Alert archive / Illinois / Mesoscale Discussions in 2018
Mesoscale Discussion 1329
The Storm Prediction Center issued this mesoscale discussion at Aug 20, 2018, 4:46 PM CDT for 17 counties in Illinois; Dubuque County, Jackson County, Iowa; 4 counties in Wisconsin. It was in force for 119 min.
The area
The outline as issued.
The facts
- Issued
- Aug 20, 2018, 4:46 PM CDT (21:46 UTC)
- Expired
- Aug 20, 2018, 6:45 PM CDT
- In force
- 119 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 23 counties
Dubuque County, IA, Jackson County, IA, Boone County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Grundy County, IL, Jo Daviess County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Stephenson County, IL, Will County, IL, Winnebago County, IL, Green County, WI, Lafayette County, WI, Rock County, WI, Walworth County, WI
The radar
The Chicago radar (KLOT), 111 km from the middle of the area, began a volume at 21:44 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 12:00Z, 9.8 hours before the alert went out and 214 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
- 367 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 470 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 166 m²/s²
- 0-3 km storm-relative helicity
- 158 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.4
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 |
|---|---|---|---|---|
| Aug 20, 11:46 AM CDT | Mesoscale Discussion | SPC | Alexander, Bond, Clay, Clinton, Franklin, Hamilton and 17 more | 119 min |
| Aug 20, 12:46 PM CDT | Severe Thunderstorm Watch | SPC | Alexander, Clinton, Edwards, Franklin, Hamilton, Jackson and 16 more | 7 hr |
| Aug 20, 4:00 PM CDT | Mesoscale Discussion | SPC | Alexander, Clinton, Edwards, Franklin, Gallatin, Hamilton and 14 more | 2 hr |
| Aug 20, 4:45 PM CDT | Severe Thunderstorm Watch | SPC | Gallatin, Hardin, Massac, Pope | 6 hr |
Nearby
Mesoscale Discussions in Illinois, 2018Mesoscale Discussions in Wisconsin, 2018Mesoscale Discussions in Iowa, 2018Every mesoscale discussion in 2018
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.