Alert archive / Arkansas / Mesoscale Discussions in 2011

Mesoscale Discussion 827

May 20, 20114 states

The Storm Prediction Center issued this mesoscale discussion at May 20, 2011, 1:28 PM CDT for 4 states. It was in force for 62 min.

The area

The outline as issued.

The facts

Issued
May 20, 2011, 1:28 PM CDT (18:28 UTC)
Expired
May 20, 2011, 2:30 PM CDT
In force
62 min
Issued by
the Storm Prediction Center
All 80 counties

Baxter County, AR, Boone County, AR, Calhoun County, AR, Carroll County, AR, Clark County, AR, Cleburne County, AR, Columbia County, AR, Conway County, AR, Crawford County, AR, Dallas County, AR, Faulkner County, AR, Franklin County, AR, Garland County, AR, Grant County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Jefferson County, AR, Johnson County, AR, Lafayette County, AR, Lincoln County, AR, Little River County, AR, Logan County, AR, Lonoke County, AR, Madison County, AR, Marion County, AR, Miller County, AR, Montgomery County, AR, Nevada County, AR, Newton County, AR, Ouachita County, AR, Perry County, AR, Pike County, AR, Polk County, AR, Pope County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, Scott County, AR, Searcy County, AR, Sebastian County, AR, Sevier County, AR, Sharp County, AR, Stone County, AR, Union County, AR, Van Buren County, AR, Washington County, AR, White County, AR, Woodruff County, AR, Yell County, AR, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, Webster Parish, LA, Adair County, OK, Cherokee County, OK, Choctaw County, OK, Haskell County, OK, Latimer County, OK, LeFlore County, OK, McCurtain County, OK, Pushmataha County, OK, Sequoyah 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, Smith County, TX, Titus County, TX, Upshur County, TX, Wood County, TX

The radar

The Western Arkansas radar (KSRX), 138 km from the middle of the area, began a volume at 18:31 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 nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 6.5 hours before the alert went out and 179 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, Shreveport, LA at 12:00Z on 2011-05-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2656 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, Shreveport, LA at 12:00Z on 2011-05-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 151 square meters per square second.193958Sfc1 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
2656 J/kg
Mixed-layer CIN
-44 J/kg
Mixed-layer LCL
648 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
151 m²/s²
0-3 km storm-relative helicity
231 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
May 20, 9:11 AM CDTMesoscale DiscussionSPCBenton, Washington2 hr
May 20, 10:30 AM CDTMesoscale DiscussionSPCArkansas, Baxter, Boone, Bradley, Calhoun, Carroll and 53 more60 min
May 20, 11:03 AM CDTTornado WatchSPCClark, Columbia, Conway, Crawford, Dallas, Franklin and 26 more7 hr
May 20, 4:00 PM CDTMesoscale DiscussionSPCCalhoun, Clark, Columbia, Conway, Dallas, Faulkner and 24 more60 min
May 20, 5:56 PM CDTTornado WatchSPCClark, Columbia, Dallas, Garland, Grant, Hempstead and 16 more3 hr
May 19, 7:47 PM CDTMesoscale DiscussionSPCCaddo, Canadian, Comanche, Cotton, Grady, Kiowa and 1 more118 min
May 19, 11:39 PM CDTSevere Thunderstorm WatchSPCHarmon, Jackson, Tillman6 hr
May 20, 2:58 AM CDTMesoscale DiscussionSPCComanche, Jackson, Kiowa, Tillman, Washita92 min
May 20, 1:52 PM CDTMesoscale DiscussionSPCEllis, Harper, Woods, Woodward113 min
May 20, 2:32 PM CDTSevere Thunderstorm WatchSPCAlfalfa, Ellis, Garfield, Grant, Harper, Major and 2 more7 hr
May 20, 6:01 PM CDTMesoscale DiscussionSPCAlfalfa, Ellis, Garfield, Grant, Harper, Major and 2 more59 min
May 19, 9:36 PM CDTMesoscale DiscussionSPCBorden, Briscoe, Childress, Coke, Collingsworth, Cottle and 28 more84 min
May 20, 12:08 PM CDTMesoscale DiscussionSPCAnderson, Bandera, Bastrop, Bell, Blanco, Bosque and 56 more67 min
May 20, 12:28 PM CDTSevere Thunderstorm WatchSPCAnderson, Bandera, Bastrop, Bell, Bexar, Blanco and 60 more10 hr
May 20, 5:34 PM CDTMesoscale DiscussionSPCAnderson, Bandera, Bastrop, Bell, Bexar, Blanco and 41 more116 min

Nearby

Mesoscale Discussions in Arkansas, 2011Mesoscale Discussions in Texas, 2011Mesoscale Discussions in Oklahoma, 2011Every 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.