Alert archive / Illinois / Mesoscale Discussions in 2018

Mesoscale Discussion 810

June 21, 20188 counties in Illinois; 5 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at Jun 21, 2018, 1:53 PM CDT for 8 counties in Illinois; 5 counties in Iowa. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jun 21, 2018, 1:53 PM CDT (18:53 UTC)
Expired: Jun 21, 2018, 4:30 PM CDT
In force: 3 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Benton County, IA, Cedar County, IA, Linn County, IA, Muscatine County, IA, Scott County, IA, Henry County, IL, Knox County, IL, Marshall County, IL, Peoria County, IL, Rock Island County, IL, Stark County, IL, Tazewell County, IL, Woodford County, IL

The radar

The Quad Cities radar (KDVN), 44 km from the middle of the area, began a volume at 18:54 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 12:00Z, 6.9 hours before the alert went out and 42 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: 263 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 469 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 25 m²/s²
0-3 km storm-relative helicity: 40 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
Jun 21, 12:31 PM CDT	Mesoscale Discussion	SPC	Alexander, Franklin, Gallatin, Hardin, Jackson, Johnson and 6 more	2 hr
Jun 21, 1:39 PM CDT	Severe Thunderstorm Watch	SPC	Alexander, Hardin, Johnson, Massac, Pope, Pulaski and 1 more	7 hr
Jun 21, 3:56 PM CDT	Mesoscale Discussion	SPC	Alexander, Hardin, Johnson, Massac, Pope, Pulaski and 1 more	2 hr
Jun 21, 5:44 PM CDT	Mesoscale Discussion	SPC	Massac	2 hr

Nearby

Mesoscale Discussions in Illinois, 2018 Mesoscale Discussions in Iowa, 2018 Every mesoscale discussion in 2018

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.