Alert archive / Illinois / Mesoscale Discussions in 2006

Mesoscale Discussion 1839

August 18, 200613 counties in Illinois; 4 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Aug 18, 2006, 10:15 PM CDT for 13 counties in Illinois; 4 counties in Missouri. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued: Aug 18, 2006, 10:15 PM CDT (03:15 UTC)
Expired: Aug 18, 2006, 11:15 PM CDT
In force: 60 min
Issued by: the Storm Prediction Center

Counties Bond County, IL, Christian County, IL, Clay County, IL, Clinton County, IL, Cumberland County, IL, Effingham County, IL, Fayette County, IL, Jasper County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Montgomery County, IL, Shelby County, IL, City of Saint Louis, MO, Saint Charles County, MO, Saint Louis County, MO, Warren County, MO

The radar

The St Louis radar (KLSX), 89 km from the middle of the area, began a volume at 03:19 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 nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 3.3 hours before the alert went out and 160 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: 1245 J/kg
Mixed-layer CIN: -86 J/kg
Mixed-layer LCL: 1180 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 6 m²/s²
0-3 km storm-relative helicity: 28 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

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
Aug 18, 7:41 PM CDT	Severe Thunderstorm Watch	SPC	Bond, Calhoun, Clinton, Fayette, Greene, Jersey 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.