Alert archive / Illinois / Mesoscale Discussions in 2008

Mesoscale Discussion 775

May 2, 200836 counties in Illinois; Rock County, Wisconsin

The Storm Prediction Center issued this mesoscale discussion at May 2, 2008, 3:05 PM CDT for 36 counties in Illinois; Rock County, Wisconsin. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued: May 2, 2008, 3:05 PM CDT (20:05 UTC)
Expired: May 2, 2008, 5:00 PM CDT
In force: 115 min
Issued by: the Storm Prediction Center

All 37 counties

Boone County, IL, Bureau County, IL, Carroll County, IL, Champaign County, IL, DeKalb County, IL, DeWitt County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Henry County, IL, Iroquois County, IL, Jo Daviess County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Marshall County, IL, McHenry County, IL, McLean County, IL, Ogle County, IL, Peoria County, IL, Piatt County, IL, Putnam County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Vermilion County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Woodford County, IL, Rock County, WI

The radar

The Chicago radar (KLOT), 92 km from the middle of the area, began a volume at 20:08 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.

Tornado Watch 252May 2, 4:30 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 8.1 hours before the alert went out and 119 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: 729 J/kg
Mixed-layer CIN: -85 J/kg
Mixed-layer LCL: 730 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 251 m²/s²
0-3 km storm-relative helicity: 261 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 8.4

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 2, 5:00 AM CDT	Severe Thunderstorm Watch	SPC	Adams, Brown, Calhoun, Greene, Jersey, Pike	5 hr
May 2, 9:48 AM CDT	Mesoscale Discussion	SPC	Champaign, Clark, Clay, Coles, Crawford, Cumberland and 13 more	117 min
May 2, 10:44 AM CDT	Tornado Watch	SPC	Alexander, Edwards, Gallatin, Hamilton, Hardin, Johnson and 7 more	9 hr
May 2, 11:05 AM CDT	Mesoscale Discussion	SPC	Jo Daviess	115 min
May 2, 12:12 PM CDT	Mesoscale Discussion	SPC	Alexander, Gallatin, Hardin, Johnson, Massac, Pope and 2 more	2 hr
May 2, 3:47 PM CDT	Mesoscale Discussion	SPC	Adams, Columbia, Crawford, Dane, Dodge, Fond du Lac and 11 more	118 min
May 2, 4:31 PM CDT	Tornado Watch	SPC	Adams, Columbia, Crawford, Dane, Dodge, Grant and 14 more	3 hr
May 2, 6:47 PM CDT	Mesoscale Discussion	SPC	Columbia, Dodge, Fond du Lac, Green Lake, Jefferson, Marquette and 1 more	88 min

Nearby

Mesoscale Discussions in Illinois, 2008 Mesoscale Discussions in Wisconsin, 2008 Every mesoscale discussion in 2008

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.