Alert archive / Illinois / Mesoscale Discussions in 2015

Mesoscale Discussion 214

April 7, 201517 counties in Illinois; 9 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Apr 7, 2015, 8:17 AM CDT for 17 counties in Illinois; 9 counties in Missouri. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Apr 7, 2015, 8:17 AM CDT (13:17 UTC)
Expired: Apr 7, 2015, 9:45 AM CDT
In force: 88 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 26 counties

Bond County, IL, Clinton County, IL, Franklin County, IL, Hamilton County, IL, Jackson County, IL, Jefferson County, IL, Johnson County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Perry County, IL, Randolph County, IL, Saint Clair County, IL, Saline County, IL, Union County, IL, Washington County, IL, Williamson County, IL, City of Saint Louis, MO, Franklin County, MO, Jefferson County, MO, Perry County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 90 km from the middle of the area, began a volume at 13:19 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 27Apr 7, 8:35 AM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 1.3 hours before the alert went out and 242 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: 134 J/kg
Mixed-layer CIN: -199 J/kg
Mixed-layer LCL: 443 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 23 m²/s²
0-3 km storm-relative helicity: 87 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 7, 8:34 AM CDT	Severe Thunderstorm Watch	SPC	Clinton, Franklin, Jackson, Jefferson, Johnson, Madison and 7 more	7 hr
Apr 7, 10:51 AM CDT	Mesoscale Discussion	SPC	Franklin, Gallatin, Hamilton, Hardin, Jackson, Jefferson and 11 more	54 min
Apr 7, 1:14 PM CDT	Mesoscale Discussion	SPC	Edwards, Franklin, Gallatin, Hamilton, Hardin, Jackson and 7 more	61 min
Apr 7, 1:37 PM CDT	Severe Thunderstorm Watch	SPC	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 10 more	5 hr
Apr 7, 2:53 PM CDT	Mesoscale Discussion	SPC	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 14 more	97 min
Apr 7, 3:51 AM CDT	Mesoscale Discussion	SPC	Audrain, Boone, Caldwell, Carroll, Chariton, Daviess and 9 more	54 min
Apr 7, 5:03 PM CDT	Mesoscale Discussion	SPC	Barton, Bates, Cass, Cedar, Dade, Greene and 9 more	2 hr

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.