Alert archive / Maine / Mesoscale Discussions in 2015

Mesoscale Discussion 820

May 28, 20156 states

The Storm Prediction Center issued this mesoscale discussion at May 28, 2015, 11:30 AM EDT for 6 states. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued: May 28, 2015, 11:30 AM EDT (15:30 UTC)
Expired: May 28, 2015, 12:30 PM EDT
In force: 60 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 54 counties

Berkshire County, MA, Essex County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Worcester County, MA, Androscoggin County, ME, Aroostook County, ME, Cumberland County, ME, Franklin County, ME, Hancock County, ME, Kennebec County, ME, Lincoln County, ME, Oxford County, ME, Penobscot County, ME, Piscataquis County, ME, Sagadahoc County, ME, Somerset County, ME, Waldo County, ME, York County, ME, Belknap County, NH, Carroll County, NH, Cheshire County, NH, Coos County, NH, Grafton County, NH, Hillsborough County, NH, Merrimack County, NH, Rockingham County, NH, Strafford County, NH, Sullivan County, NH, Bergen County, NJ, Passaic County, NJ, Albany County, NY, Columbia County, NY, Dutchess County, NY, Greene County, NY, Orange County, NY, Putnam County, NY, Rensselaer County, NY, Rockland County, NY, Schenectady County, NY, Sullivan County, NY, Ulster County, NY, Washington County, NY, Westchester County, NY, Bennington County, VT, Caledonia County, VT, Essex County, VT, Orange County, VT, Rutland County, VT, Washington County, VT, Windham County, VT, Windsor County, VT

The radar

The Portland,ME radar (KGYX), 59 km from the middle of the area, began a volume at 15:30 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 233May 28, 11:50 AM EDT

The nearest sounding before it

Gray, ME (KGYX), launched 12:00Z, 3.5 hours before the alert went out and 59 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: 60 J/kg
Mixed-layer CIN: -149 J/kg
Mixed-layer LCL: 1028 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 27 m²/s²
0-3 km storm-relative helicity: 74 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
May 28, 11:16 AM EDT	Mesoscale Discussion	SPC		89 min
May 28, 11:54 AM EDT	Severe Thunderstorm Watch	SPC	Greater Bridgeport Planning Region, Capitol Planning Region, Northwest Hills Planning Region, Lower Connecticut River Valley Planning Region, Naugatuck Valley Planning Region, Southeastern Connecticut Planning Region and 1 more	7 hr
May 28, 3:08 PM EDT	Mesoscale Discussion	SPC		97 min
May 28, 4:26 PM EDT	Mesoscale Discussion	SPC		64 min

Nearby

Mesoscale Discussions in Maine, 2015 Mesoscale Discussions in New York, 2015 Mesoscale Discussions in New Hampshire, 2015 Every mesoscale discussion in 2015

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.