Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1897
The Storm Prediction Center issued this mesoscale discussion at Oct 24, 2021, 10:33 PM CDT for 37 counties in Illinois; 15 counties in Missouri. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 24, 2021, 10:33 PM CDT (03:33 UTC)
- Expired
- Oct 25, 2021, 1:00 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 533
All 52 counties
Alexander County, IL, Bond County, IL, Champaign County, IL, Christian County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Hamilton County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Johnson County, IL, Logan County, IL, Macon County, IL, Marion County, IL, Mason County, IL, Menard County, IL, Montgomery County, IL, Moultrie County, IL, Perry County, IL, Piatt County, IL, Pulaski County, IL, Randolph County, IL, Saint Clair County, IL, Saline County, IL, Sangamon County, IL, Shelby County, IL, Union County, IL, Washington County, IL, Wayne County, IL, Williamson County, IL, Bollinger County, MO, Butler County, MO, Cape Girardeau County, MO, Carter County, MO, Iron County, MO, Madison County, MO, Oregon County, MO, Perry County, MO, Reynolds County, MO, Ripley County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Scott County, MO, Stoddard County, MO, Wayne County, MO
The radar
The St Louis radar (KLSX), 120 km from the middle of the area, began a volume at 03:33 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 00:00Z, 3.6 hours before the alert went out and 179 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
- 3 J/kg
- Mixed-layer CIN
- -286 J/kg
- Mixed-layer LCL
- 585 m above ground
- 0-6 km bulk shear
- 64 kt
- 0-1 km storm-relative helicity
- 371 m²/s²
- 0-3 km storm-relative helicity
- 467 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 4.1
The text
As transmitted.
934
ACUS11 KWNS 250333
SWOMCD
SPC MCD 250333
ILZ000-KYZ000-MOZ000-250600-
Mesoscale Discussion 1897
NWS Storm Prediction Center Norman OK
1033 PM CDT Sun Oct 24 2021
Areas affected...southeast Missouri...central and southern Illinois
Concerning...Tornado Watch 533...
Valid 250333Z - 250600Z
The severe weather threat for Tornado Watch 533 continues.
SUMMARY...The threat for damaging winds and a tornado or two
persists across the watch area, and generally will decrease with
time and eastward extent.
DISCUSSION...Storms have largely transitioned to a more linear storm
mode as opposed to isolated supercells, most notably over southeast
MO where an earlier cluster outbreak of tornadoes occurred. Various
storms appear to contain damaging wind potential, with a few severe
gusts measured recently. Shear remains strong across the area ahead
of the cold front which now extends from western IL into southeast
MO.
Surface observations show relatively drier trajectories across TN
and KY, with 50s dewpoints into IN and parts of southeastern IL. As
such, the greatest severe threat in the short term will remain from
central IL into southeast MO where dewpoints remain in the 60s F
with MLCAPE around 1000 J/kg. Transient supercells remain possible,
either in isolated or embedded within the lines.
..Jewell.. 10/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PAH...ILX...LSX...SGF...
LAT...LON 39628781 38958806 37998834 37638849 37258894 36818955
36569036 36559173 36799179 37369106 38119028 38698987
39438972 40278996 40488955 40458903 40268820 40088785
39888769 39628781SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 24, 8:17 PM CDT | Mesoscale Discussion | SPC | Clinton, Franklin, Jackson, Jefferson, Marion, Monroe and 5 more | 118 min |
| Oct 24, 10:34 PM CDT | Tornado Watch | SPC | Dunklin, Pemiscot | 4 hr |
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.