Alert archive / Texas / Mesoscale Discussions in 2017

Mesoscale Discussion 696

May 11, 20174 states

The Storm Prediction Center issued this mesoscale discussion at May 11, 2017, 1:37 PM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
May 11, 2017, 1:37 PM CDT (18:37 UTC)
Expired
May 11, 2017, 4:00 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
80%
All 46 counties

Hempstead County, AR, Howard County, AR, Lafayette County, AR, Little River County, AR, Miller County, AR, Sevier County, AR, Bossier Parish, LA, Caddo Parish, LA, McCurtain County, OK, Anderson County, TX, Angelina County, TX, Bowie County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Delta County, TX, Falls County, TX, Franklin County, TX, Freestone County, TX, Gregg County, TX, Harrison County, TX, Henderson County, TX, Hopkins County, TX, Houston County, TX, Kaufman County, TX, Lamar County, TX, Leon County, TX, Limestone County, TX, Madison County, TX, Marion County, TX, Morris County, TX, Nacogdoches County, TX, Navarro County, TX, Panola County, TX, Rains County, TX, Red River County, TX, Robertson County, TX, Rusk County, TX, Shelby County, TX, Smith County, TX, Titus County, TX, Trinity County, TX, Upshur County, TX, Van Zandt County, TX, Walker County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 127 km from the middle of the area, began a volume at 18:41 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, 6.6 hours before the alert went out and 135 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 2017-05-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 15 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 2017-05-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 131 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
15 J/kg
Mixed-layer CIN
-373 J/kg
Mixed-layer LCL
755 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
131 m²/s²
0-3 km storm-relative helicity
135 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.

IssuedProductOfficeCountiesLasted
May 11, 12:56 PM CDTSevere Thunderstorm WatchSPCBenton, Carroll, Crawford, Franklin, Madison, Sebastian and 1 more8 hr
May 11, 2:43 PM CDTSevere Thunderstorm WatchSPCColumbia, Hempstead, Howard, Lafayette, Little River, Miller and 3 more9 hr
May 11, 2:49 PM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Clark, Cleburne and 34 more116 min
May 11, 3:17 PM CDTSevere Thunderstorm WatchSPCArkansas, Baxter, Boone, Bradley, Calhoun, Clark and 45 more7 hr
May 11, 5:49 PM CDTMesoscale DiscussionSPCArkansas, Baxter, Boone, Bradley, Calhoun, Carroll and 56 more56 min
May 11, 6:07 PM CDTMesoscale DiscussionSPCBenton, Washington83 min
May 11, 6:20 PM CDTMesoscale DiscussionSPCCaddo115 min
May 11, 11:44 AM CDTMesoscale DiscussionSPCAdair, Alfalfa, Blaine, Canadian, Cherokee, Craig and 38 more3 hr
May 10, 8:31 PM CDTMesoscale DiscussionSPCCallahan, Coke, Coleman, Concho, Crockett, Edwards and 15 more119 min

Nearby

Mesoscale Discussions in Texas, 2017Mesoscale Discussions in Arkansas, 2017Mesoscale Discussions in Louisiana, 2017Every mesoscale discussion in 2017

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.