Alert archive / Indiana / Mesoscale Discussions in 2017

Mesoscale Discussion 1375

July 21, 201713 counties in Illinois; 16 counties in Indiana

The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2017, 1:11 AM CDT for 13 counties in Illinois; 16 counties in Indiana. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: Jul 21, 2017, 1:11 AM CDT (06:11 UTC)
Expired: Jul 21, 2017, 2:45 AM CDT
In force: 94 min
Issued by: the Storm Prediction Center
Chance of a watch: 5%

All 29 counties

Bureau County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Kankakee County, IL, LaSalle County, IL, Livingston County, IL, Marshall County, IL, Peoria County, IL, Putnam County, IL, Stark County, IL, Will County, IL, Woodford County, IL, Benton County, IN, Carroll County, IN, Cass County, IN, Clinton County, IN, Fulton County, IN, Howard County, IN, Jasper County, IN, Miami County, IN, Newton County, IN, Pulaski County, IN, Starke County, IN, Tippecanoe County, IN, Tipton County, IN, Wabash County, IN, Warren County, IN, White County, IN

The radar

The Chicago radar (KLOT), 84 km from the middle of the area, began a volume at 06:15 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

Davenport, (KDVN), launched 00:00Z, 6.2 hours before the alert went out and 233 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: 2392 J/kg
Mixed-layer CIN: -69 J/kg
Mixed-layer LCL: 1284 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 56 m²/s²
0-3 km storm-relative helicity: 151 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 7.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 21, 1:32 PM CDT	Mesoscale Discussion	SPC	Carroll, Henry, Jo Daviess, Lee, Mercer, Ogle and 2 more	2 hr
Jul 21, 4:52 PM CDT	Severe Thunderstorm Watch	SPC	Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 28 more	9 hr
Jul 21, 6:28 PM CDT	Mesoscale Discussion	SPC	Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 23 more	92 min

Nearby

Mesoscale Discussions in Indiana, 2017 Mesoscale Discussions in Illinois, 2017 Every mesoscale discussion in 2017

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.