Alert archive / Illinois / Mesoscale Discussions in 2012

Mesoscale Discussion 691

May 4, 20124 states

The Storm Prediction Center issued this mesoscale discussion at May 4, 2012, 2:16 AM CDT for 4 states. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued: May 4, 2012, 2:16 AM CDT (07:16 UTC)
Expired: May 4, 2012, 4:15 AM CDT
In force: 119 min
Issued by: the Storm Prediction Center

All 78 counties

Appanoose County, IA, Davis County, IA, Decatur County, IA, Des Moines County, IA, Henry County, IA, Jefferson County, IA, Lee County, IA, Louisa County, IA, Monroe County, IA, Page County, IA, Ringgold County, IA, Taylor County, IA, Van Buren County, IA, Wapello County, IA, Wayne County, IA, Adams County, IL, Brown County, IL, Bureau County, IL, Cass County, IL, DeWitt County, IL, Ford County, IL, Fulton County, IL, Grundy County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Iroquois County, IL, Kankakee County, IL, Knox County, IL, LaSalle County, IL, Livingston County, IL, Logan County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McLean County, IL, Menard County, IL, Mercer County, IL, Peoria County, IL, Putnam County, IL, Schuyler County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL, Will County, IL, Woodford County, IL, Benton County, IN, Jasper County, IN, Newton County, IN, Pulaski County, IN, White County, IN, Adair County, MO, Andrew County, MO, Atchison County, MO, Caldwell County, MO, Chariton County, MO, Clark County, MO, Clinton County, MO, Daviess County, MO, DeKalb County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Holt County, MO, Knox County, MO, Lewis County, MO, Linn County, MO, Livingston County, MO, Macon County, MO, Marion County, MO, Mercer County, MO, Nodaway County, MO, Putnam County, MO, Schuyler County, MO, Scotland County, MO, Shelby County, MO, Sullivan County, MO, Worth County, MO

The radar

The Quad Cities radar (KDVN), 105 km from the middle of the area, began a volume at 07:16 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

Davenport, (KDVN), launched 00:00Z, 7.3 hours before the alert went out and 106 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: 1056 J/kg
Mixed-layer CIN: -39 J/kg
Mixed-layer LCL: 1420 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: 100 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.7

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, 10:29 PM CDT	Mesoscale Discussion	SPC	Cook, DeKalb, DuPage, Ford, Grundy, Iroquois and 7 more	61 min
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, 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
May 4, 1:50 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Cherokee, Clay, Dickinson, Emmet, Ida and 7 more	25 min
May 4, 2:00 PM CDT	Severe Thunderstorm Watch	SPC	Buena Vista, Calhoun, Carroll, Cerro Gordo, Cherokee, Clay and 23 more	9 hr
May 4, 3:52 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Cerro Gordo, Cherokee, Clay, Dickinson, Emmet and 17 more	53 min
May 4, 5:31 PM CDT	Mesoscale Discussion	SPC	Audubon, Benton, Black Hawk, Boone, Bremer, Buchanan and 66 more	29 min
May 4, 5:52 PM CDT	Severe Thunderstorm Watch	SPC	Fremont, Harrison, Mills, Monona, Montgomery, Page and 2 more	5 hr
May 4, 6:01 PM CDT	Severe Thunderstorm Watch	SPC	Benton, Black Hawk, Boone, Bremer, Buchanan, Butler and 22 more	3 hr

Nearby

Mesoscale Discussions in Illinois, 2012 Mesoscale Discussions in Missouri, 2012 Mesoscale Discussions in Iowa, 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.