms developed along a warm front over southwest Wisconsin during the early evening of March 28th. These storms spawned a tornado near Potosi (Grant County) that was on the ground for just over 6 miles before dissipating west of Ellenboro (Grant County).
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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 ARX wrote it up.
Thunderstorms developed along a warm front over southwest Wisconsin during the early evening of March 28th. These storms spawned a tornado near Potosi (Grant County) that was on the ground for just over 6 miles before dissipating west of Ellenboro (Grant County). One house and numerous farm buildings were damaged along with trees and power lines along the path of the tornado.
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 Mar 28, 6:02 PM CST, 1 hour 33 minutes earlier.
Area Forecast Discussion National Weather Service La Crosse WI 702 PM CDT Sat Mar 28 2020 .SHORT TERM...(This evening through Sunday) Issued at 215 PM CDT Sat Mar 28 2020 At 2 PM, a rapidly strengthening surface low was just moving into southwest Iowa. The warm front was located over southern Iowa. Temperatures were in the 40s north of this front and in the 60s and 70s south of this front. The models continue to show that this low will move northeast this afternoon and tonight. It continues to look like there will be a potential in the HRRR and RAP that the warm sector could get into the southern portions of Fayette and Clayton counties in northeast Iowa and Grant County in southwest Wisconsin. Surface based CAPES may climb up to 750 J/kg. Helicity is up to 250 and the 0-1 km shear is 40 knots. Due to this, there is still a potential of isolated tornadoes and damaging winds. These storms will move at 50 to 60 mph. Further to the north, the elevated CAPES will climb up to 1000 J/kg up to Interstate 90. With the shear over 40 knots, some of the storms could become supercells. With a straight-line hodograph, there could be right and left supercells. The main threat will be hail. The largest hail will likely range from 1 to 1.5 inches. From tonight into Sunday, a deformation band of rain will move east across the area. Additional rain will range from 0.25 to 0.75 inches. Northwest winds will gust into the 30 to 40 mph from late Sunday morning into the afternoon. .LONG TERM...(Sunday night through Saturday) Issued at 215 PM CDT Sat Mar 28 2020 On Sunday evening, the deformation band of precipitation will move quickly east out of the area. Before it exits the area, the rain may mix with some light snow north of Interstate 94. As the pressure gradient relaxes during the late evening and overnight, the sustained wind and wind gusts will gradually diminish. As we head into the April, a shortwave trough and cold front will move out of the Northern Plains and through the Upper Mississippi River Valley. The models continue to struggle on the timing of when this colder air will move into the region. As a result, just stayed with the NBM. In the wake of this front, high temperatures will range from the mid- 30s to mid-40s, and low temperatures will be mainly in the 20s. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 702 PM CDT Sat Mar 28 2020 LIFR conditions are expected tonight into tomorrow morning at KRST, with MVFR to IFR conditions at KLSE. A narrow line of showers with occasional thunder are moving through KRST this evening. These should continue to move northeast over the next 1-2 hours, reaching KLSE by around 01Z to 02Z. The line is expected to quickly move northeast, exiting both TAF sites by 03Z. Some small hail may be possible in stronger storms within this line. Scattered to isolated showers will be found following this line as the dry slot of approaching low pressure wraps into the area, but low ceilings are expected to continue at KRST and KLSE. Will have to watch for patchy fog development as well overnight, but confidence is lower in this occurring. There will be a small window of a few hours later tonight that KLSE might be able to break out of the lower IFR/MVFR ceilings, but several models keep this to the southeast of KLSE and will opt to keep low clouds in the TAF for now. Shower activity will pick up again late tonight into Sunday morning as rain wraps around the back side of low pressure moving east across the area. Gusty east winds this evening will decrease tonight, then turn around to the northwest and increase again Sunday morning on the back side of the low pressure system. Gusts of 30 to 35 knots are possible tomorrow, especially at KRST. && .HYDROLOGY... Issued at 215 PM CDT Sat Mar 28 2020 Rainfall totals will range from 0.25 to 0.75 inch across the area through tonight. This is about a quarter inch than the previous forecast. This was done due to the speed of the showers and storms late this afternoon and evening and the dry slot which will be moving into the area tonight. This rain will result in rises on area rivers. Those on the Black and Kickapoo rivers may approach minor flood stage early next week. Meanwhile, those along the Mississippi River may see minor flooding during the latter half of next week. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && SHORT TERM...Boyne LONG TERM...Boyne AVIATION...Lee HYDROLOGY...Boyne
