Alert archive / Arkansas / Mesoscale Discussions in 2018

Mesoscale Discussion 238

April 13, 20184 states

The Storm Prediction Center issued this mesoscale discussion at Apr 13, 2018, 12:41 PM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 13, 2018, 12:41 PM CDT (17:41 UTC)
Expired: Apr 13, 2018, 2:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 95%

All 48 counties

Bradley County, AR, Calhoun County, AR, Clark County, AR, Cleveland County, AR, Columbia County, AR, Conway County, AR, Dallas County, AR, Faulkner County, AR, Garland County, AR, Grant County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Jefferson County, AR, Lafayette County, AR, Little River County, AR, Lonoke County, AR, Miller County, AR, Montgomery County, AR, Nevada County, AR, Ouachita County, AR, Perry County, AR, Pike County, AR, Polk County, AR, Pulaski County, AR, Saline County, AR, Sevier County, AR, Union County, AR, White County, AR, Yell County, AR, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, Webster Parish, LA, McCurtain County, OK, Bowie County, TX, Camp County, TX, Cass County, TX, Franklin County, TX, Gregg County, TX, Harrison County, TX, Marion County, TX, Morris County, TX, Panola County, TX, Red River County, TX, Rusk County, TX, Titus County, TX, Upshur County, TX

The radar

The Shreveport radar (KSHV), 150 km from the middle of the area, began a volume at 17:41 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.

The nearest sounding before it

Shreveport, LA (KBAD), launched 12:00Z, 5.7 hours before the alert went out and 147 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: 81 J/kg
Mixed-layer CIN: -535 J/kg
Mixed-layer LCL: 655 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 239 m²/s²
0-3 km storm-relative helicity: 283 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 13, 12:39 PM CDT	Mesoscale Discussion	SPC	Benton	2 hr
Apr 13, 1:20 PM CDT	Tornado Watch	SPC	Benton, Carroll, Crawford, Franklin, Madison, Sebastian and 1 more	9 hr
Apr 13, 1:50 PM CDT	Tornado Watch PDS	SPC	Baxter, Boone, Bradley, Calhoun, Clark, Cleburne and 43 more	8 hr
Apr 13, 3:43 PM CDT	Mesoscale Discussion	SPC	Benton, Washington	92 min
Apr 13, 5:53 PM CDT	Mesoscale Discussion	SPC	Arkansas, Ashley, Baxter, Boone, Bradley, Calhoun and 63 more	97 min
Apr 13, 6:50 PM CDT	Mesoscale Discussion	SPC	Ashley, Bradley, Chicot, Desha, Drew	115 min
Apr 13, 11:04 AM CDT	Mesoscale Discussion	SPC	Atoka, Bryan, Choctaw, Coal, Hughes, Johnston and 5 more	56 min
Apr 13, 4:49 PM CDT	Mesoscale Discussion	SPC	Bastrop, Bell, Blanco, Brazos, Burleson, Burnet and 14 more	2 hr

Nearby

Mesoscale Discussions in Arkansas, 2018 Mesoscale Discussions in Texas, 2018 Mesoscale Discussions in Louisiana, 2018 Every mesoscale discussion in 2018

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.