Alert archive / California / Flash Flood Warnings in 2020

Flash Flood Warning 8, NWS Los Angeles, CA

August 19, 2020Los Angeles County, California

NWS Los Angeles, CA issued this flash flood warning at Aug 19, 2020, 3:48 PM PDT for Los Angeles County, California. It was in force for 66 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: Aug 19, 2020, 3:48 PM PDT (22:48 UTC)
Expired: Aug 19, 2020, 4:54 PM PDT
In force: 66 min
Issued by: NWS Los Angeles, CA
Area: Storm-based polygon
Flood severity: None

County Los Angeles County, CA

The radar

The Santa Ana Mts radar (KSOX), 71 km from the middle of the area, began a volume at 22:49 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, 10.8 hours before the alert went out and 184 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: 165 J/kg
Mixed-layer CIN: -875 J/kg
Mixed-layer LCL: 2068 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 10 m²/s²
0-3 km storm-relative helicity: 37 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 flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Los Angeles, CA wrote its last area forecast discussion before this flash flood warning went out at Aug 19, 2:36 PM PDT, 1 hour 12 minutes earlier.

Area forecast discussion, Aug 19, 2:36 PM PDT, 1 hour 12 minutes before

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In the hours before

Special weather statement, Aug 19, 3:04 PM PDT, 44 minutes before

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Local storm report, Aug 19, 3:38 PM PDT, 10 minutes before

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  <main class="wrap">
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      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
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        Please try again in a few minutes.
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The office that day

Everything else NWS Los Angeles, CA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 18, 5:01 PM PDT	Special Weather Statement	LOX	Ventura	59 min
Aug 18, 5:15 PM PDT	Flash Flood Warning	LOX	Ventura	115 min
Aug 18, 9:26 PM PDT	Gale Watch	LOX		29 hr
Aug 18, 9:26 PM PDT	Small Craft Advisory	LOX		4 days
Aug 19, 1:55 PM PDT	Flash Flood Warning	LOX	Los Angeles	79 min
Aug 19, 3:04 PM PDT	Special Weather Statement	LOX	Los Angeles	56 min

Nearby

Flash Flood Warnings in California, 2020 Every flash 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.