Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1463
The Storm Prediction Center issued this mesoscale discussion at Aug 10, 2021, 2:20 PM CDT for 4 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 10, 2021, 2:20 PM CDT (19:20 UTC)
- Expired
- Aug 10, 2021, 4:45 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 46 counties
Alexander County, IL, Bond County, IL, Clay County, IL, Clinton County, IL, Edwards County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Jackson County, IL, Jefferson County, IL, Johnson County, IL, Marion County, IL, Massac County, IL, Monroe County, IL, Perry County, IL, Pope County, IL, Pulaski County, IL, Randolph County, IL, Saint Clair County, IL, Saline County, IL, Union County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Posey County, IN, Vanderburgh County, IN, Ballard County, KY, Carlisle County, KY, Crittenden County, KY, Henderson County, KY, Livingston County, KY, McCracken County, KY, Union County, KY, Webster County, KY, Bollinger County, MO, Cape Girardeau County, MO, Iron County, MO, Madison County, MO, Perry County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Scott County, MO, Washington County, MO
The radar
The Paducah radar (KPAH), 106 km from the middle of the area, began a volume at 19:20 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, 7.3 hours before the alert went out and 248 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
- 3933 J/kg
- Mixed-layer CIN
- -32 J/kg
- Mixed-layer LCL
- 851 m above ground
- 0-6 km bulk shear
- 11 kt
- 0-1 km storm-relative helicity
- -53 m²/s²
- 0-3 km storm-relative helicity
- -47 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
749
ACUS11 KWNS 101921
SWOMCD
SPC MCD 101920
INZ000-KYZ000-ILZ000-MOZ000-102145-
Mesoscale Discussion 1463
NWS Storm Prediction Center Norman OK
0220 PM CDT Tue Aug 10 2021
Areas affected...Portions of southeastern MO...southern IL...western
KY...and far southwestern IN
Concerning...Severe potential...Watch unlikely
Valid 101920Z - 102145Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated strong to damaging winds may continue for the
next few hours. Watch issuance appears unlikely at this time.
DISCUSSION...A small cluster of storms is ongoing this afternoon
near and south of the St. Louis metro area. This convection is
related to outflow from storms that occurred earlier today across
central/eastern MO. A wind gust to 35 kt was reported within the
past hour or so with this line at KSTL as it moved through, along
with isolated tree limb damage and small hail. This convection is
occurring well south of even modestly enhanced mid-level westerly
flow across the central Plains and upper MS Valley. But, it should
remain loosely organized along its own outflow, and it will
encounter a very unstable airmass with MLCAPE of 4000+ J/kg.
Accordingly, occasional strong to damaging wind gusts may continue
for the next few hours as the cluster moves slowly
east-southeastward into southern IL, southeastern MO, and perhaps
eventually western KY. Given the lack of stronger deep-layer shear,
expectations are for this cluster to exhibit only limited
organization. Accordingly, watch issuance appears unlikely at this
time.
..Gleason/Thompson.. 08/10/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PAH...ILX...LSX...
LAT...LON 38438778 38218745 37608757 36998815 36788898 37179050
37569102 37859114 38109065 38618996 38958977 38878867
38438778SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 9, 8:33 PM CDT | Mesoscale Discussion | SPC | Bureau, Knox, LaSalle, Livingston, Marshall, Peoria and 4 more | 87 min |
| Aug 10, 10:45 AM CDT | Mesoscale Discussion | SPC | Adams, Bond, Brown, Calhoun, Clinton, Greene and 9 more | 3 hr |
| Aug 10, 2:08 PM CDT | Severe Thunderstorm Watch | SPC | Henderson, Mercer, Rock Island, Warren | 6 hr |
| Aug 10, 3:10 PM CDT | Mesoscale Discussion | SPC | Boone, Carroll, DeKalb, Jo Daviess, Kane, Lake and 6 more | 2 hr |
| Aug 10, 3:47 PM CDT | Severe Thunderstorm Watch | SPC | Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 15 more | 6 hr |
| Aug 10, 5:51 PM CDT | Mesoscale Discussion | SPC | Boone, Carroll, DeKalb, DuPage, Jo Daviess, Kane and 7 more | 84 min |
Nearby
Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Missouri, 2021Mesoscale Discussions in Kentucky, 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.