Alert archive / Arkansas / Mesoscale Discussions in 2013

Mesoscale Discussion 519

April 18, 201326 counties in Arkansas; 15 counties in Missouri; Lake County, Tennessee

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2013, 7:26 AM CDT for 26 counties in Arkansas; 15 counties in Missouri; Lake County, Tennessee. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 18, 2013, 7:26 AM CDT (12:26 UTC)
Expired
Apr 18, 2013, 9:30 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
60%
All 42 counties

Baxter County, AR, Boone County, AR, Clay County, AR, Cleburne County, AR, Conway County, AR, Craighead County, AR, Faulkner County, AR, Fulton County, AR, Greene County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Johnson County, AR, Lawrence County, AR, Logan County, AR, Marion County, AR, Newton County, AR, Perry County, AR, Poinsett County, AR, Pope County, AR, Randolph County, AR, Searcy County, AR, Sharp County, AR, Stone County, AR, Van Buren County, AR, White County, AR, Bollinger County, MO, Butler County, MO, Cape Girardeau County, MO, Carter County, MO, Dunklin County, MO, Howell County, MO, New Madrid County, MO, Oregon County, MO, Ozark County, MO, Pemiscot County, MO, Ripley County, MO, Scott County, MO, Shannon County, MO, Stoddard County, MO, Wayne County, MO, Lake County, TN

The radar

The Little Rock radar (KLZK), 148 km from the middle of the area, began a volume at 12:27 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

Springfield, MO (KSGF), launched 12:00Z, 0.4 hours before the alert went out and 192 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, Springfield, MO at 12:00Z on 2013-04-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 13 joules per kilogram.LCLLFCEL10008507005003002001001 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, Springfield, MO at 12:00Z on 2013-04-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 132 square meters per square second.1939587897Sfc1 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
13 J/kg
Mixed-layer CIN
-167 J/kg
Mixed-layer LCL
1125 m above ground
0-6 km bulk shear
55 kt
0-1 km storm-relative helicity
132 m²/s²
0-3 km storm-relative helicity
220 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.

IssuedProductOfficeCountiesLasted
Apr 17, 10:47 PM CDTTornado WatchSPCBenton, Carroll, Crawford, Madison, Washington7 hr
Apr 18, 2:01 AM CDTMesoscale DiscussionSPCBenton, Boone, Carroll, Crawford, Franklin, Madison and 2 more89 min
Apr 18, 4:02 AM CDTMesoscale DiscussionSPCBaxter, Boone, Carroll, Conway, Crawford, Franklin and 17 more58 min
Apr 18, 9:25 AM CDTTornado WatchSPCArkansas, Baxter, Bradley, Calhoun, Clark, Clay and 43 more8 hr
Apr 18, 12:48 PM CDTMesoscale DiscussionSPCArkansas, Ashley, Bradley, Calhoun, Chicot, Clay and 29 more87 min
Apr 18, 1:43 PM CDTTornado WatchSPCAshley, Chicot, Union8 hr
Apr 17, 8:53 PM CDTMesoscale DiscussionSPCAudrain, Barry, Barton, Bates, Benton, Boone and 48 more97 min
Apr 17, 9:57 PM CDTTornado WatchSPCAudrain, Barry, Barton, Benton, Boone, Callaway and 34 more7 hr
Apr 17, 11:46 PM CDTMesoscale DiscussionSPCAudrain, Barry, Barton, Benton, Boone, Callaway and 32 more89 min
Apr 18, 5:36 AM CDTMesoscale DiscussionSPCJefferson, Sainte Genevieve, Saint Francois, Saint Louis, Washington, City of Saint Louis54 min
Apr 18, 5:42 AM CDTTornado WatchSPCIron, Jefferson, Madison, Reynolds, Saint Charles, Sainte Genevieve and 4 more8 hr
Apr 18, 11:14 AM CDTMesoscale DiscussionSPCIron, Madison, Sainte Genevieve, Saint Francois2 hr

Nearby

Mesoscale Discussions in Arkansas, 2013Mesoscale Discussions in Missouri, 2013Mesoscale Discussions in Tennessee, 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.