Alert archive / Wisconsin / Mesoscale Discussions in 2024

Mesoscale Discussion 883

May 21, 20244 counties in Illinois; 27 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at May 21, 2024, 7:56 PM CDT for 4 counties in Illinois; 27 counties in Wisconsin. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued: May 21, 2024, 7:56 PM CDT (00:56 UTC)
Expired: May 21, 2024, 9:00 PM CDT
In force: 64 min
Issued by: the Storm Prediction Center
Concerning: Tornado watch 281...282

All 31 counties

Boone County, IL, McHenry County, IL, Stephenson County, IL, Winnebago County, IL, Adams County, WI, Brown County, WI, Calumet County, WI, Columbia County, WI, Dane County, WI, Dodge County, WI, Fond du Lac County, WI, Green County, WI, Green Lake County, WI, Jefferson County, WI, Langlade County, WI, Marathon County, WI, Marquette County, WI, Menominee County, WI, Oconto County, WI, Outagamie County, WI, Ozaukee County, WI, Portage County, WI, Rock County, WI, Shawano 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 Milwaukee radar (KMKX), 101 km from the middle of the area, began a volume at 00:59 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.

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 00:00Z, 0.9 hours before the alert went out and 120 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 442 J/kg
Mixed-layer CIN: -98 J/kg
Mixed-layer LCL: 1016 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 49 m²/s²
0-3 km storm-relative helicity: 149 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 21, 7:13 PM CDT	Tornado Watch	SPC	Boone, Bureau, DeKalb, Kane, Kendall, LaSalle and 6 more	5 hr
May 21, 7:55 PM CDT	Mesoscale Discussion	SPC	Adams	2 hr
May 21, 11:45 PM CDT	Mesoscale Discussion	SPC	Brown, Door, Kewaunee, Manitowoc, Ozaukee, Sheboygan and 1 more	2 hr

Nearby

Mesoscale Discussions in Wisconsin, 2024 Mesoscale Discussions in Illinois, 2024 Every mesoscale discussion in 2024

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.