Alert archive / California / Severe Thunderstorm Warnings in 2025

Severe Thunderstorm Warning 59, NWS Las Vegas, NV

September 18, 2025San Bernardino County, California

NWS Las Vegas, NV issued this severe thunderstorm warning at Sep 18, 2025, 8:42 PM PDT for San Bernardino County, California. It was in force for 48 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: Sep 18, 2025, 8:42 PM PDT (03:42 UTC)
Expired: Sep 18, 2025, 9:30 PM PDT
In force: 48 min
Issued by: NWS Las Vegas, NV
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County San Bernardino County, CA

The radar

The Edwards AFB radar (KEYX), 129 km from the middle of the area, began a volume at 03:43 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

Las Vegas, NV (KVEF), launched 00:00Z, 3.7 hours before the alert went out and 180 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1274 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 186 m²/s²
0-3 km storm-relative helicity: 292 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 Las Vegas, NV wrote its last area forecast discussion before this severe thunderstorm warning went out at Sep 18, 4:27 PM PDT, 4 hours 15 minutes earlier.

Area forecast discussion, Sep 18, 4:27 PM PDT, 4 hours 15 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>

In the hours before

Local storm report, Sep 18, 5:20 PM PDT, 3 hours 22 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, Sep 18, 8:16 PM PDT, 26 minutes before

Preliminary Local Storm Report
National Weather Service Las Vegas NV
816 PM PDT Thu Sep 18 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0622 PM     Rain             28 WNW Lenwood          35.05N 117.56W
09/18/2025  U0.00 Inch       San Bernardino     CA   Law Enforcement

            Roadway flooding 6 to 8 inches deep on U.S.
            395 north of Kramer Junction per California
            Highway Patrol report.

&&

SM

Local storm report, Sep 18, 8:23 PM PDT, 19 minutes before

Preliminary Local Storm Report
National Weather Service Las Vegas NV
823 PM PDT Thu Sep 18 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0549 PM     Flash Flood      6 SW Nebo Center        34.80N 117.02W
09/18/2025                   San Bernardino     CA   Dept of Highways

            Water flowing over roadway on SR-247 at mile
            marker 72.

&&

MS

The office that day

Everything else NWS Las Vegas, NV issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 19, 12:38 AM PDT	Flash Flood Warning Considerable damage threat	VEF	Nye	4 hr
Sep 19, 2:49 PM PDT	Areal Flood Advisory	VEF	Clark	3 hr
Sep 19, 4:34 PM PDT	Areal Flood Advisory	VEF	Clark	3 hr
Sep 18, 6:05 PM PDT	Areal Flood Advisory	VEF	San Bernardino	3 hr
Sep 18, 7:21 PM PDT	Areal Flood Advisory	VEF	Inyo	3 hr
Sep 18, 7:41 PM PDT	Areal Flood Advisory	VEF	San Bernardino	3 hr
Sep 18, 9:24 PM PDT	Areal Flood Advisory	VEF	San Bernardino	3 hr
Sep 18, 9:32 PM PDT	Areal Flood Advisory	VEF	Inyo	4 hr
Sep 18, 9:45 PM PDT	Areal Flood Advisory	VEF	San Bernardino	3 hr
Sep 18, 10:38 PM PDT	Areal Flood Advisory	VEF	Inyo, San Bernardino	3 hr
Sep 18, 10:48 PM PDT	Areal Flood Advisory	VEF	Inyo, San Bernardino	3 hr
Sep 19, 4:10 PM PDT	Areal Flood Advisory	VEF	Mohave	3 hr

Nearby

Severe Thunderstorm Warnings in California, 2025 Every severe thunderstorm warning in 2025

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.