Alert archive / North Carolina / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 99, NWS Greenville-Spartanburg, SC

May 21, 2020Union County, North Carolina

NWS Greenville-Spartanburg, SC issued this severe thunderstorm warning at May 21, 2020, 1:12 PM EDT for Union County, North Carolina. It was in force for 33 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 21, 2020, 1:12 PM EDT (17:12 UTC)
Expired: May 21, 2020, 1:45 PM EDT
In force: 33 min
Issued by: NWS Greenville-Spartanburg, SC
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Union County, NC

The radar

The Columbia radar (KCAE), 128 km from the middle of the area, began a volume at 17:12 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 5.2 hours before the alert went out and 134 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: 1 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 451 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 501 m²/s²
0-3 km storm-relative helicity: 618 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

What forecasters said that day

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

NWS Greenville-Spartanburg, SC wrote its last area forecast discussion before this severe thunderstorm warning went out at May 21, 10:59 AM EDT, 2 hours 13 minutes earlier.

Area forecast discussion, May 21, 10:59 AM EDT, 2 hours 13 minutes before

<!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>

Hazardous weather outlook, May 21, 9:29 AM EDT, 3 hours 43 minutes before

<!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>

In the hours before

Local storm report, May 21, 7:56 AM EDT, 5 hours 16 minutes before

<!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>

Local storm report, May 21, 8:51 AM EDT, 4 hours 21 minutes before

<!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>

Local storm report, May 21, 9:24 AM EDT, 3 hours 48 minutes before

<!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>

Local storm report, May 21, 9:39 AM EDT, 3 hours 33 minutes before

<!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>

Local storm report, May 21, 12:10 PM EDT, 1 hour 2 minutes before

<!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>

The office that day

Everything else NWS Greenville-Spartanburg, SC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 20, 10:37 PM EDT	River Flood Advisory	GSP	Madison	8 hr
May 21, 12:51 AM EDT	River Flood Advisory	GSP	Buncombe, Henderson	49 hr
May 21, 1:17 AM EDT	Areal Flood Warning	GSP	Cabarrus	45 hr
May 21, 1:51 AM EDT	Areal Flood Advisory	GSP	Burke, Caldwell	27 hr
May 21, 3:32 AM EDT	Areal Flood Advisory	GSP	Burke, McDowell	3 days
May 21, 4:33 AM EDT	Areal Flood Advisory	GSP	Cabarrus, Rowan	24 hr
May 21, 8:02 AM EDT	Areal Flood Advisory	GSP	Catawba, Iredell	45 hr
May 21, 12:03 PM EDT	Areal Flood Advisory	GSP	Burke, Caldwell	72 hr
May 21, 1:39 PM EDT	Severe Thunderstorm Warning	GSP	Union	51 min
May 21, 2:02 PM EDT	Areal Flood Warning	GSP	Union	3 hr
May 21, 2:40 PM EDT	Special Weather Statement	GSP	Union	35 min
May 21, 2:57 PM EDT	Special Weather Statement	GSP	Cabarrus	33 min
May 21, 3:43 PM EDT	Special Weather Statement	GSP	Cabarrus	32 min
May 21, 4:11 PM EDT	Special Weather Statement	GSP	Mecklenburg	49 min
May 21, 4:53 PM EDT	Areal Flood Advisory	GSP	Union	3 hr
May 21, 6:47 PM EDT	Areal Flood Warning	GSP	Mecklenburg	3 hr
May 21, 7:26 PM EDT	Areal Flood Warning	GSP	Cabarrus, Mecklenburg	6 hr
May 21, 2:30 AM EDT	Areal Flood Advisory	GSP	Laurens, Spartanburg	26 hr
May 21, 3:10 AM EDT	Areal Flood Advisory	GSP	Elbert	12 hr

Nearby

Severe Thunderstorm Warnings in North Carolina, 2020 Every severe thunderstorm warning 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.