Alert archive / Wisconsin / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 416
The Storm Prediction Center issued this severe thunderstorm watch at Aug 8, 2021, 1:59 PM CDT for 26 counties in Wisconsin. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 8, 2021, 1:59 PM CDT (18:59 UTC)
- Expired
- Aug 8, 2021, 8:00 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 26 counties
Adams County, WI, Brown County, WI, Calumet County, WI, Clark County, WI, Columbia County, WI, Dodge County, WI, Fond du Lac County, WI, Green Lake County, WI, Jackson County, WI, Juneau County, WI, Kewaunee County, WI, Manitowoc County, WI, Marathon County, WI, Marquette County, WI, Monroe County, WI, Outagamie County, WI, Portage County, WI, Richland County, WI, Sauk County, WI, Shawano County, WI, Sheboygan County, WI, Vernon County, WI, Waupaca County, WI, Waushara County, WI, Winnebago County, WI, Wood County, WI
The radar
The Green Bay radar (KGRB), 76 km from the middle of the area, began a volume at 19:02 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
- 2%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
8 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 8, 3:32 PM CDT | Severe Thunderstorm Warning | ARX | Adams | 31 min |
| Aug 8, 3:54 PM CDT | Severe Thunderstorm Warning | GRB | Waushara | 51 min |
| Aug 8, 4:16 PM CDT | Severe Thunderstorm Warning | GRB | Waushara, Winnebago | 29 min |
| Aug 8, 4:24 PM CDT | Severe Thunderstorm Warning | MKX | Green Lake, Marquette | 36 min |
| Aug 8, 4:30 PM CDT | Severe Thunderstorm Warning | GRB | Outagamie, Portage, Shawano, Waupaca, Waushara, Winnebago | 60 min |
| Aug 8, 4:46 PM CDT | Severe Thunderstorm Warning | GRB | Waushara, Winnebago | 29 min |
| Aug 8, 5:45 PM CDT | Severe Thunderstorm Warning | MKX | Sheboygan | 30 min |
| Aug 8, 6:46 PM CDT | Severe Thunderstorm Warning | GRB | Brown, Door, Kewaunee | 29 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
Green Bay/Straub, WI (KGRB), launched 12:00Z, 7.0 hours before the alert went out and 75 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
- 445 J/kg
- Mixed-layer CIN
- -23 J/kg
- Mixed-layer LCL
- 568 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- 108 m²/s²
- 0-3 km storm-relative helicity
- 44 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
490 WWUS20 KWNS 081857 SEL6 SPC WW 081857 WIZ000-LMZ000-090100- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 416 NWS Storm Prediction Center Norman OK 200 PM CDT Sun Aug 8 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central Wisconsin Lake Michigan * Effective this Sunday afternoon and evening from 200 PM until 800 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1 inch in diameter possible A tornado or two possible SUMMARY...Clusters of thunderstorms are expected to develop and spread northeastward across central Wisconsin through the afternoon. The storm environment favors a mix of multicell clusters with damaging winds of 60-70 mph and isolated large hail around 1 inch diameter. A few supercells will also be possible, with the attendant threat for a brief tornado or two. The severe thunderstorm watch area is approximately along and 45 statute miles north and south of a line from 10 miles north northeast of Manitowoc WI to 20 miles west northwest of Camp Douglas WI. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU6). 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 415... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 21020. ...Thompson
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 8, 12:57 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Calumet, Columbia, Crawford, Dodge and 22 more | 93 min |
| Aug 8, 3:53 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Calumet, Clark, Columbia, Dodge and 22 more | 97 min |
Nearby
Severe Thunderstorm Watches in Wisconsin, 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.