Hazardous Weather Outlook National Weather Service La Crosse WI 547 AM CDT Sat Mar 28 2020 IAZ008>011-018-019-MNZ079-086>088-094>096-WIZ017-029-032>034- 041>044-053>055-291100- Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Wabasha- Dodge-Olmsted-Winona-Mower-Fillmore-Houston-Taylor-Clark-Buffalo- Trempealeau-Jackson-La Crosse-Monroe-Juneau-Adams-Vernon-Crawford- Richland- 547 AM CDT Sat Mar 28 2020 This Hazardous Weather Outlook is for portions of southeast Minnesota...northeast Iowa and southwest into central Wisconsin. .DAY ONE...Today and Tonight Thunderstorms are expected today with the possibility for strong to isolated severe storms early this afternoon into this evening. The main threat will be hail. 25 to 35 mph wind gusts out of the east are expected this afternoon. .DAYS TWO THROUGH SEVEN...Sunday through Friday 30 to 40 mph wind gusts out of the northwest are expected on Sunday. Widespread rainfall near 1 inch is expected through Sunday. This will lead to river rises into the upcoming week, with flooding possible in some areas. .SPOTTER INFORMATION STATEMENT... Spotter reports could be needed this afternoon. Please relay any reports to the National Weather Service. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. IAZ029-030-WIZ061-291100- Fayette-Clayton-Grant- 547 AM CDT Sat Mar 28 2020 This Hazardous Weather Outlook is for portions of northeast Iowa and far southwest Wisconsin. .DAY ONE...Today and Tonight Thunderstorms are expected today with the possibility for strong to severe storms early this afternoon into this evening. The main threat will be hail, but damaging winds and isolated tornadoes cannot be ruled out. The tornado and damaging wind threat will be from around 5 PM to 9 PM. .DAYS TWO THROUGH SEVEN...Sunday through Friday 30 to 40 mph wind gusts out of the northwest are expected on Sunday. Widespread rainfall near 1 inch is expected through Sunday. This will lead to river rises into the upcoming week, with flooding possible in some areas. .SPOTTER INFORMATION STATEMENT... Spotter reports could be needed this afternoon. Please relay any reports to the National Weather Service. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. CA
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
724 PM CDT SAT MAR 28 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0721 PM HAIL MONONA 43.05N 91.39W
03/28/2020 U0.75 INCH CLAYTON IA PUBLIC
REPORT FROM MPING: DIME (0.75 IN.).
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
733 PM CDT SAT MAR 28 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0715 PM HAIL ELKADER 42.86N 91.40W
03/28/2020 E1.00 INCH CLAYTON IA LAW ENFORCEMENT
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
734 PM CDT SAT MAR 28 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0715 PM FUNNEL CLOUD SAINT OLAF 42.93N 91.39W
03/28/2020 CLAYTON IA TRAINED SPOTTER
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
750 PM CDT SAT MAR 28 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0745 PM HAIL HARPERS FERRY 43.20N 91.15W
03/28/2020 E0.25 INCH ALLAMAKEE IA BROADCAST MEDIA
REPORTED BY WXOW. STRONG WINDS ALSO
REPORTED.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
804 PM CDT SAT MAR 28 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0756 PM HAIL PATCH GROVE 42.94N 90.97W
03/28/2020 E0.50 INCH GRANT WI PUBLIC
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
829 PM CDT SAT MAR 28 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0828 PM HAIL BOSCOBEL 43.14N 90.71W
03/28/2020 E0.25 INCH GRANT WI PUBLIC
&&The Quad Cities radar (KDVN), 122 km away, was scanning. The volume nearest the first event began at 01:36 UTC.
1 tornado. Local standard time, as filed.
An EF1 tornado touched down north of Potosi and move northeast for 6 miles before dissipating west of Ellenboro. One house, numerous farm buildings, trees and power lines were damaged along the path of the tornado.
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, March 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: 878426.