Alert archive / Tennessee / Mesoscale Discussions in 2013

Mesoscale Discussion 746

May 21, 20135 states

The Storm Prediction Center issued this mesoscale discussion at May 21, 2013, 7:47 AM CDT for 5 states. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: May 21, 2013, 7:47 AM CDT (12:47 UTC)
Expired: May 21, 2013, 8:45 AM CDT
In force: 58 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 44 counties

Crittenden County, AR, Cross County, AR, Lee County, AR, Mississippi County, AR, Phillips County, AR, Poinsett County, AR, St. Francis County, AR, Fulton County, KY, Dunklin County, MO, Pemiscot County, MO, Alcorn County, MS, Benton County, MS, DeSoto County, MS, Lafayette County, MS, Marshall County, MS, Panola County, MS, Prentiss County, MS, Quitman County, MS, Tate County, MS, Tippah County, MS, Tunica County, MS, Union County, MS, Benton County, TN, Carroll County, TN, Chester County, TN, Crockett County, TN, Decatur County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Henry County, TN, Lake County, TN, Lauderdale County, TN, Madison County, TN, McNairy County, TN, Obion County, TN, Perry County, TN, Shelby County, TN, Tipton County, TN, Weakley County, TN

The radar

The Memphis radar (KNQA), 53 km from the middle of the area, began a volume at 12:47 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 (KLZK), launched 12:00Z, 0.8 hours before the alert went out and 98 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: 35 J/kg
Mixed-layer CIN: -268 J/kg
Mixed-layer LCL: 1441 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 17 m²/s²
0-3 km storm-relative helicity: 106 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 20, 7:39 PM CDT	Tornado Watch	SPC	Baxter, Benton, Boone, Carroll, Cleburne, Conway and 26 more	6 hr
May 21, 12:03 AM CDT	Severe Thunderstorm Watch	SPC	Crawford, Franklin, Sebastian	7 hr
May 21, 12:50 AM CDT	Severe Thunderstorm Watch	SPC	Clay, Craighead, Crittenden, Cross, Greene, Lawrence and 5 more	3 hr
May 21, 4:20 AM CDT	Mesoscale Discussion	SPC	Crawford, Franklin, Sebastian	55 min
May 21, 1:35 PM CDT	Mesoscale Discussion	SPC	Lafayette, Miller	115 min
May 21, 1:50 PM CDT	Tornado Watch	SPC	Bradley, Calhoun, Clark, Cleveland, Columbia, Dallas and 13 more	8 hr
May 21, 2:42 PM CDT	Mesoscale Discussion	SPC	Clay, Craighead, Crittenden, Cross, Greene, Jackson and 8 more	63 min
May 21, 3:00 PM CDT	Tornado Watch	SPC	Arkansas, Ashley, Chicot, Clay, Craighead, Crittenden and 11 more	7 hr
May 21, 3:18 PM CDT	Mesoscale Discussion	SPC	Bradley, Calhoun, Clark, Cleveland, Columbia, Dallas and 11 more	87 min
May 21, 5:54 PM CDT	Mesoscale Discussion	SPC	Calhoun, Columbia, Hempstead, Lafayette, Miller, Nevada and 2 more	66 min
May 21, 6:23 PM CDT	Mesoscale Discussion	SPC	Chicot, Desha	67 min
May 20, 10:25 PM CDT	Mesoscale Discussion	SPC	Ballard, Carlisle, Fulton, Graves, Hickman, Livingston and 2 more	65 min
May 20, 10:56 PM CDT	Tornado Watch	SPC	Ballard, Caldwell, Calloway, Carlisle, Crittenden, Fulton and 9 more	6 hr
May 21, 2:59 AM CDT	Mesoscale Discussion	SPC	Ballard, Caldwell, Calloway, Carlisle, Crittenden, Graves and 8 more	91 min
May 21, 11:27 AM CDT	Mesoscale Discussion	SPC	Adair, Allen, Barren, Clinton, Cumberland, Logan and 7 more	63 min
May 21, 2:12 PM CDT	Mesoscale Discussion	SPC	Adair, Anderson, Bell, Boyle, Breathitt, Casey and 36 more	63 min
May 21, 2:26 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Anderson, Bath, Bell, Bourbon, Boyd and 55 more	7 hr
May 21, 6:00 PM CDT	Mesoscale Discussion	SPC	Bath, Bell, Boyd, Breathitt, Carter, Clay and 22 more	60 min
May 20, 8:07 PM CDT	Mesoscale Discussion	SPC	Audrain, Callaway, Christian, Cole, Douglas, Gasconade and 15 more	23 min
May 20, 8:53 PM CDT	Mesoscale Discussion	SPC	Audrain, Franklin, Gasconade, Jefferson, Lewis, Lincoln and 10 more	67 min

Nearby

Mesoscale Discussions in Tennessee, 2013 Mesoscale Discussions in Mississippi, 2013 Mesoscale Discussions in Arkansas, 2013 Every mesoscale discussion in 2013

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.