Alert archive / Texas / Mesoscale Discussions in 2020

Mesoscale Discussion 500

April 29, 202025 parishes in Louisiana; 34 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 29, 2020, 1:56 AM CDT for 25 parishes in Louisiana; 34 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 29, 2020, 1:56 AM CDT (06:56 UTC)
Expired
Apr 29, 2020, 4:00 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 59 counties

Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, De Soto Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, Vernon Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Anderson County, TX, Angelina County, TX, Bell County, TX, Bosque County, TX, Brazos County, TX, Burleson County, TX, Cherokee County, TX, Coryell County, TX, Falls County, TX, Freestone County, TX, Grimes County, TX, Houston County, TX, Jasper County, TX, Lee County, TX, Leon County, TX, Limestone County, TX, Madison County, TX, McLennan County, TX, Milam County, TX, Montgomery County, TX, Nacogdoches County, TX, Newton County, TX, Polk County, TX, Robertson County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Williamson County, TX

The radar

The Shreveport radar (KSHV), 154 km from the middle of the area, began a volume at 06:57 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 (KSHV), launched 00:00Z, 6.9 hours before the alert went out and 163 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 00:00Z on 2020-04-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 733 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 00:00Z on 2020-04-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 119 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
733 J/kg
Mixed-layer CIN
-250 J/kg
Mixed-layer LCL
1058 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
119 m²/s²
0-3 km storm-relative helicity
217 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

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 28, 8:06 PM CDTMesoscale DiscussionSPCBossier, Caddo54 min
Apr 28, 8:25 PM CDTSevere Thunderstorm WatchSPCBienville, Bossier, Caddo, Claiborne, De Soto, Red River and 2 more9 hr
Apr 28, 11:57 PM CDTMesoscale DiscussionSPCCaldwell, East Carroll, Franklin, Jackson, Madison, Morehouse and 5 more63 min
Apr 29, 12:48 AM CDTSevere Thunderstorm WatchSPCCaldwell, Catahoula, Concordia, East Carroll, Franklin, Grant and 12 more4 hr
Apr 29, 2:40 AM CDTSevere Thunderstorm WatchSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 23 more6 hr
Apr 29, 5:05 AM CDTMesoscale DiscussionSPCCalcasieu, Cameron115 min
Apr 28, 9:04 PM CDTMesoscale DiscussionSPCJim Hogg, Starr, Zapata116 min
Apr 28, 10:08 PM CDTMesoscale DiscussionSPCCollin, Cooke, Dallas, Delta, Denton, Fannin and 11 more97 min

Nearby

Mesoscale Discussions in Texas, 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.