Alert archive / Missouri / Severe Thunderstorm Warnings in 2026

Severe Thunderstorm Warning 171, NWS St. Louis, MO

June 11, 2026Knox County, Lewis County, Missouri

NWS St. Louis, MO issued this severe thunderstorm warning at Jun 11, 2026, 10:09 AM CDT for Knox County, Lewis County, Missouri. It was in force for 51 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: Jun 11, 2026, 10:09 AM CDT (15:09 UTC)
Expired: Jun 11, 2026, 11:00 AM CDT
In force: 51 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Hail: 1.25 in
Wind: 60.0 mph

Counties Knox County, MO, Lewis County, MO

The radar

The St Louis radar (KLSX), 190 km from the middle of the area, began a volume at 15:09 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 watch it was issued in

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

Issued	Product	Office	Lasted
Jun 11, 7:31 AM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 3.2 hours before the alert went out and 207 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: 11 J/kg
Mixed-layer CIN: -285 J/kg
Mixed-layer LCL: 1008 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 54 m²/s²
0-3 km storm-relative helicity: -15 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

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 St. Louis, MO wrote its last area forecast discussion before this severe thunderstorm warning went out at Jun 11, 6:48 AM CDT, 3 hours 21 minutes earlier.

Area forecast discussion, Jun 11, 6:48 AM CDT, 3 hours 21 minutes before

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In the hours before

Local storm report, Jun 11, 8:04 AM CDT, 2 hours 5 minutes before

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  <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>
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      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
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      <p id="message2">
        Please try again in a few minutes.
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        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 10, 7:20 PM CDT	Severe Thunderstorm Warning	LSX	Lewis	55 min
Jun 10, 8:19 PM CDT	Flash Flood Warning	LSX	Knox, Lewis	5 hr
Jun 10, 10:55 PM CDT	River Flood Warning	LSX	Lewis	71 hr
Jun 10, 10:55 PM CDT	River Flood Warning	LSX	Monroe	38 hr
Jun 10, 10:55 PM CDT	River Flood Warning	LSX	Lewis	3 days
Jun 10, 11:05 PM CDT	Flash Flood Warning	LSX	Knox, Lewis, Marion, Shelby	3 hr
Jun 11, 1:22 AM CDT	River Flood Warning	LSX	Marion	52 hr
Jun 11, 2:01 AM CDT	River Flood Warning	LSX	Marion	4 days
Jun 11, 11:50 AM CDT	Flood Watch	LSX	Knox, Lewis, Marion, Shelby	7 hr
Jun 11, 3:29 PM CDT	Severe Thunderstorm Warning	LSX	Knox	61 min
Jun 11, 3:44 PM CDT	Flash Flood Warning	LSX	Knox	3 hr
Jun 11, 4:02 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Shelby	58 min
Jun 11, 4:41 PM CDT	Flash Flood Warning	LSX	Shelby	3 hr
Jun 11, 4:48 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Lewis, Marion, Shelby	57 min
Jun 11, 4:58 PM CDT	Severe Thunderstorm Warning	LSX	Shelby	47 min
Jun 11, 5:15 PM CDT	Flash Flood Warning	LSX	Lewis, Marion	108 min
Jun 11, 5:24 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Boone, Monroe	66 min
Jun 11, 5:34 PM CDT	Severe Thunderstorm Warning	LSX	Marion, Monroe, Ralls, Shelby	43 min
Jun 11, 6:49 PM CDT	Severe Thunderstorm Warning	LSX	Boone, Callaway	41 min
Jun 10, 7:57 PM CDT	Severe Thunderstorm Warning	LSX	Adams	48 min

Nearby

Severe Thunderstorm Warnings in Missouri, 2026 Every severe thunderstorm warning in 2026

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.