Alert archive / Alabama / Dense Fog Advisories in 2021

Dense Fog Advisory 6, NWS Birmingham, AL

July 24, 202139 counties in Alabama

NWS Birmingham, AL issued this dense fog advisory at Jul 24, 2021, 4:03 AM CDT for 39 counties in Alabama. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued: Jul 24, 2021, 4:03 AM CDT (09:03 UTC)
Expired: Jul 24, 2021, 9:00 AM CDT
In force: 5 hr
Issued by: NWS Birmingham, AL

All 39 counties

Autauga County, AL, Barbour County, AL, Bibb County, AL, Blount County, AL, Bullock County, AL, Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Dallas County, AL, Elmore County, AL, Etowah County, AL, Fayette County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lamar County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Marengo County, AL, Marion County, AL, Montgomery County, AL, Perry County, AL, Pickens County, AL, Pike County, AL, Randolph County, AL, Russell County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL

The radar

The Birmingham radar (KBMX), 22 km from the middle of the area, began a volume at 09:04 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

Birmingham, AL (KBMX), launched 00:00Z, 9.1 hours before the alert went out and 23 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 609 J/kg
Mixed-layer CIN: -74 J/kg
Mixed-layer LCL: 1358 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: 4 m²/s²
0-3 km storm-relative helicity: -49 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this dense fog advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Birmingham, AL wrote its last area forecast discussion before this dense fog advisory went out at Jul 24, 3:42 AM CDT, 21 minutes earlier.

Area forecast discussion, Jul 24, 3:42 AM CDT, 21 minutes before

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Hazardous weather outlook, Jul 24, 3:44 AM CDT, 19 minutes before

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  <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>
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        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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The office that day

Everything else NWS Birmingham, AL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 23, 7:08 PM CDT	Areal Flood Advisory	BMX	Greene, Hale, Tuscaloosa	92 min
Jul 23, 8:55 PM CDT	Special Weather Statement	BMX	Dallas	50 min

Nearby

Dense Fog Advisories in Alabama, 2021 Every dense fog advisory in 2021

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.