Alert archive / California / Special Weather Statements in 2021

Special Weather Statement, NWS San Diego, CA

September 9, 2021

NWS San Diego, CA issued this special weather statement at Sep 9, 2021, 12:40 PM PDT. It was in force for 50 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 9, 2021, 12:40 PM PDT (19:40 UTC)
Expired: Sep 9, 2021, 1:30 PM PDT
In force: 50 min
Issued by: NWS San Diego, CA
Hail: 0.00 in
Wind: 40

The radar

The Edwards AFB radar (KEYX), 71 km from the middle of the area, began a volume at 19:41 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

San Diego, CA (KNKX), launched 12:00Z, 7.7 hours before the alert went out and 191 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: 15 J/kg
Mixed-layer CIN: -787 J/kg
Mixed-layer LCL: 1710 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 44 m²/s²
0-3 km storm-relative helicity: 112 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

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

NWS San Diego, CA wrote its last area forecast discussion before this special weather statement went out at Sep 9, 9:56 AM PDT, 2 hours 44 minutes earlier.

Area forecast discussion, Sep 9, 9:56 AM PDT, 2 hours 44 minutes before

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  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
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</head>
<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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In the hours before

Special weather statement, Sep 9, 12:40 PM PDT, 0 minutes before

Special Weather Statement
National Weather Service San Diego CA
1240 PM PDT Thu Sep 9 2021

CAZ055-060-092030-
Apple and Lucerne Valleys CA-San Bernardino County Mountains CA-
1240 PM PDT Thu Sep 9 2021

...A strong thunderstorm will impact portions of San Bernardino
County through 130 PM PDT...

At 1239 PM PDT, Doppler radar was tracking a strong thunderstorm near
Apple Valley, moving northwest at 20 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Victorville, Hesperia, Apple Valley, I-15 Between Victorville And
Barstow, Adelanto, Hwy 173 Between Lake Arrowhead And Hesperia, El
Mirage, Mountain View Acres, Oro Grande and Helendale.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3442 11706 3433 11725 3466 11752 3478 11723
TIME...MOT...LOC 1939Z 152DEG 17KT 3444 11720

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

JMB

The office that day

Everything else NWS San Diego, CA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 9, 1:05 PM PDT	Severe Thunderstorm Warning	SGX	San Bernardino	40 min
Sep 9, 1:19 PM PDT	Severe Thunderstorm Warning Considerable damage threat	SGX	San Bernardino	22 min
Sep 9, 2:12 PM PDT	Areal Flood Advisory	SGX	San Diego	3 hr
Sep 9, 2:34 PM PDT	Flash Flood Warning Considerable damage threat	SGX	San Bernardino	3 hr
Sep 9, 2:54 PM PDT	Severe Thunderstorm Warning	SGX	San Bernardino	66 min
Sep 9, 3:10 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Bernardino	50 min
Sep 9, 3:25 PM PDT	Special Weather Statement	SGX		50 min
Sep 9, 3:29 PM PDT	Flash Flood Warning Considerable damage threat	SGX	Riverside, San Bernardino	2 hr
Sep 9, 3:46 PM PDT	Areal Flood Advisory	SGX	Riverside	3 hr
Sep 9, 4:33 PM PDT	Flash Flood Warning Considerable damage threat	SGX	Riverside	88 min
Sep 9, 4:35 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Bernardino	55 min

Nearby

Special Weather Statements in California, 2021 Every special weather statement in 2021

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.