Alert archive / Louisiana / Mesoscale Discussions in 2020

Mesoscale Discussion 406

April 19, 202020 parishes in Louisiana; Adams County, Wilkinson County, Mississippi; Sabine County, San Augustine County, Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 19, 2020, 12:47 PM CDT for 20 parishes in Louisiana; Adams County, Wilkinson County, Mississippi; Sabine County, San Augustine County, Texas. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued
Apr 19, 2020, 12:47 PM CDT (17:47 UTC)
Expired
Apr 19, 2020, 1:45 PM CDT
In force
58 min
Issued by
the Storm Prediction Center
All 24 counties

Avoyelles 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, Madison 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, Winn Parish, LA, Adams County, MS, Wilkinson County, MS, Sabine County, TX, San Augustine County, TX

The radar

The Ft Polk radar (KPOE), 66 km from the middle of the area, began a volume at 17:50 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 12:00Z, 5.8 hours before the alert went out and 116 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 2020-04-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 561 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 2020-04-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 298 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
561 J/kg
Mixed-layer CIN
-198 J/kg
Mixed-layer LCL
551 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
298 m²/s²
0-3 km storm-relative helicity
227 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.0

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
Apr 18, 8:27 PM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, Claiborne, De Soto, Red River and 1 more2 hr
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, 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, 2:34 AM CDTMesoscale DiscussionSPCAttala, Bolivar, Calhoun, Carroll, Chickasaw, Choctaw and 29 more116 min
Apr 19, 3:56 PM CDTTornado WatchSPCGeorge, Greene, Perry, Stone, Wayne6 hr
Apr 19, 7:22 AM CDTMesoscale DiscussionSPCAnderson, Angelina, Austin, Bastrop, Bell, Brazoria and 52 more113 min
Apr 19, 11:19 AM CDTMesoscale DiscussionSPCBowie, Camp, Cass, Collin, Dallas, Delta and 16 more116 min

Nearby

Mesoscale Discussions in Louisiana, 2020Mesoscale Discussions in Mississippi, 2020Mesoscale Discussions in Texas, 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.