Alert archive / Illinois / Mesoscale Discussions in 2015

Mesoscale Discussion 237

April 8, 201513 counties in Illinois; 6 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Apr 8, 2015, 3:42 PM CDT for 13 counties in Illinois; 6 counties in Missouri. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued: Apr 8, 2015, 3:42 PM CDT (20:42 UTC)
Expired: Apr 8, 2015, 4:45 PM CDT
In force: 63 min
Issued by: the Storm Prediction Center

Counties Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Jackson County, IL, Jefferson County, IL, Monroe County, IL, Perry County, IL, Randolph County, IL, Saint Clair County, IL, Saline County, IL, Washington County, IL, White County, IL, Williamson County, IL, Iron County, MO, Jefferson County, MO, Perry County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 122 km from the middle of the area, began a volume at 20:43 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 37Apr 8, 4:05 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 8.7 hours before the alert went out and 247 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: 195 J/kg
Mixed-layer CIN: -238 J/kg
Mixed-layer LCL: 839 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 66 m²/s²
0-3 km storm-relative helicity: 142 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 7.7

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
Apr 8, 7:41 AM CDT	Mesoscale Discussion	SPC	Clark, Coles, Cumberland	64 min
Apr 8, 12:01 PM CDT	Mesoscale Discussion	SPC	Jackson, Monroe, Perry, Randolph, Saint Clair, Washington	59 min
Apr 8, 12:50 PM CDT	Mesoscale Discussion	SPC	Bond, Calhoun, Champaign, Christian, Clark, Clay and 32 more	85 min
Apr 8, 1:05 PM CDT	Severe Thunderstorm Watch	SPC	Bond, Calhoun, Champaign, Christian, Clark, Clay and 42 more	5 hr
Apr 8, 2:43 PM CDT	Mesoscale Discussion	SPC	Bond, Brown, Calhoun, Cass, Champaign, Christian and 45 more	92 min
Apr 8, 4:07 PM CDT	Tornado Watch	SPC	Edwards, Franklin, Gallatin, Hamilton, Hardin, Jackson and 13 more	4 hr
Apr 7, 8:24 PM CDT	Severe Thunderstorm Watch	SPC	Barton, Bates, Benton, Cass, Cedar, Cooper and 13 more	5 hr
Apr 7, 10:13 PM CDT	Mesoscale Discussion	SPC	Barton, Bates, Benton, Cass, Cedar, Henry and 6 more	2 hr
Apr 8, 6:17 AM CDT	Mesoscale Discussion	SPC	Bates, Benton, Boone, Callaway, Camden, Cass and 19 more	88 min
Apr 8, 6:39 AM CDT	Severe Thunderstorm Watch	SPC	Adair, Audrain, Barton, Bates, Benton, Boone and 54 more	6 hr
Apr 8, 9:33 AM CDT	Mesoscale Discussion	SPC	Adair, Audrain, Benton, Boone, Caldwell, Callaway and 45 more	57 min
Apr 8, 2:21 PM CDT	Mesoscale Discussion	SPC	Barry, Barton, Bates, Benton, Camden, Cass and 16 more	114 min
Apr 8, 2:47 PM CDT	Severe Thunderstorm Watch	SPC	Barry, Barton, Bates, Benton, Camden, Cass and 29 more	4 hr
Apr 8, 5:45 PM CDT	Mesoscale Discussion	SPC	Audrain, Bates, Benton, Boone, Caldwell, Callaway and 39 more	60 min

Nearby

Mesoscale Discussions in Illinois, 2015 Mesoscale Discussions in Missouri, 2015 Every mesoscale discussion in 2015

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.