Alert archive / Oklahoma / Mesoscale Discussions in 2011

Mesoscale Discussion 471

April 19, 201110 counties in Arkansas; 17 counties in Oklahoma; 16 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 19, 2011, 1:40 PM CDT for 10 counties in Arkansas; 17 counties in Oklahoma; 16 counties in Texas. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued: Apr 19, 2011, 1:40 PM CDT (18:40 UTC)
Expired: Apr 19, 2011, 2:45 PM CDT
In force: 65 min
Issued by: the Storm Prediction Center

All 43 counties

Benton County, AR, Crawford County, AR, Franklin County, AR, Johnson County, AR, Logan County, AR, Madison County, AR, Polk County, AR, Scott County, AR, Sebastian County, AR, Washington County, AR, Adair County, OK, Atoka County, OK, Bryan County, OK, Cherokee County, OK, Choctaw County, OK, Coal County, OK, Haskell County, OK, Johnston County, OK, Latimer County, OK, LeFlore County, OK, Marshall County, OK, McCurtain County, OK, McIntosh County, OK, Muskogee County, OK, Pittsburg County, OK, Pushmataha County, OK, Sequoyah County, OK, Collin County, TX, Dallas County, TX, Delta County, TX, Denton County, TX, Ellis County, TX, Fannin County, TX, Franklin County, TX, Grayson County, TX, Hopkins County, TX, Hunt County, TX, Kaufman County, TX, Lamar County, TX, Rains County, TX, Red River County, TX, Rockwall County, TX, Van Zandt County, TX

The radar

The Western Arkansas radar (KSRX), 132 km from the middle of the area, began a volume at 18:44 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 155Apr 19, 2:20 PM CDT

The nearest sounding before it

Norman, OK (KOUN), launched 12:00Z, 6.7 hours before the alert went out and 213 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: 2660 J/kg
Mixed-layer CIN: -211 J/kg
Mixed-layer LCL: 1094 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 558 m²/s²
0-3 km storm-relative helicity: 577 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 11.5

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 19, 12:40 PM CDT	Mesoscale Discussion	SPC	Benton	95 min
Apr 19, 2:16 PM CDT	Tornado Watch	SPC	Baxter, Benton, Boone, Carroll, Columbia, Conway and 29 more	10 hr
Apr 19, 6:24 PM CDT	Mesoscale Discussion	SPC	Arkansas, Clay, Cleveland, Craighead, Cross, Dallas and 19 more	66 min
Apr 19, 6:46 PM CDT	Tornado Watch	SPC	Arkansas, Bradley, Calhoun, Clark, Clay, Cleburne and 35 more	9 hr
Apr 19, 3:45 PM CDT	Mesoscale Discussion	SPC	Bastrop, Bell, Bexar, Blanco, Bosque, Burleson and 24 more	60 min
Apr 19, 5:44 PM CDT	Severe Thunderstorm Watch	SPC	Anderson, Bell, Blanco, Bosque, Burnet, Coryell and 19 more	4 hr

Nearby

Mesoscale Discussions in Oklahoma, 2011 Mesoscale Discussions in Texas, 2011 Mesoscale Discussions in Arkansas, 2011 Every mesoscale discussion in 2011

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.