Alert archive / Illinois / Mesoscale Discussions in 2021

Mesoscale Discussion 1997

December 10, 20216 counties in Illinois; Vigo County, Indiana

The Storm Prediction Center issued this mesoscale discussion at Dec 10, 2021, 9:36 PM CST for 6 counties in Illinois; Vigo County, Indiana. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued: Dec 10, 2021, 9:36 PM CST (03:36 UTC)
Expired: Dec 10, 2021, 10:30 PM CST
In force: 54 min
Issued by: the Storm Prediction Center
Concerning: Tornado watch 557

Counties Clark County, IL, Coles County, IL, Cumberland County, IL, Edgar County, IL, Effingham County, IL, Shelby County, IL, Vigo County, IN

The radar

The Evansville,IN radar (KVWX), 122 km from the middle of the area, began a volume at 03:38 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, 3.6 hours before the alert went out and 101 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 119 J/kg
Mixed-layer CIN: -33 J/kg
Mixed-layer LCL: 662 m above ground
0-6 km bulk shear: 73 kt
0-1 km storm-relative helicity: 341 m²/s²
0-3 km storm-relative helicity: 357 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

996 
ACUS11 KWNS 110337
SWOMCD
SPC MCD 110336 
INZ000-ILZ000-110430-

Mesoscale Discussion 1997
NWS Storm Prediction Center Norman OK
0936 PM CST Fri Dec 10 2021

Areas affected...portions of central Illinois

Concerning...Tornado Watch 557...

Valid 110336Z - 110430Z

The severe weather threat for Tornado Watch 557 continues.

SUMMARY...A strong tornado threat is expected to persist for the
next 1 to 2 hours across central and east-central Illinois.

DISCUSSION...The supercell on the southern edge of a line of storms
moving across central Illinois has produced several tornado debris
signatures so far. This portion of the line will remain the favored
location for tornadoes given the lack of storm interference, low to
mid 60s dewpoints, and very strong low-level shear (0-1 km SRH in
excess of 600 m2/s2 per both ILX and VWX VWP). In addition, this
environment will support the potential for strong tornadoes,
especially as the storm inflow remains uninhibited.

..Bentley.. 12/11/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...IND...ILX...LSX...

LAT...LON   38998882 39058900 39278918 39618877 39768734 39538700
            39198730 39048834 38998882

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 10, 7:02 PM CST	Mesoscale Discussion	SPC	Calhoun, Greene, Jersey, Macoupin, Madison, Monroe and 4 more	58 min
Dec 10, 7:18 PM CST	Mesoscale Discussion	SPC	Champaign, Christian, Clark, Clay, Coles, Crawford and 18 more	87 min
Dec 10, 7:47 PM CST	Tornado Watch	SPC	Champaign, Clark, Clay, Coles, Crawford, Cumberland and 21 more	8 hr
Dec 10, 8:53 PM CST	Mesoscale Discussion	SPC	Bond, Champaign, Christian, Clark, Clay, Coles and 21 more	97 min
Dec 10, 10:09 PM CST	Mesoscale Discussion	SPC	Massac	96 min
Dec 10, 11:03 PM CST	Tornado Watch	SPC	Alexander, Clinton, Edwards, Fayette, Franklin, Gallatin and 17 more	5 hr
Dec 10, 11:28 PM CST	Mesoscale Discussion	SPC	Alexander, Clark, Clay, Coles, Crawford, Cumberland and 24 more	92 min
Dec 10, 6:21 PM CST	Tornado Watch	SPC	Clark, Crawford, Dubois, Floyd, Harrison, Jefferson and 4 more	10 hr
Dec 10, 8:35 PM CST	Mesoscale Discussion	SPC	Harrison	85 min
Dec 10, 10:25 PM CST	Mesoscale Discussion	SPC	Bartholomew, Benton, Blackford, Boone, Brown, Carroll and 50 more	95 min
Dec 10, 11:08 PM CST	Mesoscale Discussion	SPC	Dearborn, Decatur, Delaware, Fayette, Franklin, Hamilton and 16 more	67 min
Dec 10, 11:20 PM CST	Tornado Watch	SPC	Adams, Allen, Blackford, Carroll, Cass, Dearborn and 27 more	6 hr
Dec 11, 1:46 AM CST	Mesoscale Discussion	SPC	Bartholomew, Brown, Daviess, Dearborn, Decatur, Delaware and 21 more	59 min

Nearby

Mesoscale Discussions in Illinois, 2021 Mesoscale Discussions in Indiana, 2021 Every 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.