Alert archive / Illinois / Mesoscale Discussions in 2014

Mesoscale Discussion 579

May 12, 201419 counties in Illinois; 18 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at May 12, 2014, 9:51 AM CDT for 19 counties in Illinois; 18 counties in Wisconsin. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: May 12, 2014, 9:51 AM CDT (14:51 UTC)
Expired: May 12, 2014, 11:15 AM CDT
In force: 84 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 37 counties

Boone County, IL, Bureau County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Grundy County, IL, Kane County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Putnam County, IL, Stephenson County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Columbia County, WI, Dane County, WI, Dodge County, WI, Fond du Lac County, WI, Green County, WI, Green Lake County, WI, Jefferson County, WI, Kenosha County, WI, Marquette County, WI, Milwaukee County, WI, Ozaukee County, WI, Racine County, WI, Rock County, WI, Sauk County, WI, Sheboygan County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI

The radar

The Milwaukee radar (KMKX), 60 km from the middle of the area, began a volume at 14:54 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 149May 12, 10:05 AM CDT

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 2.9 hours before the alert went out and 171 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: 850 J/kg
Mixed-layer CIN: -21 J/kg
Mixed-layer LCL: 666 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 223 m²/s²
0-3 km storm-relative helicity: 216 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 5.6

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, 8:32 PM CDT	Mesoscale Discussion	SPC	DeWitt, Ford, Iroquois, Livingston, McLean	58 min
May 12, 10:02 AM CDT	Severe Thunderstorm Watch	SPC	Boone, Cook, DeKalb, DuPage, Kane, Lake and 4 more	6 hr
May 12, 11:54 AM CDT	Mesoscale Discussion	SPC	Adams, Brown, Bureau, Carroll, Fulton, Hancock and 16 more	2 hr
May 12, 1:00 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Bureau, Carroll, Hancock, Henderson, Henry and 8 more	7 hr
May 12, 1:06 PM CDT	Mesoscale Discussion	SPC	Boone, Cook, DeKalb, DuPage, Kane, Lake and 6 more	54 min
May 12, 3:21 PM CDT	Mesoscale Discussion	SPC	Adams, Hancock, Henderson, Jo Daviess, McDonough, Mercer and 2 more	54 min
May 12, 3:49 PM CDT	Severe Thunderstorm Watch	SPC	Boone, Cook, DeKalb, DuPage, Kane, Kendall and 6 more	7 hr
May 12, 6:56 PM CDT	Mesoscale Discussion	SPC	Boone, Jo Daviess, Lake, McHenry, Stephenson, Winnebago	64 min

Nearby

Mesoscale Discussions in Illinois, 2014 Mesoscale Discussions in Wisconsin, 2014 Every mesoscale discussion in 2014

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.