Alert archive / Wisconsin / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 567
The Storm Prediction Center issued this severe thunderstorm watch at Dec 15, 2021, 9:44 PM CST for 4 counties in Illinois; Delta County, Menominee County, Michigan; 28 counties in Wisconsin. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 15, 2021, 9:44 PM CST (03:44 UTC)
- Expired
- Dec 16, 2021, 1:00 AM CST
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 70 kt
All 34 counties
Boone County, IL, Lee County, IL, Ogle County, IL, Winnebago County, IL, Delta County, MI, Menominee County, MI, Brown County, WI, Calumet County, WI, Columbia County, WI, Dane County, WI, Dodge County, WI, Door County, WI, Fond du Lac County, WI, Forest County, WI, Green County, WI, Green Lake County, WI, Jefferson County, WI, Kewaunee County, WI, Langlade County, WI, Lincoln County, WI, Manitowoc County, WI, Marinette County, WI, Menominee County, WI, Oconto County, WI, Oneida County, WI, Outagamie County, WI, Rock County, WI, Shawano County, WI, Sheboygan County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI, Waupaca County, WI, Winnebago County, WI
The radar
The Green Bay radar (KGRB), 26 km from the middle of the area, began a volume at 03:43 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
- 70%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 5%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
2 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 15, 9:55 PM CST | Severe Thunderstorm Warning | GRB | Langlade, Lincoln, Marathon, Portage, Waushara, Wood | 65 min |
| Dec 15, 10:45 PM CST | Severe Thunderstorm Warning | GRB | Forest, Langlade, Menominee, Oconto, Oneida, Shawano and 1 more | 45 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 00:00Z, 3.7 hours before the alert went out and 24 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
- 29 J/kg
- Mixed-layer CIN
- -469 J/kg
- Mixed-layer LCL
- 505 m above ground
- 0-6 km bulk shear
- 60 kt
- 0-1 km storm-relative helicity
- 689 m²/s²
- 0-3 km storm-relative helicity
- 687 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
691
WWUS20 KWNS 160342
SEL7
SPC WW 160342
ILZ000-MIZ000-WIZ000-LMZ000-160700-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 567
NWS Storm Prediction Center Norman OK
945 PM CST Wed Dec 15 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Northern Illinois
Southern Upper Michigan
Eastern Wisconsin
Lake Michigan
* Effective this Wednesday night and Thursday morning from 945 PM
until 100 AM CST.
* Primary threats include...
Scattered damaging winds likely with isolated significant gusts
to 80 mph possible
A tornado or two possible
SUMMARY...A fast-moving line of thunderstorms will spread across the
watch area during the next few hours. This line has resulted in
numerous reports of wind damage during the past few hours, and will
likely remain capable of at least occasional severe wind gusts until
after midnight.
The severe thunderstorm watch area is approximately along and 50
statute miles east and west of a line from 30 miles northwest of
Escanaba MI to 50 miles southwest of Rockford IL. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU7).
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 565...WW 566...
AVIATION...A few severe thunderstorms with hail surface and aloft to
0.5 inches. Extreme turbulence and surface wind gusts to 70 knots. A
few cumulonimbi with maximum tops to 450. Mean storm motion vector
24055.
...HartSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 15, 6:00 PM CST | Severe Thunderstorm Watch | SPC | Adams, Brown, Calhoun, Cass, Fulton, Greene and 6 more | 6 hr |
| Dec 15, 9:48 PM CST | Mesoscale Discussion | SPC | Adams, Brown, Calhoun, Cass, Fulton, Greene and 16 more | 87 min |
| Dec 15, 7:11 PM CST | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Bremer, Buchanan, Chickasaw and 13 more | 2 hr |
| Dec 15, 9:03 PM CST | Mesoscale Discussion | SPC | Barron, Chippewa, Clark, Eau Claire, Forest, Langlade and 14 more | 117 min |
Nearby
Severe Thunderstorm Watches in Wisconsin, 2021Severe Thunderstorm Watches in Illinois, 2021Severe Thunderstorm Watches in Michigan, 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.