Alert archive / Colorado / Severe Thunderstorm Warnings in 2023

Severe Thunderstorm Warning 355, NWS Denver/Boulder, CO

July 31, 2023Washington County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 31, 2023, 10:51 PM MDT for Washington County, Colorado. It was in force for 24 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: Jul 31, 2023, 10:51 PM MDT (04:51 UTC)
Expired: Jul 31, 2023, 11:15 PM MDT
In force: 24 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

County Washington County, CO

The radar

The Denver radar (KFTG), 117 km from the middle of the area, began a volume at 04:53 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.

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 Denver/Boulder, CO wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 31, 9:27 PM MDT, 1 hour 24 minutes earlier.

Area forecast discussion, Jul 31, 9:27 PM MDT, 1 hour 24 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, Jul 31, 11:03 AM MDT, 11 hours 48 minutes before

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1103 AM MDT Mon Jul 31 2023

COZ030>051-011715-
Jackson County Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Grand and Summit Counties Below 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet-
Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet-
Central and Southeast Park County-
Larimer County Below 6000 Feet/Northwest Weld County-
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
Northeast Weld County-Central and South Weld County-Morgan County-
Central and East Adams and Arapahoe Counties-
North and Northeast Elbert County Below 6000 Feet/North Lincoln
County-
Southeast Elbert County Below 6000 Feet/South Lincoln County-
Logan County-Washington County-Sedgwick County-Phillips County-
1103 AM MDT Mon Jul 31 2023

...Flood Watch for the I-25 Corridor, adjacent plains, and portions
of the northern mountains and foothills until midnight tonight...

This hazardous weather outlook is for northeast and north central
Colorado.

.DAY ONE...Today and Tonight

Widespread showers and thunderstorms will develop across the high
country early this afternoon, then spread over the I-25 corridor
and plains this afternoon and evening. Heavy rain and gusty winds
will be possible with stronger storms. Flash flooding will be
possible across the burn areas, I-25 corridor, and plains through
the early overnight hours.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The flash flood threat will increase for all areas Tuesday and
continue into Wednesday. Storms that develop will be capable of
producing very heavy rain and flash flooding. This includes not
only recent burn areas, but also urban areas, small creeks and
streams, and low lying areas outside of burn scars.

Never drive through flooded roads or water of unknown depth. Avoid
recent burn areas if possible, have multiple ways to receive
warnings, and be ready to take action and move to higher ground if
a warning is issued.

The active weather pattern is slated to continue into the weekend,
although some decrease in storm coverage and intensity is
expected by Thursday and Friday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today and tonight. However,
any reports of heavy rainfall, flooding, hail, and strong winds
will be appreciated.

In the hours before

Special weather statement, Jul 31, 9:34 PM MDT, 1 hour 17 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, Jul 31, 9:49 PM MDT, 1 hour 2 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, Jul 31, 9:52 PM MDT, 59 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, Jul 31, 9:55 PM MDT, 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, Jul 31, 10:19 PM MDT, 32 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, Jul 31, 10:49 PM MDT, 2 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 Denver/Boulder, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 31, 6:09 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Weld	36 min
Jul 31, 6:35 PM MDT	Areal Flood Advisory	BOU	Douglas	2 hr
Jul 31, 6:38 PM MDT	Severe Thunderstorm Warning	BOU	Boulder, Jefferson	37 min
Jul 31, 6:40 PM MDT	Severe Thunderstorm Warning	BOU	Larimer, Weld	50 min
Jul 31, 6:46 PM MDT	Special Weather Statement	BOU	Douglas	44 min
Jul 31, 7:10 PM MDT	Flash Flood Warning	BOU	Douglas	110 min
Jul 31, 7:23 PM MDT	Special Weather Statement	BOU	Arapahoe	52 min
Jul 31, 7:30 PM MDT	Severe Thunderstorm Warning	BOU	Larimer, Weld	45 min
Jul 31, 7:37 PM MDT	Flash Flood Warning	BOU	Larimer	3 hr
Jul 31, 7:52 PM MDT	Severe Thunderstorm Warning	BOU	Elbert	38 min
Jul 31, 8:12 PM MDT	Flash Flood Warning	BOU	Larimer	3 hr
Jul 31, 8:14 PM MDT	Flash Flood Warning	BOU	Larimer	3 hr
Jul 31, 8:38 PM MDT	Special Weather Statement	BOU	Adams, Arapahoe	52 min
Jul 31, 9:26 PM MDT	River Flood Warning	BOU	Douglas	6 hr
Jul 31, 9:34 PM MDT	Special Weather Statement	BOU	Elbert	26 min
Jul 31, 9:49 PM MDT	Special Weather Statement	BOU	Elbert	26 min
Jul 31, 10:49 PM MDT	Special Weather Statement	BOU	Washington	41 min
Aug 1, 2:17 PM MDT	Special Weather Statement	BOU	Jefferson	43 min
Aug 1, 2:24 PM MDT	Severe Thunderstorm Warning	BOU	Jefferson	36 min
Aug 1, 2:58 PM MDT	Severe Thunderstorm Warning	BOU	Douglas, Jefferson	32 min
Aug 1, 3:23 PM MDT	Flash Flood Warning	BOU	Jefferson	3 hr
Aug 1, 3:27 PM MDT	Severe Thunderstorm Warning	BOU	Douglas, Jefferson	19 min
Aug 1, 3:58 PM MDT	Special Weather Statement	BOU	Washington	32 min
Aug 1, 4:06 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe, Washington	24 min
Aug 1, 4:10 PM MDT	Special Weather Statement	BOU	Denver	35 min
Aug 1, 4:19 PM MDT	Severe Thunderstorm Warning	BOU	Larimer, Weld	26 min
Aug 1, 4:28 PM MDT	Severe Thunderstorm Warning Considerable damage threat	BOU	Arapahoe, Washington	47 min
Aug 1, 5:05 PM MDT	Special Weather Statement	BOU	Boulder	25 min
Aug 1, 5:13 PM MDT	Flash Flood Warning	BOU	Boulder	3 hr
Aug 1, 5:15 PM MDT	Severe Thunderstorm Warning	BOU	Adams	30 min
Aug 1, 5:37 PM MDT	Areal Flood Advisory	BOU	Washington	3 hr
Aug 1, 5:40 PM MDT	Special Weather Statement	BOU	Broomfield	50 min
Aug 1, 5:43 PM MDT	Severe Thunderstorm Warning	BOU	Weld	32 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2023 Every severe thunderstorm warning in 2023

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.