Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1746
The Storm Prediction Center issued this mesoscale discussion at Sep 14, 2021, 3:18 PM CDT for 34 counties in Illinois; Benton County, Newton County, Warren County, Indiana; 28 counties in Missouri. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Sep 14, 2021, 3:18 PM CDT (20:18 UTC)
- Expired
- Sep 14, 2021, 5:15 PM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 65 counties
Bond County, IL, Calhoun County, IL, Champaign County, IL, Christian County, IL, Clinton County, IL, Coles County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Effingham County, IL, Fayette County, IL, Ford County, IL, Greene County, IL, Iroquois County, IL, Jersey County, IL, Kankakee County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, McLean County, IL, Menard County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Piatt County, IL, Saint Clair County, IL, Sangamon County, IL, Scott County, IL, Shelby County, IL, Vermilion County, IL, Benton County, IN, Newton County, IN, Warren County, IN, Barton County, MO, Benton County, MO, Callaway County, MO, Camden County, MO, Cedar County, MO, City of Saint Louis, MO, Cole County, MO, Crawford County, MO, Dade County, MO, Dallas County, MO, Franklin County, MO, Gasconade County, MO, Hickory County, MO, Jefferson County, MO, Lincoln County, MO, Maries County, MO, Miller County, MO, Moniteau County, MO, Montgomery County, MO, Morgan County, MO, Osage County, MO, Pike County, MO, Polk County, MO, Saint Charles County, MO, Saint Louis County, MO, St. Clair County, MO, Vernon County, MO, Warren County, MO
The radar
The St Louis radar (KLSX), 68 km from the middle of the area, began a volume at 20:22 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, 8.3 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.
- Mixed-layer CAPE
- 1485 J/kg
- Mixed-layer CIN
- -96 J/kg
- Mixed-layer LCL
- 988 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 207 m²/s²
- 0-3 km storm-relative helicity
- 165 m²/s²
- Significant tornado parameter
- 0.7
- Supercell composite
- 6.6
The text
As transmitted.
332
ACUS11 KWNS 142018
SWOMCD
SPC MCD 142018
INZ000-ILZ000-MOZ000-142215-
Mesoscale Discussion 1746
NWS Storm Prediction Center Norman OK
0318 PM CDT Tue Sep 14 2021
Areas affected...Central Missouri into Central Illinois
Concerning...Severe potential...Watch unlikely
Valid 142018Z - 142215Z
Probability of Watch Issuance...20 percent
SUMMARY...Storm coverage will increase along the cold front into
early evening. Damaging wind gusts will be the primary threat with
large hail being more isolated. A watch is not expected, though
trends will be monitored.
DISCUSSION...Strong surface heating along the cold front has
produced a deepening field of cumulus and isolated thunderstorms in
central Missouri into central Illinois. Some additional, modest
mid-level ascent, primarily focused in Illinois, could promote
additional development later this afternoon. Deep-layer shear in the
warm sector is weak and should generally remain near 25 kts. The
strongest storms will be capable of damaging wind gusts and perhaps
isolated large hail. Should storms congeal, a more organized
damaging wind threat would develop. Lack of greater shear and
mid-level forcing will likely keep the threat marginal. Trends will
be monitored, but no watch is expected this afternoon.
..Wendt/Thompson.. 09/14/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...IND...LOT...ILX...LSX...SGF...EAX...
LAT...LON 40798886 41308766 40858724 40548712 39408773 38818877
37989086 37879228 37329423 37569453 38119445 38989215
39499079 40798886SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 14, 1:12 PM CDT | Mesoscale Discussion | SPC | Allen, DeKalb, Elkhart, Fulton, Huntington, Kosciusko and 9 more | 2 hr |
| Sep 14, 2:08 PM CDT | Severe Thunderstorm Watch | SPC | Allen, Blackford, Cass, DeKalb, Elkhart, Fulton and 16 more | 7 hr |
| Sep 14, 5:04 PM CDT | Mesoscale Discussion | SPC | Adams, Allen, Blackford, Carroll, Cass, DeKalb and 15 more | 86 min |
| Sep 14, 6:46 PM CDT | Mesoscale Discussion | SPC | Adams, Allen, Blackford, DeKalb, Delaware, Grant and 8 more | 89 min |
Nearby
Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Missouri, 2021Mesoscale Discussions in Indiana, 2021Every mesoscale discussion in 2021
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.