Alert archive / Texas / Mesoscale Discussions in 2020

Mesoscale Discussion 398

April 18, 20204 states

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2020, 8:27 PM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 18, 2020, 8:27 PM CDT (01:27 UTC)
Expired
Apr 18, 2020, 10:30 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
5%
All 42 counties

Columbia County, AR, Hempstead County, AR, Howard County, AR, Lafayette County, AR, Little River County, AR, Miller County, AR, Nevada County, AR, Ouachita County, AR, Pike County, AR, Polk County, AR, Sevier County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Red River Parish, LA, Webster Parish, LA, Choctaw County, OK, McCurtain County, OK, Pushmataha County, OK, Bowie County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Delta County, TX, Franklin County, TX, Gregg County, TX, Harrison County, TX, Hopkins County, TX, Lamar County, TX, Marion County, TX, Morris County, TX, Nacogdoches County, TX, Panola County, TX, Red River County, TX, Rusk County, TX, Shelby County, TX, Smith County, TX, Titus County, TX, Upshur County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 81 km from the middle of the area, began a volume at 01:27 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 nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 1.5 hours before the alert went out and 341 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, Lake Charles Mun, LA at 00:00Z on 2020-04-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 155 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, Lake Charles Mun, LA at 00:00Z on 2020-04-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -30 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
155 J/kg
Mixed-layer CIN
-275 J/kg
Mixed-layer LCL
716 m above ground
0-6 km bulk shear
64 kt
0-1 km storm-relative helicity
-30 m²/s²
0-3 km storm-relative helicity
111 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.6

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
Apr 19, 2:34 AM CDTMesoscale DiscussionSPCArkansas, Ashley, Bradley, Chicot, Cleveland, Desha and 3 more116 min
Apr 19, 11:19 AM CDTMesoscale DiscussionSPCClark, Columbia, Hempstead, Howard, Lafayette, Little River and 7 more116 min
Apr 18, 8:56 PM CDTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Cameron, East Baton Rouge and 26 more2 hr
Apr 19, 8:41 AM CDTTornado WatchSPCAllen, Beauregard, Bienville, Bossier, Caddo, Calcasieu and 18 more6 hr
Apr 19, 10:45 AM CDTMesoscale DiscussionSPCCaldwell, De Soto, Grant, Jackson, LaSalle, Natchitoches and 5 more2 hr
Apr 19, 11:06 AM CDTMesoscale DiscussionSPCAvoyelles, Catahoula, Concordia, Franklin, Madison, Richland and 1 more54 min
Apr 19, 11:45 AM CDTTornado WatchSPCCatahoula, Concordia, East Carroll, Franklin, Madison, Morehouse and 3 more9 hr
Apr 19, 12:39 PM CDTMesoscale DiscussionSPCBeauregard, Calcasieu, Vernon66 min
Apr 19, 12:47 PM CDTMesoscale DiscussionSPCAvoyelles, Bienville, Caldwell, Catahoula, Concordia, De Soto and 14 more58 min
Apr 19, 2:03 PM CDTMesoscale DiscussionSPCAcadia, Allen, Assumption, Avoyelles, Beauregard, Calcasieu and 23 more57 min
Apr 19, 2:39 PM CDTTornado WatchSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 39 more9 hr
Apr 19, 3:07 PM CDTMesoscale DiscussionSPCMadison, Tensas113 min
Apr 19, 5:40 PM CDTMesoscale DiscussionSPCAcadia, Allen, Avoyelles, Beauregard, Calcasieu, Catahoula and 18 more2 hr
Apr 19, 6:37 PM CDTMesoscale DiscussionSPCWashington53 min
Apr 19, 7:22 AM CDTMesoscale DiscussionSPCAnderson, Angelina, Austin, Bastrop, Bell, Brazoria and 52 more113 min

Nearby

Mesoscale Discussions in Texas, 2020Mesoscale Discussions in Arkansas, 2020Mesoscale Discussions in Louisiana, 2020Every mesoscale discussion in 2020

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.