Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1895
The Storm Prediction Center issued this mesoscale discussion at Oct 24, 2021, 8:17 PM CDT for 11 counties in Illinois; 10 counties in Missouri. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Oct 24, 2021, 8:17 PM CDT (01:17 UTC)
- Expired
- Oct 24, 2021, 10:15 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 533
All 21 counties
Clinton County, IL, Franklin County, IL, Jackson County, IL, Jefferson County, IL, Marion County, IL, Monroe County, IL, Perry County, IL, Randolph County, IL, Saint Clair County, IL, Union County, IL, Washington County, IL, Bollinger County, MO, Cape Girardeau County, MO, Carter County, MO, Iron County, MO, Madison County, MO, Perry County, MO, Reynolds County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Wayne County, MO
The radar
The Paducah radar (KPAH), 125 km from the middle of the area, began a volume at 01:19 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, 1.3 hours before the alert went out and 290 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.
314
ACUS11 KWNS 250117
SWOMCD
SPC MCD 250117
ILZ000-MOZ000-250315-
Mesoscale Discussion 1895
NWS Storm Prediction Center Norman OK
0817 PM CDT Sun Oct 24 2021
Areas affected...southeast Missouri into southern Illinois
Concerning...Tornado Watch 533...
Valid 250117Z - 250315Z
The severe weather threat for Tornado Watch 533 continues.
SUMMARY...The greatest tornado threat is currently over southeastern
Missouri, and is expected to shift into southern Illinois.
DISCUSSION...A trio of supercells currently extends from Ste.
Genevieve into Reynolds County MO, with strong mesocyclones noted on
radar. Storm mode appears complex with substantial precipitation
ahead of the circulations.
These storms are currently near the instability axis, with MLCAPE
around 1500 J/kg. Dewpoints rapidly decrease toward the Wabash/Lower
Ohio Valleys, but favorable instability should remain in place
toward the MS River and into parts of southern Illinois. Here, 0-1
SRH exceeds 300 m2/s2, which is quite favorable for tornadoes and
supercells producing damaging wind gusts.
..Jewell.. 10/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PAH...ILX...LSX...SGF...
LAT...LON 37028960 36829059 36949122 37239123 37709065 38149057
38519017 38808910 38698864 38398841 37688907 37028960SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 24, 10:33 PM CDT | Mesoscale Discussion | SPC | Alexander, Bond, Champaign, Christian, Clay, Clinton and 31 more | 2 hr |
| 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.