Alert archive / Illinois / Mesoscale Discussions in 2017

Mesoscale Discussion 561

April 26, 201722 counties in Illinois; Ballard County, Kentucky; 12 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Apr 26, 2017, 12:26 PM CDT for 22 counties in Illinois; Ballard County, Kentucky; 12 counties in Missouri. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: Apr 26, 2017, 12:26 PM CDT (17:26 UTC)
Expired: Apr 26, 2017, 2:00 PM CDT
In force: 94 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 35 counties

Alexander County, IL, Clay County, IL, Clinton County, IL, Edwards County, IL, Franklin County, IL, Hamilton County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Johnson County, IL, Lawrence County, IL, Marion County, IL, Perry County, IL, Pulaski County, IL, Randolph County, IL, Richland County, IL, Saline County, IL, Union County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Ballard County, KY, Bollinger County, MO, Butler County, MO, Cape Girardeau County, MO, Carter County, MO, Madison County, MO, Mississippi County, MO, Perry County, MO, Ripley County, MO, Sainte Genevieve County, MO, Scott County, MO, Stoddard County, MO, Wayne County, MO

The radar

The Paducah radar (KPAH), 66 km from the middle of the area, began a volume at 17:28 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.

Severe Thunderstorm Watch 163Apr 26, 12:45 PM CDT

The nearest sounding before it

Nashville Metro, TN (KBNA), launched 12:00Z, 5.4 hours before the alert went out and 282 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1165 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 138 m²/s²
0-3 km storm-relative helicity: 114 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
Apr 26, 12:46 PM CDT	Severe Thunderstorm Watch	SPC	Alexander, Bond, Clark, Clay, Clinton, Crawford and 19 more	6 hr
Apr 26, 3:53 PM CDT	Mesoscale Discussion	SPC	Alexander, Clark, Clay, Coles, Crawford, Cumberland and 16 more	97 min
Apr 26, 6:10 PM CDT	Mesoscale Discussion	SPC	Hardin, Massac, Pope	95 min
Apr 25, 7:14 PM CDT	Mesoscale Discussion	SPC	McDonald	91 min
Apr 25, 10:51 PM CDT	Mesoscale Discussion	SPC	Barry, Barton, Bates, Benton, Camden, Cedar and 18 more	54 min
Apr 25, 11:27 PM CDT	Severe Thunderstorm Watch	SPC	Barry, Christian, Dade, Douglas, Greene, Howell and 5 more	7 hr
Apr 26, 1:42 AM CDT	Mesoscale Discussion	SPC	Barry, Christian, Douglas, Greene, Ozark, Stone and 3 more	2 hr
Apr 26, 9:39 AM CDT	Mesoscale Discussion	SPC	Butler, Carter, Dunklin, Howell, New Madrid, Oregon and 3 more	36 min
Apr 26, 5:02 PM CDT	Severe Thunderstorm Watch	SPC	Dunklin, Pemiscot	6 hr

Nearby

Mesoscale Discussions in Illinois, 2017 Mesoscale Discussions in Missouri, 2017 Mesoscale Discussions in Kentucky, 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.