Alert archive / Illinois / Mesoscale Discussions in 2011

Mesoscale Discussion 2107

September 3, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2011, 12:24 PM CDT for 4 states. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: Sep 3, 2011, 12:24 PM CDT (17:24 UTC)
Expired: Sep 3, 2011, 1:30 PM CDT
In force: 66 min
Issued by: the Storm Prediction Center

All 39 counties

Bureau County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Livingston County, IL, Marshall County, IL, McHenry County, IL, Putnam County, IL, Stark County, IL, Will County, IL, Woodford County, IL, Elkhart County, IN, Fulton County, IN, Jasper County, IN, Lake County, IN, LaPorte County, IN, Marshall County, IN, Newton County, IN, Porter County, IN, Pulaski County, IN, Saint Joseph County, IN, Starke County, IN, White County, IN, Allegan County, MI, Berrien County, MI, Cass County, MI, Kalamazoo County, MI, Saint Joseph County, MI, Van Buren County, MI, Kenosha County, WI, Racine County, WI

The radar

The Chicago radar (KLOT), 33 km from the middle of the area, began a volume at 17:24 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 829Sep 3, 3:05 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 5.4 hours before the alert went out and 174 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: 1443 J/kg
Mixed-layer CIN: -94 J/kg
Mixed-layer LCL: 1535 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: -21 m²/s²
0-3 km storm-relative helicity: 11 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

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
Sep 2, 11:56 PM CDT	Mesoscale Discussion	SPC	Carroll, Jo Daviess, Ogle, Stephenson, Whiteside, Winnebago	94 min
Sep 3, 12:48 AM CDT	Severe Thunderstorm Watch	SPC	Boone, Jo Daviess, McHenry, Stephenson, Winnebago	6 hr
Sep 3, 3:05 PM CDT	Severe Thunderstorm Watch	SPC	Bureau, Cook, DuPage, Ford, Fulton, Grundy and 23 more	7 hr
Sep 3, 5:02 PM CDT	Mesoscale Discussion	SPC	Bureau, Cook, DuPage, Ford, Fulton, Grundy and 23 more	58 min
Sep 3, 5:53 AM CDT	Mesoscale Discussion	SPC	Clinton, Genesee, Gratiot, Ionia, Isabella, Kent and 5 more	97 min
Sep 3, 6:22 AM CDT	Severe Thunderstorm Watch	SPC	Allegan, Barry, Bay, Clinton, Eaton, Genesee and 19 more	5 hr
Sep 3, 9:45 AM CDT	Mesoscale Discussion	SPC	Arenac, Bay, Huron, Sanilac, Tuscola	60 min
Sep 3, 3:40 AM CDT	Mesoscale Discussion	SPC	Dane, Green, Iowa, Jefferson, Kenosha, Lafayette and 6 more	95 min

Nearby

Mesoscale Discussions in Illinois, 2011 Mesoscale Discussions in Indiana, 2011 Mesoscale Discussions in Michigan, 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.