Alert archive / Illinois / Mesoscale Discussions in 2023
Mesoscale Discussion 721
The Storm Prediction Center issued this mesoscale discussion at May 7, 2023, 6:10 PM CDT for 14 counties in Illinois; Saint Louis County, City of Saint Louis, Missouri. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 7, 2023, 6:10 PM CDT (23:10 UTC)
- Expired
- May 7, 2023, 8:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 195
Counties Bond County, IL, Cass County, IL, Christian County, IL, Greene County, IL, Jersey County, IL, Macoupin County, IL, Madison County, IL, Mason County, IL, Menard County, IL, Montgomery County, IL, Morgan County, IL, Saint Clair County, IL, Sangamon County, IL, Scott County, IL, City of Saint Louis, MO, Saint Louis County, MO
The radar
The St Louis radar (KLSX), 99 km from the middle of the area, began a volume at 23:14 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, 11.2 hours before the alert went out and 141 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
- 668 J/kg
- Mixed-layer CIN
- -187 J/kg
- Mixed-layer LCL
- 887 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km storm-relative helicity
- 214 m²/s²
- 0-3 km storm-relative helicity
- 250 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 4.8
The text
As transmitted.
890
ACUS11 KWNS 072310
SWOMCD
SPC MCD 072310
ILZ000-MOZ000-080115-
Mesoscale Discussion 0721
NWS Storm Prediction Center Norman OK
0610 PM CDT Sun May 07 2023
Areas affected...southwest into central IL...Saint Louis MO vicinity
Concerning...Severe Thunderstorm Watch 195...
Valid 072310Z - 080115Z
The severe weather threat for Severe Thunderstorm Watch 195
continues.
SUMMARY...Isolated large hail will be favored with the stronger, new
intensifying updrafts with an unobstructed feed of lapse rates from
the west, through the early evening.
DISCUSSION...Visible satellite/radar mosaic composite shows a
cluster of storms over central IL southward to the eastern portion
of the Saint Louis metro. This activity has developed in response
to a westward-surging outflow boundary (oriented north to south)
moving through Saint Louis and into west-central IL. Surface
temperatures west of the boundary are very warm with temperatures
near 90 deg and dewpoints ranging from the mid-upper 50s to near 60
deg. A narrow corridor of moderate to strong buoyancy (2000-3000
J/kg MLCAPE) is currently analyzed near the outflow boundary. It
seems plausible a few additional stronger storms will be capable of
an isolated risk for large hail through the early evening. It
remains uncertain whether storms will develop west of the MS River
in the near term. However, west-central and central IL will
probably have a renewed risk for severe as ongoing severe
thunderstorm activity over eastern IA potentially moves into
northern parts of severe thunderstorm watch 195 between 8-9pm (9pm
is watch expiration time).
..Smith.. 05/07/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ILX...LSX...
LAT...LON 40389015 40308988 39388891 39228893 38978934 38738949
38358946 38228977 38269010 38639062 39969061 40209049
40389015SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 6, 8:12 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Cass, Christian, Fulton, Greene and 22 more | 93 min |
| May 6, 8:50 PM CDT | Severe Thunderstorm Watch | SPC | Fulton, Hancock, Henderson, Knox, McDonough, Mercer and 2 more | 7 hr |
| May 6, 9:00 PM CDT | Tornado Watch | SPC | Adams, Brown, Pike | 5 hr |
| May 6, 10:44 PM CDT | Severe Thunderstorm Watch | SPC | Cass, Champaign, Christian, Coles, Cumberland, DeWitt and 15 more | 6 hr |
| May 6, 11:34 PM CDT | Mesoscale Discussion | SPC | Brown, Cass, Fulton, Hancock, Henderson, Knox and 11 more | 86 min |
| May 7, 1:37 AM CDT | Mesoscale Discussion | SPC | Fulton, Hancock, Henderson, Knox, McDonough, Mason and 3 more | 113 min |
| May 7, 2:21 AM CDT | Mesoscale Discussion | SPC | Clark, Coles, Cumberland, Moultrie | 114 min |
| May 7, 4:05 AM CDT | Mesoscale Discussion | SPC | Christian, Clark, Coles, Crawford, Cumberland, Douglas and 7 more | 85 min |
| May 7, 1:00 PM CDT | Mesoscale Discussion | SPC | Alexander, Bond, Christian, Clay, Clinton, Effingham and 30 more | 2 hr |
| May 7, 1:18 PM CDT | Severe Thunderstorm Watch | SPC | Alexander, Bond, Calhoun, Cass, Christian, Clay and 47 more | 10 hr |
| May 7, 3:40 PM CDT | Mesoscale Discussion | SPC | Bond, Cass, Christian, Clay, Clinton, Edwards and 35 more | 65 min |
| May 7, 4:10 PM CDT | Severe Thunderstorm Watch | SPC | Bureau, Carroll, Hancock, Henderson, Henry, Jo Daviess and 10 more | 10 hr |
| May 7, 5:35 PM CDT | Mesoscale Discussion | SPC | Bureau, Carroll, Cass, Fulton, Hancock, Henderson and 11 more | 85 min |
| May 7, 6:40 PM CDT | Mesoscale Discussion | SPC | Ford, Grundy, Iroquois, Kankakee, Kendall, LaSalle and 2 more | 65 min |
| May 7, 6:58 PM CDT | Severe Thunderstorm Watch | SPC | Ford, Grundy, Iroquois, Kankakee, Kendall, LaSalle and 5 more | 5 hr |
| May 6, 11:24 PM CDT | Mesoscale Discussion | SPC | Marion, Ralls, Shelby | 96 min |
| May 7, 6:02 PM CDT | Mesoscale Discussion | SPC | Andrew, Atchison, Buchanan, Gentry, Holt, Nodaway and 1 more | 88 min |
| May 7, 6:45 PM CDT | Severe Thunderstorm Watch | SPC | Andrew, Atchison, Holt, Nodaway | 6 hr |
Nearby
Mesoscale Discussions in Illinois, 2023Mesoscale Discussions in Missouri, 2023Every mesoscale discussion in 2023
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.