Alert archive / California / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 2, NWS Los Angeles, CA

September 9, 2012Los Angeles County, California

NWS Los Angeles, CA issued this severe thunderstorm warning at Sep 9, 2012, 4:46 PM PDT for Los Angeles County, California. It was in force for 39 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, 2012, 4:46 PM PDT (23:46 UTC)
Expired
Sep 9, 2012, 5:25 PM PDT
In force
39 min
Issued by
NWS Los Angeles, CA
Area
Storm-based polygon

County Los Angeles County, CA

The radar

The Santa Ana Mts radar (KSOX), 64 km from the middle of the area, began a volume at 23:45 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, 11.8 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-pSkew-T log-p diagram, San Diego, CA at 12:00Z on 2012-09-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 145 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, San Diego, CA at 12:00Z on 2012-09-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 61 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
145 J/kg
Mixed-layer CIN
-540 J/kg
Mixed-layer LCL
1281 m above ground
0-6 km bulk shear
13 kt
0-1 km storm-relative helicity
61 m²/s²
0-3 km storm-relative helicity
77 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

976 
WUUS56 KLOX 092346
SVRLOX
CAC037-100045-
/O.NEW.KLOX.SV.W.0002.120909T2346Z-120910T0045Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE OXNARD CA
446 PM PDT SUN SEP 9 2012

THE NATIONAL WEATHER SERVICE IN OXNARD HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EAST CENTRAL LOS ANGELES COUNTY IN SOUTHWEST CALIFORNIA...

* UNTIL 545 PM PDT

* AT 439 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING NICKEL SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED 7 MILES
  NORTH OF FALLING SPRINGS...OR 21 MILES NORTHEAST OF SIERRA MADRE...
  AND MOVING SOUTHWEST AT 5 MPH.

* THE SEVERE THUNDERSTORM WILL CROSS OVER THE ANGELES CREST HIGHWAY 
  IN THE LOS ANGELES COUNTY MOUNTAINS WITHIN THE NEXT 10 MINUTES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

&&

LAT...LON 3423 11795 3443 11807 3452 11779 3436 11769
TIME...MOT...LOC 2343Z 064DEG 6KT 3440 11784

$$

HALL
1 follow-up statement
537 
WWUS56 KLOX 100025
SVSLOX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE OXNARD CA
525 PM PDT SUN SEP 9 2012

CAC037-100035-
/O.CAN.KLOX.SV.W.0002.000000T0000Z-120910T0045Z/
LOS ANGELES CA-
525 PM PDT SUN SEP 9 2012

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL LOS ANGELES 
COUNTY IS CANCELLED...

LAT...LON 3423 11795 3443 11807 3452 11779 3436 11769
TIME...MOT...LOC 0025Z 064DEG 6KT 3437 11792

$$

HALL

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 9, 3:32 AM PDTFlash Flood WatchLOX17 hr

Nearby

Severe Thunderstorm Warnings in California, 2012Every severe thunderstorm warning in 2012

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.