Alert archive / Washington / River Flood Warnings in 2020

River Flood Warning 74, NWS Seattle, WA

December 21, 2020Snohomish County, Washington

NWS Seattle, WA issued this river flood warning at Dec 21, 2020, 7:36 PM PST for Snohomish County, Washington. It took effect at Dec 21, 2020, 8:11 PM PST. It was in force for 13 hr.

The area

The counties it named.

The facts

Issued: Dec 21, 2020, 7:36 PM PST (03:36 UTC)
In effect from: Dec 21, 2020, 8:11 PM PST
Expired: Dec 22, 2020, 9:17 AM PST
In force: 13 hr
Issued by: NWS Seattle, WA
Area: Storm-based polygon
Flood severity: Minor

County Snohomish County, WA

The radar

The Seattle radar (KATX), 60 km from the middle of the area, began a volume at 03:40 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 river

Written for the forecast point Stillaguamish River at Arlington (ARLW1).

Action stage: 12.5 ft
Minor stage: 14 ft
Moderate stage: 17.5 ft
Major stage: 19 ft

This gauge today: stage, forecast and historic crests

Stage from the USGS instantaneous record for site 12167400, one reading an hour, from a day before the product to a day after it ended. Flood stages are today's.

What forecasters said that day

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

NWS Seattle, WA wrote its last area forecast discussion before this river flood warning went out at Dec 21, 3:54 PM PST, 3 hours 42 minutes earlier.

Area forecast discussion, Dec 21, 3:54 PM PST, 3 hours 42 minutes before

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In the hours before

Special weather statement, Dec 21, 3:48 PM PST, 3 hours 48 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>

The office that day

Everything else NWS Seattle, WA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 21, 4:19 PM PST	Flood Watch	SEW	Snohomish	4 hr
Dec 21, 6:57 PM PST	River Flood Warning	SEW	Snohomish	13 hr
Dec 22, 2:23 AM PST	Small Craft Advisory	SEW		22 hr

Nearby

River Flood Warnings in Washington, 2020 Every river flood 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; radar from the NEXRAD Level II archive; the gauge from the NWS water service and the USGS.