Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1996
The Storm Prediction Center issued this mesoscale discussion at Dec 10, 2021, 8:53 PM CST for 27 counties in Illinois. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Dec 10, 2021, 8:53 PM CST (02:53 UTC)
- Expired
- Dec 10, 2021, 10:30 PM CST
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 552...553...557
All 27 counties
Bond County, IL, Champaign County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Effingham County, IL, Fayette County, IL, Ford County, IL, Jasper County, IL, Logan County, IL, Macon County, IL, Madison County, IL, Marion County, IL, McLean County, IL, Montgomery County, IL, Moultrie County, IL, Piatt County, IL, Richland County, IL, Sangamon County, IL, Shelby County, IL, Vermilion County, IL
The radar
The Lincoln radar (KILX), 98 km from the middle of the area, began a volume at 02:56 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.
The nearest sounding before it
Lincoln, IL (KILX), launched 00:00Z, 2.9 hours before the alert went out and 74 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
- 119 J/kg
- Mixed-layer CIN
- -33 J/kg
- Mixed-layer LCL
- 662 m above ground
- 0-6 km bulk shear
- 73 kt
- 0-1 km storm-relative helicity
- 341 m²/s²
- 0-3 km storm-relative helicity
- 357 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
314
ACUS11 KWNS 110253
SWOMCD
SPC MCD 110253
ILZ000-110430-
Mesoscale Discussion 1996
NWS Storm Prediction Center Norman OK
0853 PM CST Fri Dec 10 2021
Areas affected...portions of central into southern IL
Concerning...Tornado Watch 552...553...557...
Valid 110253Z - 110430Z
The severe weather threat for Tornado Watch 552, 553, 557 continues.
SUMMARY...The severe threat continues across Tornado Watches 552,
553 and 557. A locally higher tornado threat may evolve with a more
dominant storm at the southern end of a line of storms.
DISCUSSION...Multiple linear thunderstorm segments with embedded
supercell structures have recently congealed into a more coherent
squall-line structure across central and southern Illinois. Storms
within this squall have a history of producing damaging gusts over
70 mph as well as isolated tornadoes. Widespread 60F dewpoints
overspread by 6-7 C/km mid-level lapse rates are contributing to
1000 J/kg MLCAPE per 02Z mesoanalysis, amid minimal convective
inhibition. The latest mesoanalysis shows widespread effective bulk
shear exceeding 80 kts with ILX and PAH VWPs depicting long, curved
hodographs (contributing to 300-500 0-1 km SRH). Given the
impressive shear profiles, damaging gusts and tornadoes will remain
a concern for at least a few more hours.
At the southern end of the line, more dominant supercell structures
have produced TDSs, and are progressing across an unimpeded
low-level airmass, characterized by mid 60s F dewpoints. The
impressive low-level shear, adequate moisture, and open warm sector
may support a locally higher tornado threat with these storms, and a
strong tornado is possible.
..Squitieri/Grams.. 12/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LOT...ILX...LSX...
LAT...LON 38718789 38698825 38638893 38668938 38728965 38858997
39538981 40518931 40748889 40878829 40708780 40308756
39638762 38968771 38718789SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 10, 7:02 PM CST | Mesoscale Discussion | SPC | Calhoun, Greene, Jersey, Macoupin, Madison, Monroe and 4 more | 58 min |
| Dec 10, 7:18 PM CST | Mesoscale Discussion | SPC | Champaign, Christian, Clark, Clay, Coles, Crawford and 18 more | 87 min |
| Dec 10, 7:47 PM CST | Tornado Watch | SPC | Champaign, Clark, Clay, Coles, Crawford, Cumberland and 21 more | 8 hr |
| Dec 10, 9:36 PM CST | Mesoscale Discussion | SPC | Clark, Coles, Cumberland, Edgar, Effingham, Shelby | 54 min |
| Dec 10, 10:09 PM CST | Mesoscale Discussion | SPC | Massac | 96 min |
| Dec 10, 11:03 PM CST | Tornado Watch | SPC | Alexander, Clinton, Edwards, Fayette, Franklin, Gallatin and 17 more | 5 hr |
| Dec 10, 11:28 PM CST | Mesoscale Discussion | SPC | Alexander, Clark, Clay, Coles, Crawford, Cumberland and 24 more | 92 min |
Nearby
Mesoscale Discussions in Illinois, 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.