Alert archive / Montana / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 12, NWS Great Falls, MT

May 20, 20204 counties in Montana

NWS Great Falls, MT issued this severe thunderstorm warning at May 20, 2020, 2:00 AM MDT for 4 counties in Montana. It was in force for 45 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, 2020, 2:00 AM MDT (08:00 UTC)
Expired
May 20, 2020, 2:45 AM MDT
In force
45 min
Issued by
NWS Great Falls, MT
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Cascade County, MT, Chouteau County, MT, Pondera County, MT, Teton County, MT

The radar

The Great Falls radar (KTFX), 42 km from the middle of the area, began a volume at 08:00 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 nearest sounding before it

Great_falls, MT (KTFX), launched 00:00Z, 8.0 hours before the alert went out and 82 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, Great_falls, MT at 00:00Z on 2020-05-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Great_falls, MT at 00:00Z on 2020-05-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 26 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1347 m above ground
0-6 km bulk shear
80 kt
0-1 km storm-relative helicity
26 m²/s²
0-3 km storm-relative helicity
386 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 Great Falls, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at May 20, 12:03 AM MDT, 1 hour 57 minutes earlier.

Area forecast discussion, May 20, 12:03 AM MDT, 1 hour 57 minutes before
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In the hours before

Special weather statement, May 20, 12:59 AM MDT, 1 hour 1 minute before
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Special weather statement, May 20, 1:17 AM MDT, 43 minutes before
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<body>
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    <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.
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      <p id="message2">
        Please try again in a few minutes.
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      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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Special weather statement, May 20, 1:25 AM MDT, 35 minutes before
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<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.
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      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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Special weather statement, May 20, 1:41 AM MDT, 19 minutes before
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<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.
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      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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Special weather statement, May 20, 1:44 AM MDT, 16 minutes before
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<head>
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</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>
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Local storm report, May 20, 1:59 AM MDT, 1 minute before
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</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>

The office that day

Everything else NWS Great Falls, MT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 19, 6:02 PM MDTSpecial Weather StatementTFXCascade28 min
May 19, 6:14 PM MDTSpecial Weather StatementTFXMeagher31 min
May 19, 6:30 PM MDTSpecial Weather StatementTFX30 min
May 19, 6:47 PM MDTSpecial Weather StatementTFXWheatland43 min
May 19, 7:01 PM MDTSpecial Weather StatementTFX44 min
May 19, 7:25 PM MDTSpecial Weather StatementTFXWheatland50 min
May 19, 7:43 PM MDTSpecial Weather StatementTFX32 min
May 19, 7:54 PM MDTSpecial Weather StatementTFXFergus36 min
May 19, 8:04 PM MDTSpecial Weather StatementTFX41 min
May 19, 8:08 PM MDTSpecial Weather StatementTFXFergus52 min
May 19, 8:19 PM MDTSevere Thunderstorm WarningTFXFergus26 min
May 19, 8:47 PM MDTSevere Thunderstorm WarningTFXFergus28 min
May 19, 8:53 PM MDTSpecial Weather StatementTFXLewis and Clark37 min
May 19, 8:59 PM MDTSevere Thunderstorm WarningTFXFergus61 min
May 19, 9:03 PM MDTSpecial Weather StatementTFXSilver Bow27 min
May 19, 9:06 PM MDTSpecial Weather StatementTFXMeagher24 min
May 19, 9:25 PM MDTSevere Thunderstorm WarningTFXFergus35 min
May 19, 9:52 PM MDTSpecial Weather StatementTFXPetroleum23 min
May 19, 9:54 PM MDTSpecial Weather StatementTFXMeagher36 min
May 19, 9:56 PM MDTSpecial Weather StatementTFXLewis and Clark34 min
May 19, 10:29 PM MDTSpecial Weather StatementTFXDeer Lodge46 min
May 19, 10:31 PM MDTSpecial Weather StatementTFXLewis and Clark29 min
May 19, 11:26 PM MDTSpecial Weather StatementTFXJefferson34 min
May 19, 11:28 PM MDTSpecial Weather StatementTFXSilver Bow32 min
May 19, 11:53 PM MDTSpecial Weather StatementTFXBroadwater37 min
May 20, 12:20 AM MDTSpecial Weather StatementTFXLewis and Clark25 min
May 20, 12:41 AM MDTSpecial Weather StatementTFXLewis and Clark34 min
May 20, 12:59 AM MDTSpecial Weather StatementTFXLewis and Clark31 min
May 20, 1:17 AM MDTSpecial Weather StatementTFXLewis and Clark28 min
May 20, 1:25 AM MDTSpecial Weather StatementTFXCascade35 min
May 20, 1:41 AM MDTSpecial Weather StatementTFXLewis and Clark34 min
May 20, 1:44 AM MDTSpecial Weather StatementTFXCascade31 min
May 20, 2:06 AM MDTSpecial Weather StatementTFXPetroleum24 min
May 20, 2:11 AM MDTSpecial Weather StatementTFXLewis and Clark34 min
May 20, 2:40 AM MDTSpecial Weather StatementTFXLiberty35 min
May 20, 2:44 AM MDTSpecial Weather StatementTFXTeton46 min
May 20, 3:24 AM MDTSpecial Weather StatementTFXPondera36 min
May 20, 3:50 AM MDTHigh Wind WatchTFX18 hr
May 20, 4:33 AM MDTSpecial Weather StatementTFXLewis and Clark42 min
May 20, 5:09 AM MDTSpecial Weather StatementTFXLewis and Clark51 min
May 20, 7:48 AM MDTSpecial Weather StatementTFXPondera42 min
May 20, 11:42 AM MDTSpecial Weather StatementTFXLiberty48 min
May 20, 12:35 PM MDTSpecial Weather StatementTFXLiberty25 min
May 20, 1:53 PM MDTSpecial Weather StatementTFXJudith Basin22 min
May 20, 2:30 PM MDTSpecial Weather StatementTFXChouteau45 min
May 20, 2:57 PM MDTSpecial Weather StatementTFXChouteau48 min
May 20, 4:02 PM MDTSpecial Weather StatementTFXFergus43 min
May 20, 4:40 PM MDTSpecial Weather StatementTFXFergus50 min
May 20, 5:00 PM MDTSpecial Weather StatementTFXFergus30 min
May 20, 5:26 PM MDTSpecial Weather StatementTFXFergus34 min

Nearby

Severe Thunderstorm Warnings in Montana, 2020Every severe thunderstorm warning in 2020

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.