Alert archive / Illinois / Mesoscale Discussions in 2012

Mesoscale Discussion 687

May 3, 201213 counties in Illinois; 5 counties in Indiana

The Storm Prediction Center issued this mesoscale discussion at May 3, 2012, 10:29 PM CDT for 13 counties in Illinois; 5 counties in Indiana. It was in force for 61 min.

The area

The outline as issued.

The facts

Issued: May 3, 2012, 10:29 PM CDT (03:29 UTC)
Expired: May 3, 2012, 11:30 PM CDT
In force: 61 min
Issued by: the Storm Prediction Center

Counties Cook County, IL, DeKalb County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Will County, IL, Benton County, IN, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN

The radar

The Chicago radar (KLOT), 43 km from the middle of the area, began a volume at 03:28 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 235May 3, 11:35 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 3.5 hours before the alert went out and 138 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: 1905 J/kg
Mixed-layer CIN: -30 J/kg
Mixed-layer LCL: 1071 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 12 m²/s²
0-3 km storm-relative helicity: 96 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

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 3, 7:09 PM CDT	Tornado Watch	SPC	Adams, Brown, Pike, Rock Island	6 hr
May 3, 11:18 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Bureau, Cass, DeWitt, Fulton and 22 more	27 min
May 3, 11:34 PM CDT	Severe Thunderstorm Watch	SPC	Bureau, Cass, Champaign, DeWitt, Ford, Fulton and 25 more	5 hr
May 4, 12:53 AM CDT	Severe Thunderstorm Watch	SPC	Adams, Brown	4 hr
May 4, 2:16 AM CDT	Mesoscale Discussion	SPC	Adams, Brown, Bureau, Cass, DeWitt, Ford and 25 more	119 min
May 4, 11:36 AM CDT	Mesoscale Discussion	SPC	Clay, Clinton, Edwards, Franklin, Gallatin, Hamilton and 17 more	84 min
May 4, 1:29 PM CDT	Severe Thunderstorm Watch	SPC	Edwards, Wabash, White	5 hr
May 4, 3:16 PM CDT	Mesoscale Discussion	SPC	Clark, Crawford, Daviess, Dubois, Floyd, Gibson and 19 more	59 min
May 4, 6:52 PM CDT	Mesoscale Discussion	SPC	Boone, Delaware, Fayette, Franklin, Hamilton, Hancock and 12 more	53 min

Nearby

Mesoscale Discussions in Illinois, 2012 Mesoscale Discussions in Indiana, 2012 Every mesoscale discussion in 2012

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.