Alert archive / Illinois / Mesoscale Discussions in 2011

Mesoscale Discussion 1591

July 12, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Jul 12, 2011, 1:00 PM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 12, 2011, 1:00 PM CDT (18:00 UTC)
Expired: Jul 12, 2011, 3:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 83 counties

Des Moines County, IA, Lee County, IA, Adams County, IL, Bond County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Fulton County, IL, Gallatin County, IL, Greene County, IL, Hamilton County, IL, Hancock County, IL, Henderson County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Jersey County, IL, Lawrence County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Mason County, IL, McDonough County, IL, Menard County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Perry County, IL, Piatt County, IL, Pike County, IL, Randolph County, IL, Richland County, IL, Saint Clair County, IL, Saline County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Shelby County, IL, Tazewell County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Gibson County, IN, Knox County, IN, Posey County, IN, Audrain County, MO, City of Saint Louis, MO, Clark County, MO, Franklin County, MO, Jefferson County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Macon County, MO, Marion County, MO, Monroe County, MO, Montgomery County, MO, Pike County, MO, Ralls County, MO, Randolph County, MO, Saint Charles County, MO, Saint Louis County, MO, Shelby County, MO, Warren County, MO

The radar

The St Louis radar (KLSX), 87 km from the middle of the area, began a volume at 18:05 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 636Jul 12, 1:45 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 6.0 hours before the alert went out and 157 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: 1615 J/kg
Mixed-layer CIN: -167 J/kg
Mixed-layer LCL: 777 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: -4 m²/s²
0-3 km storm-relative helicity: -14 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
Jul 12, 1:45 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Bond, Brown, Calhoun, Cass, Christian and 49 more	7 hr
Jul 12, 3:48 PM CDT	Mesoscale Discussion	SPC	Adams, Bond, Brown, Calhoun, Cass, Christian and 38 more	87 min
Jul 12, 6:43 PM CDT	Mesoscale Discussion	SPC	Adams, Bond, Brown, Calhoun, Christian, Clark and 41 more	62 min
Jul 11, 8:22 PM CDT	Severe Thunderstorm Watch	SPC	Dearborn, Fayette, Franklin, Ohio, Ripley, Switzerland and 2 more	3 hr
Jul 12, 2:09 AM CDT	Mesoscale Discussion	SPC	Audubon, Buena Vista, Carroll, Cass, Cherokee, Crawford and 11 more	66 min
Jul 12, 4:33 PM CDT	Mesoscale Discussion	SPC	Barton, Bates, Benton, Buchanan, Camden, Cass and 26 more	87 min

Nearby

Mesoscale Discussions in Illinois, 2011 Mesoscale Discussions in Missouri, 2011 Mesoscale Discussions in Indiana, 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.