Alert archive / Arkansas / Mesoscale Discussions in 2013

Mesoscale Discussion 20

January 12, 20134 states

The Storm Prediction Center issued this mesoscale discussion at Jan 12, 2013, 9:25 PM CST for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jan 12, 2013, 9:25 PM CST (03:25 UTC)
Expired
Jan 12, 2013, 11:30 PM CST
In force
2 hr
Issued by
the Storm Prediction Center
All 42 counties

Arkansas County, AR, Bradley County, AR, Calhoun County, AR, Clark County, AR, Clay County, AR, Cleveland County, AR, Columbia County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Dallas County, AR, Drew County, AR, Faulkner County, AR, Grant County, AR, Greene County, AR, Hempstead County, AR, Hot Spring County, AR, Jackson County, AR, Jefferson County, AR, Lafayette County, AR, Lee County, AR, Lincoln County, AR, Lonoke County, AR, Miller County, AR, Mississippi County, AR, Monroe County, AR, Nevada County, AR, Ouachita County, AR, Phillips County, AR, Poinsett County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, St. Francis County, AR, Union County, AR, White County, AR, Woodruff County, AR, Fulton County, KY, Dunklin County, MO, New Madrid County, MO, Pemiscot County, MO, Lake County, TN

The radar

The Little Rock radar (KLZK), 42 km from the middle of the area, began a volume at 03:25 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

Little Rock, AR (KLZK), launched 00:00Z, 3.4 hours before the alert went out and 174 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-pSkew-T log-p diagram, Little Rock, AR at 00:00Z on 2013-01-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 924 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Little Rock, AR at 00:00Z on 2013-01-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 485 square meters per square second.1939587897117Sfc1 km3 km6 km9 kmRMLM
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
924 J/kg
Mixed-layer CIN
-1 J/kg
Mixed-layer LCL
568 m above ground
0-6 km bulk shear
74 kt
0-1 km storm-relative helicity
485 m²/s²
0-3 km storm-relative helicity
531 m²/s²
Significant tornado parameter
3.3
Supercell composite
15.7

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.

IssuedProductOfficeCountiesLasted
Jan 12, 6:18 PM CSTMesoscale DiscussionSPCArkansas, Bradley, Calhoun, Clark, Clay, Cleburne and 48 more117 min
Jan 12, 10:33 PM CSTMesoscale DiscussionSPCAshley, Bradley, Calhoun, Columbia, Drew, Ouachita and 1 more87 min
Jan 12, 11:29 PM CSTTornado WatchSPCArkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 9 more5 hr
Jan 13, 1:18 AM CSTMesoscale DiscussionSPCAshley, Chicot, Desha, Drew87 min
Jan 13, 3:53 AM CSTMesoscale DiscussionSPCArkansas, Ashley, Bradley, Chicot, Desha, Drew and 5 more97 min
Jan 12, 10:47 PM CSTMesoscale DiscussionSPCBoone, Campbell, Carroll, Gallatin, Henderson, Kenton and 1 more88 min
Jan 13, 2:46 PM CSTMesoscale DiscussionSPCAdair, Allen, Barren, Cumberland, Metcalfe, Monroe and 2 more119 min
Jan 12, 6:17 PM CSTMesoscale DiscussionSPCChristian, Crawford, Dent, Douglas, Franklin, Gasconade and 22 more6 hr
Jan 13, 10:11 AM CSTMesoscale DiscussionSPCBedford, Cannon, Cheatham, Coffee, Davidson, DeKalb and 14 more94 min

Nearby

Mesoscale Discussions in Arkansas, 2013Mesoscale Discussions in Missouri, 2013Mesoscale Discussions in Kentucky, 2013Every 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.