Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1602
The Storm Prediction Center issued this mesoscale discussion at Aug 25, 2021, 4:02 PM CDT for 34 counties in Illinois; Vermillion County, Warren County, Indiana. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Aug 25, 2021, 4:02 PM CDT (21:02 UTC)
- Expired
- Aug 25, 2021, 5:30 PM CDT
- In force
- 88 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 36 counties
Bureau County, IL, Champaign County, IL, Clark County, IL, Coles County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Ford County, IL, Fulton County, IL, Grundy County, IL, Henry County, IL, Iroquois County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Marshall County, IL, Mason County, IL, McLean County, IL, Menard County, IL, Mercer County, IL, Moultrie County, IL, Peoria County, IL, Piatt County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Tazewell County, IL, Vermilion County, IL, Warren County, IL, Whiteside County, IL, Woodford County, IL, Vermillion County, IN, Warren County, IN
The radar
The Lincoln radar (KILX), 58 km from the middle of the area, began a volume at 21:04 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, 9.0 hours before the alert went out and 73 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
- 1708 J/kg
- Mixed-layer CIN
- -135 J/kg
- Mixed-layer LCL
- 1029 m above ground
- 0-6 km bulk shear
- 9 kt
- 0-1 km storm-relative helicity
- 132 m²/s²
- 0-3 km storm-relative helicity
- 170 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 4.9
The text
As transmitted.
679
ACUS11 KWNS 252103
SWOMCD
SPC MCD 252102
INZ000-ILZ000-IAZ000-252230-
Mesoscale Discussion 1602
NWS Storm Prediction Center Norman OK
0402 PM CDT Wed Aug 25 2021
Areas affected...Illinois and western Indiana
Concerning...Severe potential...Watch unlikely
Valid 252102Z - 252230Z
Probability of Watch Issuance...5 percent
SUMMARY...Isolated to scattered storm development is possible this
afternoon/evening with a risk for a few damaging wind gusts or hail.
Given the limited coverage, a weather watch is not expected.
DISCUSSION...Within a weakly forced and sheared environment ahead of
a weak MCV over eastern Iowa, gradual destabilization has resulted
in a few storms across far western Illinois and Indiana. Satellite
trends and hi-res guidance suggest additional storm development with
a risk for strong winds or hail is probable over the next few hours.
SPC mesoanalysis indicates 2000-3000 J/kg of MLCAPE is present
across much of Illinois owing to strong heating and surface
dewpoints in the 70s F. As the cluster of storms east of Davenport
continues south and east, strong buoyancy will continue to support
vigorous updrafts with occasional hail or damaging gust potential.
CAM guidance is not overly bullish with any organization of the
ongoing convection. However, hints at a weak cold pool developing
suggest some clustering may occur as storms move southeastward.
Across far western Indiana and eastern Illinois, a westward
propagating cluster of storms may also pose an isolated risk for
downbursts this evening. Little vertical shear is in place with
multicell storms exhibiting pulse characteristics. However, as
additional development takes place, collapsing storms may produce a
few strong wind gusts into this evening.
..Lyons/Kerr.. 08/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...IND...LOT...ILX...DVN...
LAT...LON 41909017 41848914 41298827 40858780 40568744 40208722
39688734 39308774 39378845 39548908 39858980 40249031
40629062 40959085 41399073 41689055 41909017SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 24, 8:14 PM CDT | Mesoscale Discussion | SPC | Grundy, Kankakee, Knox, Livingston, Marshall, Peoria and 2 more | 2 hr |
| Aug 25, 11:46 AM CDT | Mesoscale Discussion | SPC | Bartholomew, Boone, Brown, Clay, Dearborn, Decatur and 27 more | 2 hr |
Nearby
Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Indiana, 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.