Alert archive / Illinois / Mesoscale Discussions in 2020
Mesoscale Discussion 496
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2020, 9:06 PM CDT for 21 counties in Illinois; 19 counties in Missouri. It was in force for 84 min.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2020, 9:06 PM CDT (02:06 UTC)
- Expired
- Apr 28, 2020, 10:30 PM CDT
- In force
- 84 min
- Issued by
- the Storm Prediction Center
All 40 counties
Bond County, IL, Christian County, IL, Clinton County, IL, Coles County, IL, Cumberland County, IL, Douglas County, IL, Effingham County, IL, Fayette County, IL, Jersey County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Moultrie County, IL, Piatt County, IL, Randolph County, IL, Saint Clair County, IL, Shelby County, IL, Washington County, IL, City of Saint Louis, MO, Crawford County, MO, Dent County, MO, Douglas County, MO, Franklin County, MO, Howell County, MO, Iron County, MO, Jefferson County, MO, Madison County, MO, Oregon County, MO, Ozark County, MO, Reynolds County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Shannon County, MO, Texas County, MO, Washington County, MO
The radar
The St Louis radar (KLSX), 74 km from the middle of the area, began a volume at 02:07 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, 2.1 hours before the alert went out and 290 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
- 549 J/kg
- Mixed-layer CIN
- -34 J/kg
- Mixed-layer LCL
- 1190 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 132 m²/s²
- 0-3 km storm-relative helicity
- 196 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 4.6
The text
As transmitted.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 28, 7:35 PM CDT | Severe Thunderstorm Watch | SPC | Alexander, Franklin, Jackson, Jefferson, Johnson, Massac and 4 more | 7 hr |
| Apr 28, 11:12 PM CDT | Mesoscale Discussion | SPC | Hardin, Johnson, Massac, Pope, Pulaski | 63 min |
| Apr 28, 7:20 PM CDT | Mesoscale Discussion | SPC | Greene, Webster, Wright | 25 min |
Nearby
Mesoscale Discussions in Illinois, 2020Mesoscale Discussions in Missouri, 2020Every mesoscale discussion in 2020
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.