Alert archive / Missouri / Mesoscale Discussions in 2011

Mesoscale Discussion 466

April 18, 2011Calhoun County, Jersey County, Illinois; 18 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2011, 11:41 PM CDT for Calhoun County, Jersey County, Illinois; 18 counties in Missouri. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: Apr 18, 2011, 11:41 PM CDT (04:41 UTC)
Expired: Apr 19, 2011, 1:15 AM CDT
In force: 94 min
Issued by: the Storm Prediction Center

Counties Calhoun County, IL, Jersey County, IL, Audrain County, MO, Benton County, MO, Boone County, MO, Callaway County, MO, Cole County, MO, Cooper County, MO, Gasconade County, MO, Howard County, MO, Lincoln County, MO, Moniteau County, MO, Montgomery County, MO, Morgan County, MO, Osage County, MO, Pettis County, MO, Saint Charles County, MO, Saint Louis County, MO, Saline County, MO, Warren County, MO

The radar

The St Louis radar (KLSX), 88 km from the middle of the area, began a volume at 04:43 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.

Severe Thunderstorm Watch 153Apr 19, 3:15 AM CDT

The nearest sounding before it

Springfield, MO (KSGF), launched 00:00Z, 4.7 hours before the alert went out and 275 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: 554 J/kg
Mixed-layer CIN: -117 J/kg
Mixed-layer LCL: 1071 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 125 m²/s²
0-3 km storm-relative helicity: 259 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 3.1

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 19, 2:53 AM CDT	Mesoscale Discussion	SPC	Adams, Bond, Brown, Calhoun, Cass, Christian and 21 more	67 min
Apr 19, 3:11 AM CDT	Severe Thunderstorm Watch	SPC	Adams, Bond, Brown, Calhoun, Cass, Christian and 30 more	7 hr
Apr 19, 5:52 AM CDT	Mesoscale Discussion	SPC	Adams, Bond, Brown, Calhoun, Cass, Christian and 34 more	83 min
Apr 19, 8:29 AM CDT	Mesoscale Discussion	SPC	Christian, Clark, Coles, Crawford, Cumberland, Douglas and 8 more	61 min
Apr 19, 12:40 PM CDT	Mesoscale Discussion	SPC	Jersey, Madison, Monroe, Saint Clair	95 min
Apr 19, 1:00 PM CDT	Tornado Watch	SPC	Bond, Calhoun, Cass, Champaign, Christian, Clark and 36 more	10 hr
Apr 19, 5:47 PM CDT	Mesoscale Discussion	SPC	Bond, Calhoun, Christian, Clark, Clay, Clinton and 25 more	88 min
Apr 19, 6:24 PM CDT	Mesoscale Discussion	SPC	Alexander, Franklin, Jackson, Johnson, Pulaski, Saline and 2 more	66 min
Apr 19, 6:46 PM CDT	Tornado Watch	SPC	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more	9 hr

Nearby

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