Alert archive / Illinois / Mesoscale Discussions in 2004
Mesoscale Discussion 405
The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2004, 11:10 PM CDT for 21 counties in Illinois; 15 counties in Missouri. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 20, 2004, 11:10 PM CDT (04:10 UTC)
- Expired
- Apr 21, 2004, 1:15 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
All 36 counties
Brown County, IL, Calhoun County, IL, Cass County, IL, Christian County, IL, Fulton County, IL, Greene County, IL, Jersey County, IL, Logan County, IL, Macoupin County, IL, Madison County, IL, Mason County, IL, Menard County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Pike County, IL, Saint Clair County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Tazewell County, IL, City of Saint Louis, MO, Crawford County, MO, Dent County, MO, Franklin County, MO, Gasconade County, MO, Iron County, MO, Jefferson County, MO, Lincoln County, MO, Phelps County, MO, Pike County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Warren County, MO, Washington County, MO
The nearest sounding before it
Lincoln, IL (KILX), launched 00:00Z, 4.2 hours before the alert went out and 210 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.
- Mixed-layer CAPE
- 118 J/kg
- Mixed-layer CIN
- -27 J/kg
- Mixed-layer LCL
- 1737 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 176 m²/s²
- 0-3 km storm-relative helicity
- 261 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.7
The text
As transmitted, in the capitals the NWS used until 2016.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 20, 8:55 PM CDT | Mesoscale Discussion | SPC | Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 13 more | 65 min |
| Apr 20, 9:38 PM CDT | Mesoscale Discussion | SPC | Calhoun | 37 min |
| Apr 21, 2:58 PM CDT | Mesoscale Discussion | SPC | Alexander, Edwards, Franklin, Gallatin, Hamilton, Jackson and 13 more | 92 min |
| Apr 20, 7:20 PM CDT | Mesoscale Discussion | SPC | Adair, Audrain, Bates, Benton, Boone, Caldwell and 38 more | 115 min |
| Apr 20, 7:22 PM CDT | Mesoscale Discussion | SPC | Barry, Barton, Cedar, Dade, Jasper, Lawrence and 4 more | 23 min |
| Apr 20, 7:50 PM CDT | Tornado Watch | SPC | Barry, McDonald, Stone, Taney | 5 hr |
| Apr 20, 8:06 PM CDT | Mesoscale Discussion | SPC | Atchison | 84 min |
| Apr 20, 8:57 PM CDT | Mesoscale Discussion | SPC | Barry, McDonald, Stone, Taney | 2 hr |
| Apr 20, 10:57 PM CDT | Mesoscale Discussion | SPC | Barry, McDonald, Stone, Taney | 93 min |
Nearby
Mesoscale Discussions in Illinois, 2004Mesoscale Discussions in Missouri, 2004Every mesoscale discussion in 2004
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.