Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1121
The Storm Prediction Center issued this mesoscale discussion at Jun 28, 2021, 12:08 PM CDT for 4 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 28, 2021, 12:08 PM CDT (17:08 UTC)
- Expired
- Jun 28, 2021, 2:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 59 counties
Brown County, IL, Cass County, IL, Christian County, IL, DeWitt County, IL, Ford County, IL, Fulton County, IL, Greene County, IL, Grundy County, IL, Iroquois County, IL, Kankakee County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Marshall County, IL, Mason County, IL, McLean County, IL, Menard County, IL, Morgan County, IL, Peoria County, IL, Pike County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Tazewell County, IL, Will County, IL, Woodford County, IL, Benton County, IN, DeKalb County, IN, Elkhart County, IN, Fulton County, IN, Jasper County, IN, Kosciusko County, IN, LaGrange County, IN, Lake County, IN, LaPorte County, IN, Marshall County, IN, Newton County, IN, Noble County, IN, Porter County, IN, Pulaski County, IN, Saint Joseph County, IN, Starke County, IN, Steuben County, IN, White County, IN, Whitley County, IN, Berrien County, MI, Branch County, MI, Calhoun County, MI, Cass County, MI, Hillsdale County, MI, Ingham County, MI, Jackson County, MI, Kalamazoo County, MI, Lenawee County, MI, Saint Joseph County, MI, Washtenaw County, MI, Fulton County, OH, Williams County, OH
The radar
The Chicago radar (KLOT), 87 km from the middle of the area, began a volume at 17:10 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, 5.1 hours before the alert went out and 106 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
- 386 J/kg
- Mixed-layer CIN
- -70 J/kg
- Mixed-layer LCL
- 948 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km storm-relative helicity
- 38 m²/s²
- 0-3 km storm-relative helicity
- 59 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted.
568
ACUS11 KWNS 281709
SWOMCD
SPC MCD 281708
MIZ000-OHZ000-INZ000-ILZ000-281915-
Mesoscale Discussion 1121
NWS Storm Prediction Center Norman OK
1208 PM CDT Mon Jun 28 2021
Areas affected...Central Illinois...northern Indian...and southern
Michigan
Concerning...Severe potential...Watch unlikely
Valid 281708Z - 281915Z
Probability of Watch Issuance...5 percent
SUMMARY...Isolated to scattered thunderstorms will continue to
develop through the early to mid afternoon hours. Storms may be
capable of sporadic wind damage, but the overall severe threat will
generally remain low and a watch is not expected.
DISCUSSION...Recent radar and GOES IR imagery have shown a gradual
intensification in convection across central/southern IL and eastern
MO over the past hour. This is mostly attributable to diurnal
destabilization as temperatures warm into the mid to upper 80s amid
the moist, conditionally unstable thermodynamic profiles observed
across the Midwest in morning soundings. Mesoanalysis estimates
suggest MLCAPE values near 1000-1500 J/kg are already in place, and
further destabilization is likely through the mid afternoon via
continued daytime heating. The mid/upper-level jet is largely
displaced to the north of the warmer, more unstable air mass, but a
narrow overlap of 30-35 knots of effective bulk shear exists within
the IL to MI corridor that may support some storm organization.
Initially discrete cells developing along a weak frontal zone will
likely evolve into clusters through the afternoon and may be capable
of sporadic wind damage. Overall the severe threat is expected to be
limited given marginal lapse rates and the narrow overlap of
adequate CAPE/shear, and a watch is not expected.
..Moore/Thompson.. 06/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CLE...DTX...IWX...GRR...IND...LOT...ILX...LSX...
DVN...
LAT...LON 40409060 40948967 41588756 42028639 42308539 42708443
42328337 41658357 41238489 40628692 40068856 39048979
39119052 39459087 39949107 40409060Nearby
Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Indiana, 2021Mesoscale Discussions in Michigan, 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.