Alert archive / Texas / Mesoscale Discussions in 2020

Mesoscale Discussion 494

April 28, 20204 counties in Arkansas; Bossier Parish, Caddo Parish, Louisiana; 50 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2020, 8:06 PM CDT for 4 counties in Arkansas; Bossier Parish, Caddo Parish, Louisiana; 50 counties in Texas. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued
Apr 28, 2020, 8:06 PM CDT (01:06 UTC)
Expired
Apr 28, 2020, 9:00 PM CDT
In force
54 min
Issued by
the Storm Prediction Center
Chance of a watch
95%
All 56 counties

Lafayette County, AR, Little River County, AR, Miller County, AR, Sevier County, AR, Bossier Parish, LA, Caddo Parish, LA, Anderson County, TX, Bosque County, TX, Bowie County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Collin County, TX, Coryell County, TX, Dallas County, TX, Delta County, TX, Denton County, TX, Ellis County, TX, Erath County, TX, Falls County, TX, Fannin County, TX, Franklin County, TX, Freestone County, TX, Gregg County, TX, Hamilton County, TX, Harrison County, TX, Henderson County, TX, Hill County, TX, Hood County, TX, Hopkins County, TX, Hunt County, TX, Johnson County, TX, Kaufman County, TX, Lamar County, TX, Leon County, TX, Limestone County, TX, Marion County, TX, McLennan County, TX, Morris County, TX, Navarro County, TX, Palo Pinto County, TX, Panola County, TX, Parker County, TX, Rains County, TX, Red River County, TX, Robertson County, TX, Rockwall County, TX, Rusk County, TX, Smith County, TX, Somervell County, TX, Tarrant County, TX, Titus County, TX, Upshur County, TX, Van Zandt County, TX, Wise County, TX, Wood County, TX

The radar

The Dallas/Ft Worth radar (KFWS), 77 km from the middle of the area, began a volume at 01:07 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

Fort Worth, TX (KFWD), launched 00:00Z, 1.1 hours before the alert went out and 78 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, Fort Worth, TX at 00:00Z on 2020-04-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3210 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, Fort Worth, TX at 00:00Z on 2020-04-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 155 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
3210 J/kg
Mixed-layer CIN
-92 J/kg
Mixed-layer LCL
1442 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
155 m²/s²
0-3 km storm-relative helicity
248 m²/s²
Significant tornado parameter
1.0
Supercell composite
17.8

Open this sounding in Storm Lab

The text

As transmitted.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 28, 7:35 PM CDTSevere Thunderstorm WatchSPCArkansas, Baxter, Boone, Bradley, Calhoun, Clark and 51 more7 hr
Apr 28, 8:25 PM CDTSevere Thunderstorm WatchSPCColumbia, Hempstead, Howard, Lafayette, Little River, Miller and 3 more9 hr
Apr 28, 10:08 PM CDTMesoscale DiscussionSPCClark, Cleburne, Conway, Craighead, Faulkner, Garland and 15 more97 min
Apr 28, 11:12 PM CDTMesoscale DiscussionSPCArkansas, Bradley, Calhoun, Cleveland, Crittenden, Cross and 11 more63 min
Apr 28, 11:57 PM CDTMesoscale DiscussionSPCAshley, Chicot63 min
Apr 29, 12:48 AM CDTSevere Thunderstorm WatchSPCAshley, Chicot4 hr
Apr 29, 1:56 AM CDTMesoscale DiscussionSPCAllen, Avoyelles, Beauregard, Bienville, Caldwell, Catahoula and 19 more2 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

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.