Alert archive / Wisconsin / Mesoscale Discussions in 2011

Mesoscale Discussion 733

May 11, 201113 counties in Illinois; 18 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at May 11, 2011, 12:55 PM CDT for 13 counties in Illinois; 18 counties in Wisconsin. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued: May 11, 2011, 12:55 PM CDT (17:55 UTC)
Expired: May 11, 2011, 2:00 PM CDT
In force: 65 min
Issued by: the Storm Prediction Center

All 31 counties

Boone County, IL, Carroll County, IL, DeKalb County, IL, DuPage County, IL, Jo Daviess County, IL, Kane County, IL, Kendall County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Stephenson County, IL, Will County, IL, Winnebago County, IL, Adams County, WI, Columbia County, WI, Dane County, WI, Dodge County, WI, Green County, WI, Green Lake County, WI, Iowa County, WI, Jefferson County, WI, Juneau County, WI, Lafayette County, WI, Marquette County, WI, Monroe County, WI, Richland County, WI, Rock County, WI, Sauk County, WI, Vernon County, WI, Walworth County, WI, Waukesha County, WI

The radar

The Milwaukee radar (KMKX), 61 km from the middle of the area, began a volume at 17:56 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 281May 11, 1:25 PM CDT

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 5.9 hours before the alert went out and 159 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: 2842 J/kg
Mixed-layer CIN: -105 J/kg
Mixed-layer LCL: 931 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: -17 m²/s²
0-3 km storm-relative helicity: 93 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.6

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 11, 1:23 PM CDT	Severe Thunderstorm Watch	SPC	Boone, Bureau, Carroll, Cass, DeKalb, DeWitt and 33 more	6 hr
May 11, 2:18 PM CDT	Mesoscale Discussion	SPC	Adams, Bond, Brown, Calhoun, Cass, Champaign and 30 more	57 min
May 11, 3:38 PM CDT	Mesoscale Discussion	SPC	Boone, Brown, Bureau, Carroll, Cass, Christian and 40 more	2 hr
May 11, 5:56 PM CDT	Severe Thunderstorm Watch	SPC	Boone, Cook, DeKalb, DuPage, Ford, Grundy and 12 more	5 hr
May 10, 8:45 PM CDT	Mesoscale Discussion	SPC	Buffalo, Crawford, Dunn, Eau Claire, Iowa, Jackson and 10 more	90 min
May 11, 3:19 AM CDT	Mesoscale Discussion	SPC	Door, Florence, Forest, Kewaunee, Langlade, Marinette and 2 more	56 min
May 11, 1:16 PM CDT	Mesoscale Discussion	SPC	Brown, Door, Forest, Kewaunee, Langlade, Lincoln and 10 more	119 min

Nearby

Mesoscale Discussions in Wisconsin, 2011 Mesoscale Discussions in Illinois, 2011 Every mesoscale discussion in 2011

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.