Alert archive / Wisconsin / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 278
The Storm Prediction Center issued this severe thunderstorm watch at Jun 17, 2021, 10:01 PM CDT for 16 counties in Iowa; 7 counties in Minnesota; 39 counties in Wisconsin. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 17, 2021, 10:01 PM CDT (03:01 UTC)
- Expired
- Jun 18, 2021, 4:00 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 62 counties
Allamakee County, IA, Bremer County, IA, Butler County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clayton County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Hancock County, IA, Howard County, IA, Humboldt County, IA, Mitchell County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Dodge County, MN, Fillmore County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Wabasha County, MN, Winona County, MN, Adams County, WI, Buffalo County, WI, Calumet County, WI, Clark County, WI, Columbia County, WI, Crawford County, WI, Dane County, WI, Dodge County, WI, Fond du Lac County, WI, Grant County, WI, Green County, WI, Green Lake County, WI, Iowa County, WI, Jackson County, WI, Jefferson County, WI, Juneau County, WI, Kenosha County, WI, La Crosse County, WI, Lafayette County, WI, Marquette County, WI, Milwaukee County, WI, Monroe County, WI, Outagamie County, WI, Ozaukee County, WI, Portage County, WI, Racine County, WI, Richland County, WI, Rock County, WI, Sauk County, WI, Sheboygan County, WI, Trempealeau County, WI, Vernon County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI, Waupaca County, WI, Waushara County, WI, Winnebago County, WI, Wood County, WI
The radar
The La Crosse radar (KARX), 13 km from the middle of the area, began a volume at 03:02 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 60%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 17, 10:22 PM CDT | Severe Thunderstorm Warning | ARX | Wabasha, Winona | 53 min |
| Jun 17, 10:46 PM CDT | Severe Thunderstorm Warning | ARX | Houston, Winona | 44 min |
| Jun 17, 11:14 PM CDT | Severe Thunderstorm Warning | ARX | Houston | 25 min |
| Jun 17, 11:56 PM CDT | Severe Thunderstorm Warning | ARX | Adams, Juneau | 34 min |
| Jun 18, 12:14 AM CDT | Severe Thunderstorm Warning | MKX | Columbia, Marquette, Sauk | 37 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Minneapolis, MN (KMPX), launched 00:00Z, 3.0 hours before the alert went out and 219 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 61 J/kg
- Mixed-layer CIN
- -387 J/kg
- Mixed-layer LCL
- 1555 m above ground
- 0-6 km bulk shear
- 55 kt
- 0-1 km storm-relative helicity
- -13 m²/s²
- 0-3 km storm-relative helicity
- 56 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
533
WWUS20 KWNS 180259
SEL8
SPC WW 180259
IAZ000-MNZ000-WIZ000-180900-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 278
NWS Storm Prediction Center Norman OK
1000 PM CDT Thu Jun 17 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
North-central/Northeast Iowa
Southeast Minnesota
Central/Southern Wisconsin
* Effective this Thursday night and Friday morning from 1000 PM
until 400 AM CDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph likely
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
A tornado or two possible
SUMMARY...Organized clusters of storms are expected to accelerate
east-southeastward across central/southern Wisconsin, while
additional storms develop across southeast Minnesota and northern
Iowa late this evening into the overnight. Damaging winds and severe
hail can be expected through at least the early/middle part of the
overnight.
The severe thunderstorm watch area is approximately along and 70
statute miles north and south of a line from 35 miles north
northwest of Mason City IA to 35 miles north of Milwaukee WI. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU8).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 276...WW 277...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
29040.
...GuyerSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 17, 7:02 PM CDT | Mesoscale Discussion | SPC | Allamakee, Howard, Mitchell, Winnebago, Winneshiek, Worth | 88 min |
| Jun 17, 9:01 PM CDT | Mesoscale Discussion | SPC | Allamakee, Howard, Mitchell, Winneshiek | 89 min |
| Jun 17, 10:52 PM CDT | Mesoscale Discussion | SPC | Allamakee, Howard, Winneshiek | 83 min |
| Jun 18, 1:34 AM CDT | Mesoscale Discussion | SPC | Allamakee | 116 min |
| Jun 17, 7:22 PM CDT | Severe Thunderstorm Watch | SPC | Blue Earth, Brown, Dakota, Faribault, Freeborn, Goodhue and 9 more | 4 hr |
| Jun 18, 5:03 PM CDT | Mesoscale Discussion | SPC | Becker, Beltrami, Cass, Clay, Clearwater, Crow Wing and 9 more | 87 min |
Nearby
Severe Thunderstorm Watches in Wisconsin, 2021Severe Thunderstorm Watches in Iowa, 2021Severe Thunderstorm Watches in Minnesota, 2021Every severe thunderstorm watch in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.