Alert archive / Arkansas / Mesoscale Discussions in 2013

Mesoscale Discussion 522

April 18, 20138 states

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2013, 12:48 PM CDT for 8 states. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued: Apr 18, 2013, 12:48 PM CDT (17:48 UTC)
Expired: Apr 18, 2013, 2:15 PM CDT
In force: 87 min
Issued by: the Storm Prediction Center

All 136 counties

Arkansas County, AR, Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Clay County, AR, Cleveland County, AR, Columbia County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Grant County, AR, Greene County, AR, Independence County, AR, Jackson County, AR, Jefferson County, AR, Lawrence County, AR, Lee County, AR, Lincoln County, AR, Lonoke County, AR, Mississippi County, AR, Monroe County, AR, Ouachita County, AR, Phillips County, AR, Poinsett County, AR, Prairie County, AR, Pulaski County, AR, Randolph County, AR, St. Francis County, AR, Union County, AR, White County, AR, Woodruff County, AR, Alexander County, IL, Edwards County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Jackson County, IL, Jefferson County, IL, Johnson County, IL, Massac County, IL, Perry County, IL, Pope County, IL, Pulaski County, IL, Saline County, IL, Union County, IL, Wabash County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Dubois County, IN, Gibson County, IN, Pike County, IN, Posey County, IN, Spencer County, IN, Vanderburgh County, IN, Warrick County, IN, Ballard County, KY, Caldwell County, KY, Calloway County, KY, Carlisle County, KY, Crittenden County, KY, Fulton County, KY, Graves County, KY, Henderson County, KY, Hickman County, KY, Hopkins County, KY, Livingston County, KY, Lyon County, KY, Marshall County, KY, McCracken County, KY, McLean County, KY, Trigg County, KY, Union County, KY, Webster County, KY, Bienville Parish, LA, Claiborne Parish, LA, East Carroll Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Richland Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Bollinger County, MO, Butler County, MO, Cape Girardeau County, MO, Dunklin County, MO, Mississippi County, MO, New Madrid County, MO, Pemiscot County, MO, Perry County, MO, Ripley County, MO, Scott County, MO, Stoddard County, MO, Wayne County, MO, Benton County, MS, Bolivar County, MS, Coahoma County, MS, DeSoto County, MS, Grenada County, MS, Humphreys County, MS, Issaquena County, MS, Lafayette County, MS, Leflore County, MS, Marshall County, MS, Panola County, MS, Quitman County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Tate County, MS, Tunica County, MS, Washington County, MS, Yalobusha County, MS, Carroll County, TN, Crockett County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Haywood County, TN, Henry County, TN, Lake County, TN, Lauderdale County, TN, Madison County, TN, Obion County, TN, Shelby County, TN, Tipton County, TN, Weakley County, TN

The radar

The Memphis radar (KNQA), 52 km from the middle of the area, began a volume at 17:48 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 126Apr 18, 1:45 PM CDT

The nearest sounding before it

Little Rock, AR (KLZK), launched 12:00Z, 5.8 hours before the alert went out and 63 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: 1219 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 578 m above ground
0-6 km bulk shear: 49 kt
0-1 km storm-relative helicity: 421 m²/s²
0-3 km storm-relative helicity: 522 m²/s²
Significant tornado parameter: 3.3
Supercell composite: 19.6

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
Apr 17, 10:47 PM CDT	Tornado Watch	SPC	Benton, Carroll, Crawford, Madison, Washington	7 hr
Apr 18, 2:01 AM CDT	Mesoscale Discussion	SPC	Benton, Boone, Carroll, Crawford, Franklin, Madison and 2 more	89 min
Apr 18, 4:02 AM CDT	Mesoscale Discussion	SPC	Baxter, Boone, Carroll, Conway, Crawford, Franklin and 17 more	58 min
Apr 18, 7:26 AM CDT	Mesoscale Discussion	SPC	Baxter, Boone, Clay, Cleburne, Conway, Craighead and 20 more	2 hr
Apr 18, 9:25 AM CDT	Tornado Watch	SPC	Arkansas, Baxter, Bradley, Calhoun, Clark, Clay and 43 more	8 hr
Apr 18, 1:43 PM CDT	Tornado Watch	SPC	Ashley, Chicot, Union	8 hr
Apr 17, 8:21 PM CDT	Mesoscale Discussion	SPC	Cass, Champaign, Christian, Coles, DeWitt, Douglas and 21 more	84 min
Apr 17, 8:53 PM CDT	Mesoscale Discussion	SPC	Calhoun, Greene, Jersey, Pike, Scott	97 min
Apr 17, 9:57 PM CDT	Tornado Watch	SPC	Adams, Brown, Pike	7 hr
Apr 17, 10:48 PM CDT	Mesoscale Discussion	SPC	Champaign, Christian, Coles, DeWitt, Douglas, Edgar and 12 more	57 min
Apr 17, 11:46 PM CDT	Mesoscale Discussion	SPC	Calhoun, Greene, Morgan, Pike, Scott	89 min
Apr 18, 5:36 AM CDT	Mesoscale Discussion	SPC	Bond, Clinton, Fayette, Madison, Monroe, Montgomery and 3 more	54 min
Apr 18, 5:42 AM CDT	Tornado Watch	SPC	Bond, Clinton, Fayette, Jersey, Macoupin, Madison and 6 more	8 hr
Apr 18, 7:25 AM CDT	Mesoscale Discussion	SPC	Champaign, Clark, Clay, Coles, Crawford, Cumberland and 17 more	95 min
Apr 18, 8:31 AM CDT	Tornado Watch PDS	SPC	Clark, Clay, Coles, Crawford, Cumberland, Douglas and 6 more	7 hr
Apr 18, 11:14 AM CDT	Mesoscale Discussion	SPC	Clark, Clay, Crawford, Jasper, Lawrence, Marion and 4 more	2 hr
Apr 18, 2:47 PM CDT	Mesoscale Discussion	SPC	Clark, Crawford, Lawrence	88 min
Apr 18, 3:32 PM CDT	Tornado Watch	SPC	Adams, Bartholomew, Blackford, Boone, Brown, Clay and 27 more	3 hr
Apr 18, 5:33 PM CDT	Mesoscale Discussion	SPC	Adams, Allen, Bartholomew, Blackford, Boone, Brown and 43 more	117 min
Apr 18, 4:56 PM CDT	Mesoscale Discussion	SPC	East Carroll, Franklin, Madison, Tensas, West Carroll	94 min
Apr 18, 5:52 PM CDT	Tornado Watch	SPC	Calhoun, Chickasaw, Itawamba, Lafayette, Lee, Monroe and 6 more	5 hr
Apr 18, 6:52 PM CDT	Mesoscale Discussion	SPC	Attala, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 12 more	83 min

Nearby

Mesoscale Discussions in Arkansas, 2013 Mesoscale Discussions in Illinois, 2013 Mesoscale Discussions in Mississippi, 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.