Alert archive / Alabama / Mesoscale Discussions in 2009

Mesoscale Discussion 658

May 1, 200916 counties in Alabama; Tishomingo County, Mississippi; 6 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at May 1, 2009, 3:48 PM CDT for 16 counties in Alabama; Tishomingo County, Mississippi; 6 counties in Tennessee. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued
May 1, 2009, 3:48 PM CDT (20:48 UTC)
Expired
May 1, 2009, 5:15 PM CDT
In force
87 min
Issued by
the Storm Prediction Center
All 23 counties

Blount County, AL, Colbert County, AL, Cullman County, AL, DeKalb County, AL, Etowah County, AL, Franklin County, AL, Jackson County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marion County, AL, Marshall County, AL, Morgan County, AL, Walker County, AL, Winston County, AL, Tishomingo County, MS, Giles County, TN, Hardin County, TN, Lawrence County, TN, Lewis County, TN, Lincoln County, TN, Wayne County, TN

The radar

The Northeast Alabama radar (KHTX), 108 km from the middle of the area, began a volume at 20:49 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

Nashville Metro, TN (KBNA), launched 12:00Z, 8.8 hours before the alert went out and 166 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, Nashville Metro, TN at 12:00Z on 2009-05-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 470 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, Nashville Metro, TN at 12:00Z on 2009-05-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 110 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
470 J/kg
Mixed-layer CIN
-13 J/kg
Mixed-layer LCL
460 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
110 m²/s²
0-3 km storm-relative helicity
132 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

<!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
May 1, 1:18 PM CDTMesoscale DiscussionSPCBlount, Colbert, Cullman, DeKalb, Franklin, Jackson and 9 more87 min
May 1, 2:23 PM CDTSevere Thunderstorm WatchSPCColbert, Cullman, DeKalb, Franklin, Jackson, Lauderdale and 5 more5 hr
May 1, 6:41 PM CDTMesoscale DiscussionSPCColbert, DeKalb, Franklin, Jackson, Lauderdale, Lawrence and 6 more64 min
May 1, 3:21 PM CDTMesoscale DiscussionSPCCarroll, Chester, Crockett, Dyer, Fayette, Gibson and 10 more54 min
May 1, 3:36 PM CDTSevere Thunderstorm WatchSPCCarroll, Chester, Crockett, Decatur, Dyer, Fayette and 14 more6 hr
May 1, 6:11 PM CDTMesoscale DiscussionSPCCarroll, Chester, Crockett, Dyer, Fayette, Gibson and 11 more64 min

Nearby

Mesoscale Discussions in Alabama, 2009Mesoscale Discussions in Tennessee, 2009Mesoscale Discussions in Mississippi, 2009Every mesoscale discussion in 2009

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.