Alert archive / California / Red Flag Warnings in 2020

Red Flag Warning 11, NWS Los Angeles, CA

December 5, 2020Los Angeles County, California

NWS Los Angeles, CA issued this red flag warning at Dec 5, 2020, 2:37 PM PST for Los Angeles County, California. It took effect at Dec 7, 2020, 4:00 AM PST. It was in force for 42 hr. 8 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Dec 5, 2020, 2:37 PM PST (22:37 UTC)
In effect from: Dec 7, 2020, 4:00 AM PST
Expired: Dec 8, 2020, 10:00 PM PST
In force: 42 hr
Issued by: NWS Los Angeles, CA

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 22:43 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.

What was reported inside it

Time	Report	Where	Remark
Dec 7, 11:20 AM PST	NON-TSTM WND GST 62	9 Ne San Fernando, CA	MESONET STATION SE678 MAGIC MTN TRUCK TRL (SCE).
Dec 7, 1:53 PM PST	NON-TSTM WND GST 70	8 Ese Castaic Lake, CA	MESONET STATION WMSC1 WARM SPRINGS RAWS.
Dec 7, 1:57 PM PST	NON-TSTM WND GST 58	2 N Santa Clarita, CA	MESONET STATION SAUC1 SAUGUS.
Dec 7, 6:53 PM PST	NON-TSTM WND GST 64	8 Nne Mount Wilson, CA	MESONET STATION CHOC1 CHILAO RAWS.
Dec 7, 8:40 PM PST	NON-TSTM WND GST 62	1 Nnw Chatsworth, CA	MESONET STATION SE712 BROWNS CYN (SCE).
Dec 7, 10:30 PM PST	NON-TSTM WND GST 68	9 Ne San Fernando, CA	MESONET STATION SE678 MAGIC MTN TRUCK TRL (SCE).
Dec 7, 10:53 PM PST	NON-TSTM WND GST 71	8 Ese Castaic Lake, CA	MESONET STATION WMSC1 WARM SPRINGS RAWS.
Dec 8, 1:20 AM PST	NON-TSTM WND GST 71	9 Ne San Fernando, CA	MESONET STATION SE678 MAGIC MTN TRUCK TRL (SCE).

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

San Diego, CA (KNKX), launched 12:00Z, 10.6 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 4772 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: 0 m²/s²
0-3 km storm-relative helicity: 23 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 red flag 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 red flag warning went out at Dec 5, 2:09 PM PST, 28 minutes earlier.

Area forecast discussion, Dec 5, 2:09 PM PST, 28 minutes before

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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
Dec 5, 1:02 PM PST	Beach Hazards Statement	LOX	Los Angeles	16 hr
Dec 5, 1:37 PM PST	Gale Watch	LOX		36 hr
Dec 5, 1:37 PM PST	Small Craft Advisory	LOX		4 days
Dec 5, 2:10 PM PST	High Wind Watch	LOX		24 hr
Dec 5, 2:10 PM PST	Hard Freeze Warning	LOX		19 hr
Dec 5, 2:37 PM PST	Fire Weather Watch	LOX		23 hr

Nearby

Red Flag Warnings in California, 2020 Every red flag 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.