Alert archive / Illinois / Mesoscale Discussions in 2003

Mesoscale Discussion 1879

July 18, 200322 counties in Illinois; 18 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Jul 18, 2003, 9:06 AM CDT for 22 counties in Illinois; 18 counties in Missouri. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued
Jul 18, 2003, 9:06 AM CDT (14:06 UTC)
Expired
Jul 18, 2003, 10:30 AM CDT
In force
84 min
Issued by
the Storm Prediction Center
All 40 counties

Alexander County, IL, Bond County, IL, Calhoun County, IL, Clinton County, IL, Franklin County, IL, Greene County, IL, Jackson County, IL, Jersey County, IL, Johnson County, IL, Macoupin County, IL, Madison County, IL, Monroe County, IL, Morgan County, IL, Perry County, IL, Pike County, IL, Pulaski County, IL, Randolph County, IL, Saint Clair County, IL, Scott County, IL, Union County, IL, Washington County, IL, Williamson County, IL, Bollinger County, MO, Cape Girardeau County, MO, City of Saint Louis, MO, Franklin County, MO, Jefferson County, MO, Lincoln County, MO, Marion County, MO, Montgomery County, MO, Perry County, MO, Pike County, MO, Ralls County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Scott County, MO, Shelby County, MO, Warren County, MO

The radar

The St Louis radar (KLSX), 36 km from the middle of the area, began a volume at 14:09 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.

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 2.1 hours before the alert went out and 214 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-pSkew-T log-p diagram, Lincoln, IL at 12:00Z on 2003-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 315 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 12:00Z on 2003-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 183 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
315 J/kg
Mixed-layer CIN
-200 J/kg
Mixed-layer LCL
874 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
183 m²/s²
0-3 km storm-relative helicity
243 m²/s²
Significant tornado parameter
0.0
Supercell composite
6.2

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.

IssuedProductOfficeCountiesLasted
Jul 17, 9:40 PM CDTSevere Thunderstorm WatchSPCBureau, Champaign, DeWitt, Ford, Grundy, Henry and 13 more5 hr
Jul 17, 11:41 PM CDTMesoscale DiscussionSPCBureau, Champaign, Ford, Grundy, Henry, Iroquois and 12 more94 min
Jul 18, 2:01 AM CDTMesoscale DiscussionSPCChampaign, Clark, Coles, Cumberland, DeWitt, Douglas and 13 more59 min
Jul 18, 2:26 AM CDTMesoscale DiscussionSPCHenderson, Knox, Mercer, Rock Island, Warren3 hr
Jul 18, 4:30 AM CDTSevere Thunderstorm WatchSPCAdams, Bond, Brown, Calhoun, Cass, Christian and 38 more6 hr
Jul 18, 6:15 AM CDTMesoscale DiscussionSPCAdams, Alexander, Bond, Brown, Calhoun, Clinton and 18 more60 min
Jul 18, 6:50 AM CDTSevere Thunderstorm WatchSPCAlexander, Franklin, Jackson, Johnson, Monroe, Perry and 6 more5 hr
Jul 18, 9:55 AM CDTSevere Thunderstorm WatchSPCAlexander, Clinton, Franklin, Gallatin, Hamilton, Hardin and 15 more5 hr
Jul 18, 3:23 PM CDTMesoscale DiscussionSPCAdams, Calhoun, Jersey, Monroe, Pike, Randolph97 min
Jul 18, 3:45 PM CDTSevere Thunderstorm WatchSPCCalhoun, Greene, Jersey, Monroe5 hr
Jul 18, 12:45 PM CDTMesoscale DiscussionSPCButler, Dunklin, Mississippi, New Madrid, Pemiscot, Stoddard60 min

Nearby

Mesoscale Discussions in Illinois, 2003Mesoscale Discussions in Missouri, 2003Every mesoscale discussion in 2003

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.