Alert archive / Illinois / Mesoscale Discussions in 2006

Mesoscale Discussion 554

April 19, 200629 counties in Illinois; 9 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Apr 19, 2006, 12:00 AM CDT for 29 counties in Illinois; 9 counties in Missouri. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued: Apr 19, 2006, 12:00 AM CDT (05:00 UTC)
Expired: Apr 19, 2006, 1:00 AM CDT
In force: 60 min
Issued by: the Storm Prediction Center

All 38 counties

Alexander County, IL, Bond County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Crawford County, IL, Cumberland County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Hamilton County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Perry County, IL, Randolph County, IL, Richland County, IL, Saint Clair County, IL, Saline County, IL, Shelby County, IL, Union County, IL, Washington County, IL, Wayne County, IL, Williamson County, IL, Bollinger County, MO, Cape Girardeau County, MO, City of Saint Louis, MO, Jefferson County, MO, Madison County, MO, Perry County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Wayne County, MO

The radar

The St Louis radar (KLSX), 120 km from the middle of the area, began a volume at 05:00 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.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 5.0 hours before the alert went out and 234 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1825 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 64 m²/s²
0-3 km storm-relative helicity: 276 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.7

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 18, 8:59 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Calhoun, Cass, Greene, Hancock and 11 more	91 min
Apr 18, 9:15 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Brown, Calhoun, Cass, Greene, Hancock and 7 more	4 hr
Apr 18, 9:27 PM CDT	Tornado Watch	SPC	Alexander, Jackson, Madison, Monroe, Perry, Pulaski and 3 more	6 hr
Apr 18, 10:36 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Calhoun, Cass, Fulton, Greene and 18 more	114 min
Apr 19, 12:50 AM CDT	Severe Thunderstorm Watch	SPC	Champaign, Clark, Clay, Coles, Crawford, Cumberland and 13 more	6 hr
Apr 19, 1:29 AM CDT	Tornado Watch	SPC	Edwards, Franklin, Gallatin, Hamilton, Hardin, Jefferson and 8 more	4 hr

Nearby

Mesoscale Discussions in Illinois, 2006 Mesoscale Discussions in Missouri, 2006 Every mesoscale discussion in 2006

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.