Alert archive / Illinois / Mesoscale Discussions in 2024

Mesoscale Discussion 2017

August 27, 20245 states

The Storm Prediction Center issued this mesoscale discussion at Aug 27, 2024, 4:47 PM CDT for 5 states. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued
Aug 27, 2024, 4:47 PM CDT (21:47 UTC)
Expired
Aug 27, 2024, 6:15 PM CDT
In force
88 min
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch possible
Chance of a watch
60%
All 38 counties

Des Moines County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Grundy County, IL, Henderson County, IL, Henry County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Marshall County, IL, McHenry County, IL, Mercer County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Warren County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Woodford County, IL, Lake County, IN, LaPorte County, IN, Porter County, IN, Starke County, IN, Berrien County, MI, Kenosha County, WI, Walworth County, WI

The radar

The Chicago radar (KLOT), 97 km from the middle of the area, began a volume at 21:49 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

Davenport, (KDVN), launched 12:00Z, 9.8 hours before the alert went out and 106 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, Davenport, at 12:00Z on 2024-08-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3530 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, Davenport, at 12:00Z on 2024-08-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -4 square meters per square second.1939Sfc1 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
3530 J/kg
Mixed-layer CIN
-163 J/kg
Mixed-layer LCL
1209 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
-4 m²/s²
0-3 km storm-relative helicity
25 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

<!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
Aug 27, 11:25 AM CDTMesoscale DiscussionSPCBoone, Cook, DeKalb, DuPage, Kane, Kendall and 6 more3 hr
Aug 27, 12:04 PM CDTSevere Thunderstorm WatchSPCBoone, Lake, McHenry, Winnebago2 hr
Aug 27, 5:09 PM CDTSevere Thunderstorm WatchSPCBoone, Cook, DeKalb, DuPage, Ford, Grundy and 12 more6 hr
Aug 27, 5:16 PM CDTMesoscale DiscussionSPCAdams, Brown, Calhoun, Greene, Jersey, Pike and 1 more119 min
Aug 27, 6:24 PM CDTMesoscale DiscussionSPCCook, DuPage, Kane, Lake, McHenry, Will96 min
Aug 27, 3:56 PM CDTMesoscale DiscussionSPCAdams, Allen, DeKalb, Elkhart, Fulton, Huntington and 11 more2 hr
Aug 26, 9:28 PM CDTMesoscale DiscussionSPCBuena Vista, Cherokee, Clay, Dickinson, Emmet, Lyon and 6 more92 min
Aug 26, 10:55 PM CDTSevere Thunderstorm WatchSPCCherokee, Clay, Dickinson, Lyon, O'Brien, Osceola and 2 more6 hr
Aug 27, 12:41 AM CDTMesoscale DiscussionSPCClay, Dickinson, Lyon, O'Brien, Osceola, Sioux94 min
Aug 27, 3:46 AM CDTMesoscale DiscussionSPCBuena Vista, Butler, Calhoun, Cerro Gordo, Chickasaw, Clay and 15 more59 min
Aug 26, 11:11 PM CDTMesoscale DiscussionSPCDickinson, Iron, Menominee64 min
Aug 27, 12:48 PM CDTSevere Thunderstorm WatchSPCAllegan, Arenac, Barry, Benzie, Calhoun, Clare and 29 more5 hr
Aug 27, 2:46 PM CDTMesoscale DiscussionSPCArenac, Barry, Bay, Calhoun, Clinton, Eaton and 22 more119 min
Aug 27, 2:52 PM CDTSevere Thunderstorm WatchSPCBay, Genesee, Huron, Lapeer, Lenawee, Livingston and 11 more3 hr
Aug 26, 7:51 PM CDTMesoscale DiscussionSPCAdams, Brown, Calumet, Chippewa, Clark, Eau Claire and 19 more84 min
Aug 26, 8:41 PM CDTSevere Thunderstorm WatchSPCAdams, Ashland, Bayfield, Brown, Buffalo, Calumet and 34 more7 hr
Aug 26, 9:19 PM CDTMesoscale DiscussionSPCBarron, Buffalo, Burnett, Chippewa, Clark, Dunn and 19 more86 min
Aug 27, 5:57 AM CDTMesoscale DiscussionSPCBarron, Chippewa, Dunn, Eau Claire, Pierce, Rusk and 1 more93 min

Nearby

Mesoscale Discussions in Illinois, 2024Mesoscale Discussions in Indiana, 2024Mesoscale Discussions in Wisconsin, 2024Every mesoscale discussion in 2024

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.