Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1041
The Storm Prediction Center issued this mesoscale discussion at Jun 20, 2021, 9:54 PM CDT for 31 counties in Illinois; Monroe County, Ralls County, Missouri. It was in force for 66 min.
The area
The outline as issued.
The facts
- Issued
- Jun 20, 2021, 9:54 PM CDT (02:54 UTC)
- Expired
- Jun 20, 2021, 11:00 PM CDT
- In force
- 66 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 296
All 33 counties
Adams County, IL, Boone County, IL, Brown County, IL, Bureau County, IL, Carroll County, IL, Cass County, IL, DeKalb County, IL, Fulton County, IL, Henry County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Logan County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, Menard County, IL, Morgan County, IL, Ogle County, IL, Peoria County, IL, Pike County, IL, Putnam County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Whiteside County, IL, Winnebago County, IL, Woodford County, IL, Monroe County, MO, Ralls County, MO
The radar
The Lincoln radar (KILX), 106 km from the middle of the area, began a volume at 02:55 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
Davenport, (KDVN), launched 00:00Z, 2.9 hours before the alert went out and 122 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
- 1058 J/kg
- Mixed-layer CIN
- -19 J/kg
- Mixed-layer LCL
- 1009 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km storm-relative helicity
- 174 m²/s²
- 0-3 km storm-relative helicity
- 230 m²/s²
- Significant tornado parameter
- 1.4
- Supercell composite
- 7.8
The text
As transmitted.
469
ACUS11 KWNS 210255
SWOMCD
SPC MCD 210254
ILZ000-IAZ000-MOZ000-210400-
Mesoscale Discussion 1041
NWS Storm Prediction Center Norman OK
0954 PM CDT Sun Jun 20 2021
Areas affected...West-central/northern IL...northeast MO
Concerning...Severe Thunderstorm Watch 296...
Valid 210254Z - 210400Z
The severe weather threat for Severe Thunderstorm Watch 296
continues.
SUMMARY...The potential for damaging winds, large hail and a tornado
or two will continue across the watch area.
DISCUSSION...Regional radar composite as of 0245z depicts several
areas of strong/severe thunderstorms across or about to enter WW
296. Coverage continues to increase as warm advection with an
intensifying low-level jet focuses ascent across the watch area.
Latest SPC mesoanalysis shows a supportive environment for a
continued severe risk with strong instability (2000-2500 J/kg) and
35-40 kts of westerly effective shear. Although individual cells
will be capable of severe hail, cells merging into clusters/line
segments will be capable of producing more concentrated areas of
damaging winds and perhaps a brief tornado.
..Bunting.. 06/21/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LOT...ILX...LSX...DVN...
LAT...LON 39529033 39459092 39349177 39369216 39529223 39929140
40219091 41089043 41759018 42329010 42438948 42348882
41508861 39648959 39529033SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 20, 8:10 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Boone, Brown, Bureau, Calhoun, Carroll and 31 more | 5 hr |
| Jun 20, 9:40 PM CDT | Severe Thunderstorm Watch | SPC | Cook, DuPage, Ford, Grundy, Iroquois, Kane and 6 more | 4 hr |
| Jun 20, 9:56 PM CDT | Mesoscale Discussion | SPC | Bates, Cass, Cooper, Henry, Johnson, Lafayette and 2 more | 64 min |
| Jun 21, 11:35 AM CDT | Mesoscale Discussion | SPC | Dunklin, Pemiscot | 85 min |
Nearby
Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Missouri, 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.