Alert archive / Pennsylvania / Mesoscale Discussions in 2008

Mesoscale Discussion 1844

July 21, 20086 counties in Ohio; 9 counties in Pennsylvania; Brooke County, Hancock County, West Virginia

The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2008, 6:33 PM EDT for 6 counties in Ohio; 9 counties in Pennsylvania; Brooke County, Hancock County, West Virginia. It was in force for 57 min.

The area

The outline as issued.

The facts

Issued: Jul 21, 2008, 6:33 PM EDT (22:33 UTC)
Expired: Jul 21, 2008, 7:30 PM EDT
In force: 57 min
Issued by: the Storm Prediction Center

Counties Carroll County, OH, Columbiana County, OH, Harrison County, OH, Jefferson County, OH, Mahoning County, OH, Tuscarawas County, OH, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Butler County, PA, Clarion County, PA, Lawrence County, PA, Mercer County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV

The radar

The Pittsburgh radar (KPBZ), 22 km from the middle of the area, began a volume at 22:33 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

Pittsburgh, PA (KPIT), launched 12:00Z, 10.6 hours before the alert went out and 38 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: 923 J/kg
Mixed-layer CIN: -13 J/kg
Mixed-layer LCL: 710 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 95 m²/s²
0-3 km storm-relative helicity: 134 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.4

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.

Issued	Product	Office	Counties	Lasted
Jul 21, 9:24 AM EDT	Severe Thunderstorm Watch	SPC	Allen, Defiance, Fulton, Henry, Paulding, Putnam and 2 more	4 hr
Jul 21, 10:28 AM EDT	Mesoscale Discussion	SPC	Ashland, Belmont, Carroll, Columbiana, Coshocton, Crawford and 31 more	62 min
Jul 21, 11:37 AM EDT	Severe Thunderstorm Watch	SPC	Adams, Ashland, Auglaize, Brown, Butler, Champaign and 47 more	6 hr
Jul 21, 3:20 PM EDT	Mesoscale Discussion	SPC	Ashland, Coshocton, Fairfield, Geauga, Hocking, Holmes and 10 more	55 min
Jul 21, 2:09 PM EDT	Mesoscale Discussion	SPC	Bradford, Susquehanna, Wayne, Wyoming	66 min

Nearby

Mesoscale Discussions in Pennsylvania, 2008 Mesoscale Discussions in Ohio, 2008 Mesoscale Discussions in West Virginia, 2008 Every mesoscale discussion in 2008

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.