Alert archive / Illinois / Mesoscale Discussions in 2020

Mesoscale Discussion 685

May 23, 20204 states

The Storm Prediction Center issued this mesoscale discussion at May 23, 2020, 2:51 PM CDT for 4 states. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: May 23, 2020, 2:51 PM CDT (19:51 UTC)
Expired: May 23, 2020, 4:15 PM CDT
In force: 84 min
Issued by: the Storm Prediction Center
Concerning: Tornado watch 207

All 71 counties

Benton County, IA, Buchanan County, IA, Cedar County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Jackson County, IA, Johnson County, IA, Jones County, IA, Linn County, IA, Scott County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, Champaign County, IL, Cook County, IL, DeKalb County, IL, DeWitt County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Henry County, IL, Iroquois County, IL, Jo Daviess County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Logan County, IL, Marshall County, IL, Mason County, IL, McHenry County, IL, McLean County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Vermilion County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Woodford County, IL, Benton County, IN, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN, Warren County, IN, White County, IN, Crawford County, WI, Dane County, WI, Grant County, WI, Green County, WI, Iowa County, WI, Jefferson County, WI, Kenosha County, WI, Lafayette County, WI, Milwaukee County, WI, Racine County, WI, Rock County, WI, Walworth County, WI, Waukesha County, WI

The radar

The Quad Cities radar (KDVN), 71 km from the middle of the area, began a volume at 19:51 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 211May 23, 4:55 PM CDT

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 7.9 hours before the alert went out and 65 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: 145 J/kg
Mixed-layer CIN: -133 J/kg
Mixed-layer LCL: 859 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 148 m²/s²
0-3 km storm-relative helicity: 198 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

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
May 23, 11:29 AM CDT	Mesoscale Discussion	SPC	Bureau, Carroll, Cass, DeWitt, Fulton, Henderson and 24 more	2 hr
May 23, 12:33 PM CDT	Tornado Watch	SPC	Boone, Bureau, Carroll, Cook, DeKalb, DeWitt and 35 more	8 hr
May 23, 3:14 PM CDT	Mesoscale Discussion	SPC	Bartholomew, Brown, Dearborn, Decatur, Fayette, Franklin and 11 more	61 min
May 23, 4:57 PM CDT	Tornado Watch	SPC	Cass, Fulton, LaPorte, Marshall, Miami, Pulaski and 3 more	4 hr

Nearby

Mesoscale Discussions in Illinois, 2020 Mesoscale Discussions in Iowa, 2020 Mesoscale Discussions in Wisconsin, 2020 Every mesoscale discussion in 2020

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.