Alert archive / Alabama / Mesoscale Discussions in 2011

Mesoscale Discussion 640

April 27, 201132 counties in Alabama; 7 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2011, 6:39 PM CDT for 32 counties in Alabama; 7 counties in Georgia. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued
Apr 27, 2011, 6:39 PM CDT (23:39 UTC)
Expired
Apr 27, 2011, 7:45 PM CDT
In force
66 min
Issued by
the Storm Prediction Center
All 39 counties

Autauga County, AL, Bibb County, AL, Blount County, AL, Calhoun County, AL, Cherokee County, AL, Chilton County, AL, Choctaw County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Cullman County, AL, Dallas County, AL, DeKalb County, AL, Etowah County, AL, Fayette County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lowndes County, AL, Marengo County, AL, Marshall County, AL, Morgan County, AL, Perry County, AL, Pickens County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tuscaloosa County, AL, Walker County, AL, Wilcox County, AL, Winston County, AL, Bartow County, GA, Chattooga County, GA, Floyd County, GA, Gordon County, GA, Haralson County, GA, Pickens County, GA, Polk County, GA

The radar

The Birmingham radar (KBMX), 37 km from the middle of the area, began a volume at 23:41 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

Birmingham, AL (KBMX), launched 12:00Z, 11.7 hours before the alert went out and 36 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, Birmingham, AL at 12:00Z on 2011-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 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, Birmingham, AL at 12:00Z on 2011-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -359 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
587 m above ground
0-6 km bulk shear
60 kt
0-1 km storm-relative helicity
-359 m²/s²
0-3 km storm-relative helicity
-197 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

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
Apr 26, 7:59 PM CDTMesoscale DiscussionSPCColbert, Franklin, Lamar, Lauderdale, Lawrence, Limestone and 1 more2 hr
Apr 26, 9:33 PM CDTTornado Watch PDSSPCColbert, Franklin, Lauderdale7 hr
Apr 26, 11:33 PM CDTMesoscale DiscussionSPCColbert, Franklin, Lamar, Lauderdale, Marion117 min
Apr 27, 1:56 AM CDTMesoscale DiscussionSPCBibb, Blount, Cullman, Fayette, Greene, Hale and 12 more64 min
Apr 27, 2:26 AM CDTTornado WatchSPCBibb, Blount, Calhoun, Cherokee, Chilton, Clay and 29 more6 hr
Apr 27, 8:08 AM CDTTornado WatchSPCColbert, Cullman, DeKalb, Fayette, Franklin, Jackson and 10 more6 hr
Apr 27, 10:45 AM CDTMesoscale DiscussionSPCGreene, Lamar, Marion, Pickens, Sumter90 min
Apr 27, 11:39 AM CDTMesoscale DiscussionSPCCullman, DeKalb, Jackson, Madison, Marshall, Morgan66 min
Apr 27, 1:05 PM CDTMesoscale DiscussionSPCBibb, Blount, Calhoun, Cherokee, Chilton, Choctaw and 27 more85 min
Apr 27, 1:42 PM CDTTornado Watch PDSSPCAutauga, Bibb, Blount, Butler, Calhoun, Cherokee and 41 more8 hr
Apr 27, 2:56 PM CDTMesoscale DiscussionSPCBibb, Blount, Calhoun, Cherokee, Chilton, Choctaw and 33 more2 hr
Apr 27, 5:01 PM CDTMesoscale DiscussionSPCAutauga, Bibb, Blount, Butler, Calhoun, Cherokee and 38 more89 min
Apr 27, 5:41 PM CDTMesoscale DiscussionSPCBarbour, Bullock, Chambers, Crenshaw, Elmore, Lee and 6 more34 min
Apr 27, 5:52 PM CDTTornado Watch PDSSPCBarbour, Bullock, Chambers, Elmore, Lee, Macon and 5 more9 hr
Apr 27, 6:19 AM CDTMesoscale DiscussionSPCBartow, Carroll, Chattooga, Cherokee, Clayton, Cobb and 22 more56 min
Apr 27, 6:48 AM CDTTornado WatchSPCBartow, Butts, Carroll, Catoosa, Chattooga, Cherokee and 36 more2 hr

Nearby

Mesoscale Discussions in Alabama, 2011Mesoscale Discussions in Georgia, 2011Every mesoscale discussion in 2011

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.