Alert archive / Missouri / Mesoscale Discussions in 2008

Mesoscale Discussion 1845

July 21, 200812 counties in Illinois; Appanoose County, Decatur County, Wayne County, Iowa; 14 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2008, 7:16 PM CDT for 12 counties in Illinois; Appanoose County, Decatur County, Wayne County, Iowa; 14 counties in Missouri. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Jul 21, 2008, 7:16 PM CDT (00:16 UTC)
Expired: Jul 21, 2008, 8:45 PM CDT
In force: 89 min
Issued by: the Storm Prediction Center

All 29 counties

Appanoose County, IA, Decatur County, IA, Wayne County, IA, Adams County, IL, Brown County, IL, Cass County, IL, Fulton County, IL, Hancock County, IL, Mason County, IL, McDonough County, IL, Menard County, IL, Morgan County, IL, Pike County, IL, Schuyler County, IL, Scott County, IL, Adair County, MO, Clark County, MO, Grundy County, MO, Harrison County, MO, Knox County, MO, Lewis County, MO, Macon County, MO, Marion County, MO, Mercer County, MO, Putnam County, MO, Schuyler County, MO, Scotland County, MO, Shelby County, MO, Sullivan County, MO

The radar

The Quad Cities radar (KDVN), 177 km from the middle of the area, began a volume at 00:18 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 720Jul 21, 7:20 PM CDT

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 0.3 hours before the alert went out and 182 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: 721 J/kg
Mixed-layer CIN: -258 J/kg
Mixed-layer LCL: 1280 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 102 m²/s²
0-3 km storm-relative helicity: 143 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

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
Jul 21, 7:20 PM CDT	Severe Thunderstorm Watch	SPC	Cass, Champaign, Christian, Clark, Coles, Cumberland and 26 more	7 hr
Jul 21, 8:00 PM CDT	Mesoscale Discussion	SPC	Bond, Calhoun, Christian, Clay, Clinton, Effingham and 12 more	90 min
Jul 21, 9:14 PM CDT	Severe Thunderstorm Watch	SPC	Bond, Calhoun, Clay, Clinton, Crawford, Edwards and 22 more	6 hr
Jul 21, 10:38 PM CDT	Mesoscale Discussion	SPC	Bond, Calhoun, Christian, Clark, Clay, Clinton and 32 more	97 min
Jul 22, 4:47 AM CDT	Mesoscale Discussion	SPC	Alexander, Hardin, Jackson, Johnson, Massac, Pope and 5 more	88 min
Jul 22, 3:18 AM CDT	Mesoscale Discussion	SPC	Fremont, Mills, Montgomery, Page, Pottawattamie, Taylor	87 min
Jul 22, 9:34 AM CDT	Mesoscale Discussion	SPC	Boone, Camden, Cole, Cooper, Crawford, Dent and 12 more	56 min
Jul 22, 11:55 AM CDT	Mesoscale Discussion	SPC	Dunklin, Pemiscot	3 hr
Jul 22, 2:25 PM CDT	Mesoscale Discussion	SPC	Barry, Butler, Carter, Howell, Jasper, McDonald and 7 more	2 hr

Nearby

Mesoscale Discussions in Missouri, 2008 Mesoscale Discussions in Illinois, 2008 Mesoscale Discussions in Iowa, 2008 Every mesoscale discussion in 2008

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.