Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1112
The Storm Prediction Center issued this mesoscale discussion at Jun 26, 2021, 2:47 PM CDT for 4 states. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Jun 26, 2021, 2:47 PM CDT (19:47 UTC)
- Expired
- Jun 26, 2021, 4:45 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 321
All 41 counties
Calhoun County, IL, DeWitt County, IL, Ford County, IL, Greene County, IL, Iroquois County, IL, Jersey County, IL, Kankakee County, IL, Livingston County, IL, Logan County, IL, Macoupin County, IL, McLean County, IL, Menard County, IL, Morgan County, IL, Sangamon County, IL, Elkhart County, IN, Jasper County, IN, Kosciusko County, IN, LaGrange County, IN, Lake County, IN, LaPorte County, IN, Marshall County, IN, Newton County, IN, Porter County, IN, Pulaski County, IN, Saint Joseph County, IN, Starke County, IN, Steuben County, IN, Branch County, MI, Calhoun County, MI, Cass County, MI, Eaton County, MI, Genesee County, MI, Hillsdale County, MI, Ingham County, MI, Jackson County, MI, Kalamazoo County, MI, Livingston County, MI, Saint Joseph County, MI, Shiawassee County, MI, Saint Charles County, MO, Saint Louis County, MO
The radar
The Chicago radar (KLOT), 88 km from the middle of the area, began a volume at 19:48 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 12:00Z, 7.8 hours before the alert went out and 119 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
- 683 J/kg
- Mixed-layer CIN
- -28 J/kg
- Mixed-layer LCL
- 684 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 263 m²/s²
- 0-3 km storm-relative helicity
- 229 m²/s²
- Significant tornado parameter
- 0.5
- Supercell composite
- 3.1
The text
As transmitted.
278
ACUS11 KWNS 261947
SWOMCD
SPC MCD 261947
MIZ000-INZ000-ILZ000-MOZ000-262145-
Mesoscale Discussion 1112
NWS Storm Prediction Center Norman OK
0247 PM CDT Sat Jun 26 2021
Areas affected...Parts of central/southern Lower
Michigan...northwestern Indiana...central Illinois...into east
central Missouri
Concerning...Tornado Watch 321...
Valid 261947Z - 262145Z
The severe weather threat for Tornado Watch 321 continues.
SUMMARY...More substantive thunderstorm intensification is ongoing
and likely to continue through late afternoon. Stronger storms will
continue to pose a risk for tornadoes, with organizing clusters also
posing a risk for damaging downbursts. Areas east and southwest of
Tornado Watch 321 are being monitored for the possibility of
additional watches.
DISCUSSION...A remnant convectively generated surface
boundary/deformation zone between a pair of MCV remains the primary
focus for deepening convective development and scattered vigorous
embedded thunderstorm activity. Boundary layer dewpoints are
increasing through the lower 70s F across interior southern Lower
Michigan, and remain in the mid 70s F southwest of Chicago into the
St. Louis area along this zone, where low-level hodographs also
remain sizable beneath a 30-40 kt south-southwesterly 850 mb jet.
The primary jet core now appears to be nosing into southern Lower
Michigan, but a secondary core appears to be currently migrating
across/northeast of the St. Louis area.
Despite weak lapse rates, the high boundary-layer moisture content
appears to be contributing to mixed-layer CAPE of 1500-2000 J/kg.
Coupled with the strong low-level vertical shear, the environment
appears to be coming increasingly conducive to strengthening
low-level mesocyclones within the stronger storms through late
afternoon. These may occasionally pose a risk for tornadoes and/or
strong downbursts.
..Kerr.. 06/26/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DTX...IWX...GRR...LOT...ILX...LSX...
LAT...LON 38819100 40059007 40948873 41378791 41568732 41818658
41978593 42848501 43268326 42138398 41268580 40588753
39648943 38529041 38819100SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 25, 7:05 PM CDT | Mesoscale Discussion | SPC | Iroquois, Kankakee, Vermilion | 55 min |
| Jun 25, 8:34 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Calhoun, Cass, Champaign, Christian and 30 more | 86 min |
| Jun 25, 10:31 PM CDT | Mesoscale Discussion | SPC | Bond, Calhoun, Cass, Champaign, Christian, Coles and 30 more | 59 min |
| Jun 26, 11:45 AM CDT | Mesoscale Discussion | SPC | Calhoun, Cass, Champaign, Christian, DeWitt, Ford and 21 more | 2 hr |
| Jun 26, 12:05 PM CDT | Tornado Watch | SPC | Cass, Champaign, Christian, Coles, Cook, Cumberland and 24 more | 9 hr |
| Jun 26, 6:08 PM CDT | Mesoscale Discussion | SPC | Champaign, Coles, Cumberland, Douglas, Edgar, Ford and 5 more | 67 min |
| Jun 26, 12:48 PM CDT | Mesoscale Discussion | SPC | LaPorte, Saint Joseph | 57 min |
| Jun 26, 6:47 PM CDT | Severe Thunderstorm Watch | SPC | Carroll, Clinton, Fountain, Montgomery, Parke, Tippecanoe and 2 more | 3 hr |
| Jun 26, 3:04 PM CDT | Tornado Watch | SPC | Arenac, Bay, Genesee, Gladwin, Huron, Iosco and 12 more | 6 hr |
Nearby
Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Indiana, 2021Mesoscale Discussions in Michigan, 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.