Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1472
The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2021, 6:26 AM CDT for 18 counties in Illinois; Des Moines County, Lee County, Iowa; 6 counties in Missouri. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 11, 2021, 6:26 AM CDT (11:26 UTC)
- Expired
- Aug 11, 2021, 8:30 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 26 counties
Des Moines County, IA, Lee County, IA, Adams County, IL, Brown County, IL, Cass County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Knox County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, Mercer County, IL, Peoria County, IL, Schuyler County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL, Woodford County, IL, Clark County, MO, Knox County, MO, Lewis County, MO, Marion County, MO, Scotland County, MO, Shelby County, MO
The radar
The Quad Cities radar (KDVN), 112 km from the middle of the area, began a volume at 11:28 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, 11.4 hours before the alert went out and 114 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
- 856 J/kg
- Mixed-layer CIN
- -155 J/kg
- Mixed-layer LCL
- 940 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 77 m²/s²
- 0-3 km storm-relative helicity
- 160 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -1.4
The text
As transmitted.
062
ACUS11 KWNS 111126
SWOMCD
SPC MCD 111126
ILZ000-IAZ000-MOZ000-111330-
Mesoscale Discussion 1472
NWS Storm Prediction Center Norman OK
0626 AM CDT Wed Aug 11 2021
Areas affected...Far Northeast MO...Extreme Southeast
IA...West-Central IL
Concerning...Severe potential...Watch unlikely
Valid 111126Z - 111330Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated large hail and/or a few damaging wind gusts
possible over the next few hours.
DISCUSSION...Cluster of thunderstorms across far northeast MO and
extreme southeast IA has gradually intensified over the past hour.
This activity currently appears to be rooted in the 850 mb to 700 mb
layer. The downstream air mass is characterized by steep mid-level
lapse rates and strong buoyancy, suggesting the ongoing cluster will
likely be maintained in the short-term. Estimated storm motion takes
these storms across west-central IL over the next two hours. Given
the prevailing low-level stability, the primary severe threat will
be large hail. However, a few strong gust may be able to penetrate
this low-level stable layer, especially with eastern extent where
greater low-level moisture currently exists. Overall severe coverage
is uncertain, precluding higher watch probabilities. However,
convective trends are being monitored closely.
..Mosier/Guyer.. 08/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ILX...LSX...DVN...EAX...
LAT...LON 40479218 41219108 41588989 41238938 40538906 39849031
39679257 40479218SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 10, 7:38 PM CDT | Severe Thunderstorm Watch | SPC | Kankakee | 5 hr |
| Aug 11, 1:20 AM CDT | Mesoscale Discussion | SPC | Bureau, Ford, Fulton, Grundy, Henry, Iroquois and 15 more | 115 min |
| Aug 11, 4:49 AM CDT | Mesoscale Discussion | SPC | Adams | 86 min |
| Aug 11, 8:34 AM CDT | Mesoscale Discussion | SPC | Bureau, Cook, DeKalb, DuPage, Ford, Grundy and 13 more | 86 min |
| Aug 11, 8:52 AM CDT | Severe Thunderstorm Watch | SPC | Cook, DeKalb, DuPage, Grundy, Kane, Kankakee and 6 more | 4 hr |
| Aug 11, 9:52 AM CDT | Mesoscale Discussion | SPC | Cook, DuPage, Grundy, Kane, Kankakee, Lake and 1 more | 83 min |
| Aug 11, 3:56 PM CDT | Mesoscale Discussion | SPC | Carroll, Hancock, Henderson, Henry, Jo Daviess, Mercer and 2 more | 3 hr |
| Aug 11, 5:40 PM CDT | Mesoscale Discussion | SPC | Carroll, Jo Daviess, Stephenson | 95 min |
| Aug 11, 11:48 AM CDT | Mesoscale Discussion | SPC | Allamakee | 117 min |
| Aug 11, 12:17 PM CDT | Tornado Watch | SPC | Allamakee, Clayton | 8 hr |
Nearby
Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Missouri, 2021Mesoscale Discussions in Iowa, 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.