Alert archive / Iowa / Severe Thunderstorm Warnings in 2024

Severe Thunderstorm Warning 77, NWS Des Moines, IA

May 20, 20247 counties in Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 20, 2024, 1:36 AM CDT for 7 counties in Iowa. It was in force for 54 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 20, 2024, 1:36 AM CDT (06:36 UTC)
Expired: May 20, 2024, 2:30 AM CDT
In force: 54 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

Counties Appanoose County, IA, Clarke County, IA, Lucas County, IA, Marion County, IA, Monroe County, IA, Warren County, IA, Wayne County, IA

The radar

The Des Moines radar (KDMX), 86 km from the middle of the area, began a volume at 06:40 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 19, 6:25 PM CDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 6.6 hours before the alert went out and 240 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: 65 J/kg
Mixed-layer CIN: -185 J/kg
Mixed-layer LCL: 2316 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 73 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Des Moines, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at May 19, 11:44 PM CDT, 1 hour 52 minutes earlier.

Area forecast discussion, May 19, 11:44 PM CDT, 1 hour 52 minutes before

<!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>

Hazardous weather outlook, May 19, 4:58 AM CDT, 20 hours 38 minutes before

Hazardous Weather Outlook
National Weather Service Des Moines IA
458 AM CDT Sun May 19 2024

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-201000-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun-
Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-Greene-
Boone-Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-Jasper-
Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union-
Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne-
Appanoose-Davis-
458 AM CDT Sun May 19 2024

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

Thunderstorms will track from west to east through the area today
and into tonight. A few storms this afternoon and evening may be
strong to severe, especially over southern Iowa. Strong winds,
hail and locally heavy rainfall will be the primary concerns, but
a tornado can't be ruled out.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Additional storms are expected on Monday, with the potential for
more strong to severe storms in the afternoon and evening hours.
Main threats will again be strong winds, hail and locally heavy
rainfall, with the potential for a tornado or two as well.

The greatest severe risk through the period will fall on Tuesday
as a larger scale system passes through the area. All hazards
may be possible, including damaging winds, large hail, heavy
rainfall and tornadoes. More details on this system will be
provided in the coming days.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will be needed for any storms this afternoon
through Tuesday.

Dodson

In the hours before

Local storm report, May 19, 8:54 PM CDT, 4 hours 42 minutes before

<!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>

Local storm report, May 19, 8:57 PM CDT, 4 hours 39 minutes before

<!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>

Special weather statement, May 19, 10:40 PM CDT, 2 hours 56 minutes before

<!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>

Local storm report, May 19, 11:58 PM CDT, 1 hour 38 minutes before

<!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>

Special weather statement, May 20, 1:26 AM CDT, 10 minutes before

Special Weather Statement
National Weather Service Des Moines IA
126 AM CDT Mon May 20 2024

IAZ060-061-073>075-083>086-095>097-200730-
Wapello IA-Appanoose IA-Marion IA-Jasper IA-Clarke IA-Lucas IA-
Polk IA-Wayne IA-Davis IA-Mahaska IA-Monroe IA-Warren IA-
126 AM CDT Mon May 20 2024

...STRONG THUNDERSTORMS WILL IMPACT LUCAS...MONROE...SOUTHEASTERN
POLK...WESTERN DAVIS...MARION...WESTERN WAPELLO...EASTERN WAYNE...
WESTERN MAHASKA...APPANOOSE...SOUTHERN JASPER...NORTHEASTERN CLARKE
AND EASTERN WARREN COUNTIES THROUGH 230 AM CDT...

At 125 AM CDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line extending from 12 miles west of Chariton
to 9 miles east of Corydon to near Novinger. Movement was north at 35
mph.

HAZARD...Wind gusts up to 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Indianola, Oskaloosa, Pella, Knoxville, Centerville, Chariton, Albia,
Bloomfield, Corydon, Carlisle, Monroe, Pleasantville, Melcher-Dallas,
Eddyville, Lake Sundown, Rathbun Lake, Knoxville Raceway, Lake Red
Rock, Sully, and Milo.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 200 AM CDT for
south central Iowa.

&&

LAT...LON 4067 9322 4104 9369 4159 9345 4158 9280
      4131 9258 4060 9238 4058 9315
TIME...MOT...LOC 0625Z 197DEG 32KT 4106 9354 4075 9314 4021 9274

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

Dodson

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 19, 7:14 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk	42 min
May 19, 7:30 PM CDT	Special Weather Statement	DMX	Cass	30 min
May 19, 7:58 PM CDT	Severe Thunderstorm Warning	DMX	Adair, Adams, Audubon, Cass, Guthrie, Madison and 3 more	47 min
May 19, 8:42 PM CDT	Severe Thunderstorm Warning	DMX	Adair, Dallas, Guthrie, Madison	48 min
May 19, 8:53 PM CDT	Severe Thunderstorm Warning	DMX	Adams, Ringgold, Taylor, Union	52 min
May 19, 10:40 PM CDT	Special Weather Statement	DMX	Adair, Adams, Cass, Guthrie	50 min
May 20, 12:14 AM CDT	Severe Thunderstorm Warning	DMX	Clarke, Decatur, Ringgold, Union	27 min
May 20, 1:26 AM CDT	Special Weather Statement	DMX	Appanoose, Lucas, Mahaska, Marion, Monroe	64 min
May 20, 1:50 PM CDT	Flood Watch	DMX	Adair, Adams, Audubon, Black Hawk, Boone, Bremer and 37 more	29 hr

Nearby

Severe Thunderstorm Warnings in Iowa, 2024 Every severe thunderstorm warning 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.