Alert archive / Missouri / Mesoscale Discussions in 2017

Mesoscale Discussion 797

May 20, 20175 states

The Storm Prediction Center issued this mesoscale discussion at May 20, 2017, 1:45 AM CDT for 5 states. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: May 20, 2017, 1:45 AM CDT (06:45 UTC)
Expired: May 20, 2017, 3:15 AM CDT
In force: 90 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 49 counties

Clay County, AR, Cleburne County, AR, Craighead County, AR, Fulton County, AR, Greene County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Lawrence County, AR, Poinsett County, AR, Randolph County, AR, Sharp County, AR, Stone County, AR, Alexander County, IL, Edwards County, IL, Franklin County, IL, Hamilton County, IL, Jackson County, IL, Jefferson County, IL, Johnson County, IL, Perry County, IL, Pulaski County, IL, Randolph 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, Dunklin County, MO, Iron County, MO, Madison County, MO, Mississippi County, MO, New Madrid County, MO, Oregon County, MO, Pemiscot County, MO, Perry County, MO, Reynolds County, MO, Ripley County, MO, Sainte Genevieve County, MO, Scott County, MO, Stoddard County, MO, Wayne County, MO, Lake County, TN

The radar

The Paducah radar (KPAH), 110 km from the middle of the area, began a volume at 06:46 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

Little Rock, AR (KBYH), launched 00:00Z, 6.8 hours before the alert went out and 250 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: 1585 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 1413 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 62 m²/s²
0-3 km storm-relative helicity: 108 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 4.3

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 19, 9:16 PM CDT	Mesoscale Discussion	SPC	Baxter, Benton, Boone, Carroll, Cleburne, Conway and 22 more	59 min
May 19, 9:42 PM CDT	Tornado Watch	SPC	Baxter, Benton, Boone, Carroll, Crawford, Franklin and 14 more	7 hr
May 19, 11:51 PM CDT	Mesoscale Discussion	SPC	Baxter, Boone, Carroll, Conway, Crawford, Franklin and 18 more	114 min
May 19, 9:18 PM CDT	Mesoscale Discussion	SPC	Breathitt, Clay, Floyd, Jackson, Johnson, Knott and 16 more	87 min
May 20, 11:13 AM CDT	Mesoscale Discussion	SPC	Boone, Breckinridge, Bullitt, Butler, Caldwell, Calloway and 35 more	92 min
May 20, 3:23 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Allen, Anderson, Barren, Bourbon, Boyle and 43 more	7 hr
May 20, 5:42 PM CDT	Mesoscale Discussion	SPC	Boone, Breckinridge, Bullitt, Butler, Caldwell, Calloway and 35 more	2 hr

Nearby

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