Alert archive / Pennsylvania / Mesoscale Discussions in 2011

Mesoscale Discussion 1689

July 22, 20115 states

The Storm Prediction Center issued this mesoscale discussion at Jul 22, 2011, 3:17 PM EDT for 5 states. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Jul 22, 2011, 3:17 PM EDT (19:17 UTC)
Expired: Jul 22, 2011, 4:15 PM EDT
In force: 58 min
Issued by: the Storm Prediction Center

All 61 counties

Allegany County, MD, Carroll County, MD, Frederick County, MD, Garrett County, MD, Howard County, MD, Montgomery County, MD, Washington County, MD, Belmont County, OH, Carroll County, OH, Columbiana County, OH, Guernsey County, OH, Harrison County, OH, Jefferson County, OH, Mahoning County, OH, Portage County, OH, Stark County, OH, Tuscarawas County, OH, Adams County, PA, Allegheny County, PA, Beaver County, PA, Bedford County, PA, Cambria County, PA, Cumberland County, PA, Fayette County, PA, Franklin County, PA, Fulton County, PA, Greene County, PA, Huntingdon County, PA, Perry County, PA, Somerset County, PA, Washington County, PA, Westmoreland County, PA, York County, PA, Arlington County, VA, City of Fairfax, VA, City of Falls Church, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Loudoun County, VA, Prince William County, VA, Shenandoah County, VA, Warren County, VA, Berkeley County, WV, Brooke County, WV, Grant County, WV, Hampshire County, WV, Hancock County, WV, Hardy County, WV, Jefferson County, WV, Marion County, WV, Marshall County, WV, Mineral County, WV, Monongalia County, WV, Morgan County, WV, Ohio County, WV, Preston County, WV

The radar

The Pittsburgh radar (KPBZ), 135 km from the middle of the area, began a volume at 19:19 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.

Severe Thunderstorm Watch 672Jul 22, 5:40 PM EDT

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 7.3 hours before the alert went out and 120 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: 3887 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 868 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: -61 m²/s²
0-3 km storm-relative helicity: -29 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 22, 5:19 PM EDT	Mesoscale Discussion	SPC	Allegany, Garrett	56 min
Jul 22, 5:37 PM EDT	Severe Thunderstorm Watch	SPC	Garrett	4 hr
Jul 22, 11:20 AM EDT	Mesoscale Discussion	SPC	Allen, Auglaize, Champaign, Clark, Crawford, Darke and 33 more	55 min
Jul 22, 12:50 PM EDT	Mesoscale Discussion	SPC	Allen, Ashland, Auglaize, Champaign, Clark, Clinton and 43 more	55 min
Jul 22, 1:14 PM EDT	Severe Thunderstorm Watch	SPC	Allen, Ashland, Auglaize, Champaign, Clark, Clinton and 45 more	7 hr
Jul 22, 4:32 PM EDT	Mesoscale Discussion	SPC	Allen, Ashland, Auglaize, Champaign, Clark, Clinton and 41 more	88 min
Jul 22, 5:59 PM EDT	Mesoscale Discussion	SPC	Gallia, Lawrence	2 hr
Jul 22, 7:10 PM EDT	Mesoscale Discussion	SPC	Clark, Clinton, Coshocton, Delaware, Fairfield, Fayette and 14 more	35 min

Nearby

Mesoscale Discussions in Pennsylvania, 2011 Mesoscale Discussions in Virginia, 2011 Mesoscale Discussions in West Virginia, 2011 Every 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.