Alert archive / Iowa / Mesoscale Discussions in 2004
Mesoscale Discussion 778
The Storm Prediction Center issued this mesoscale discussion at May 20, 2004, 4:54 PM CDT for 39 counties in Iowa; Worth County, Missouri. It was in force for 96 min.
The area
The outline as issued.
The facts
- Issued
- May 20, 2004, 4:54 PM CDT (21:54 UTC)
- Expired
- May 20, 2004, 6:30 PM CDT
- In force
- 96 min
- Issued by
- the Storm Prediction Center
All 40 counties
Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Boone County, IA, Cass County, IA, Clarke County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Monroe County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Ringgold County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Worth County, MO
The radar
The Des Moines radar (KDMX), 77 km from the middle of the area, began a volume at 21:53 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, 9.9 hours before the alert went out and 237 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.
- Mixed-layer CAPE
- 1924 J/kg
- Mixed-layer CIN
- -45 J/kg
- Mixed-layer LCL
- 689 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 209 m²/s²
- 0-3 km storm-relative helicity
- 197 m²/s²
- Significant tornado parameter
- 1.6
- Supercell composite
- 9.4
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 19, 7:12 PM CDT | Mesoscale Discussion | SPC | Audubon, Calhoun, Carroll, Emmet, Floyd, Franklin and 15 more | 2 hr |
| May 20, 11:31 AM CDT | Mesoscale Discussion | SPC | Adair, Benton, Black Hawk, Boone, Buchanan, Cedar and 37 more | 2 hr |
| May 20, 3:35 PM CDT | Severe Thunderstorm Watch | SPC | Benton, Black Hawk, Buchanan, Cedar, Clinton, Delaware and 15 more | 6 hr |
| May 20, 5:00 PM CDT | Tornado Watch | SPC | Adair, Adams, Appanoose, Audubon, Cass, Clarke and 23 more | 5 hr |
Nearby
Mesoscale Discussions in Iowa, 2004Mesoscale Discussions in Missouri, 2004Every mesoscale discussion in 2004
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.