Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 552
The Storm Prediction Center issued this mesoscale discussion at May 6, 2021, 1:10 PM CDT for 16 counties in Illinois. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 6, 2021, 1:10 PM CDT (18:10 UTC)
- Expired
- May 6, 2021, 3:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Champaign County, IL, Christian County, IL, Coles County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Effingham County, IL, Ford County, IL, Iroquois County, IL, Macon County, IL, Montgomery County, IL, Moultrie County, IL, Piatt County, IL, Shelby County, IL, Vermilion County, IL
The radar
The Lincoln radar (KILX), 73 km from the middle of the area, began a volume at 18:10 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, 6.2 hours before the alert went out and 19 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
- 16 J/kg
- Mixed-layer CIN
- -111 J/kg
- Mixed-layer LCL
- 1453 m above ground
- 0-6 km bulk shear
- 34 kt
- 0-1 km storm-relative helicity
- 203 m²/s²
- 0-3 km storm-relative helicity
- 211 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
420
ACUS11 KWNS 061810
SWOMCD
SPC MCD 061810
INZ000-ILZ000-062015-
Mesoscale Discussion 0552
NWS Storm Prediction Center Norman OK
0110 PM CDT Thu May 06 2021
Areas affected...Central/East-Central IL
Concerning...Severe potential...Watch unlikely
Valid 061810Z - 062015Z
Probability of Watch Issuance...5 percent
SUMMARY...Unique environment capable of brief landspouts will exist
across the region for the next few hours.
DISCUSSION...Filtered diurnal heating ahead of the front has
resulted in steep low-level lapse rates in a narrow corridor ahead
of the cold front across central/east-central IL. Steep mid-level
lapse rates exist atop these steep low-level lapse rates, resulting
in a thermodynamic profile characterized by at least 7.0 deg C/km
lapse rates from the surface to above 500-mb. Additionally,
increased surface vorticity exists in the immediate vicinity of the
frontal boundary.
Combination of the steep low-level lapse rates and surface vorticity
results in the unique environment where developing/deepening
updrafts could produce in brief landspouts. Limited and brief nature
of this threat precludes watch issuance.
..Mosier/Grams.. 05/06/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...IND...LOT...ILX...LSX...
LAT...LON 40308904 40788830 40758745 39608765 39018842 39218960
40308904SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 6, 9:52 AM CDT | Mesoscale Discussion | SPC | Bond, Calhoun, Clinton, Greene, Jersey, Macoupin and 7 more | 83 min |
| May 6, 10:05 AM CDT | Mesoscale Discussion | SPC | Alexander, Franklin, Gallatin, Hamilton, Hardin, Jackson and 10 more | 85 min |
| May 6, 12:02 PM CDT | Mesoscale Discussion | SPC | Alexander, Hardin, Jackson, Johnson, Massac, Pope and 4 more | 118 min |
| May 6, 12:38 PM CDT | Severe Thunderstorm Watch | SPC | Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more | 5 hr |
Nearby
Mesoscale Discussions in Illinois, 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.