Alert archive / California / Flash Flood Warnings in 2012

Flash Flood Warning 7, NWS Los Angeles, CA

October 11, 2012Los Angeles County, California

NWS Los Angeles, CA issued this flash flood warning at Oct 11, 2012, 4:37 PM PDT for Los Angeles County, California. It was in force for 113 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
Oct 11, 2012, 4:37 PM PDT (23:37 UTC)
Expired
Oct 11, 2012, 6:30 PM PDT
In force
113 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), 32 km from the middle of the area, began a volume at 23:37 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, 11.6 hours before the alert went out and 151 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 2012-10-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 64 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, San Diego, CA at 12:00Z on 2012-10-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 39 square meters per square second.1939587897117Sfc1 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
64 J/kg
Mixed-layer CIN
-36 J/kg
Mixed-layer LCL
719 m above ground
0-6 km bulk shear
75 kt
0-1 km storm-relative helicity
39 m²/s²
0-3 km storm-relative helicity
54 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.

454 
WGUS56 KLOX 112337
FFWLOX
CAC037-120130-
/O.NEW.KLOX.FF.W.0007.121011T2337Z-121012T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE OXNARD CA
437 PM PDT THU OCT 11 2012

THE NATIONAL WEATHER SERVICE IN OXNARD HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL LOS ANGELES COUNTY IN SOUTHWEST CALIFORNIA...
  THIS INCLUDES THE CITIES OF...EAST LOS ANGELES...MONTEREY PARK...
  HUNTINGTON PARK...AND MONTEBELLO...

* UNTIL 630 PM PDT

* AT 430 PM PDT...DOPPLER RADAR INDICATED A CLUSTER OF STRONG
  AND NEARLY STATIONARY THUNDERSTORMS OVER MUCH OF EAST LOS ANGELES
  AND SAN GABRIEL VALLEY. THESE STORMS WERE PRODUCING VERY HEAVY
  RAINFALL CAPABLE OF FLASH FLOODING WITH LOCAL RAINFALL RATES
  IN EXCESS OF TWO INCHES PER HOUR.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

&&

LAT...LON 3402 11772 3402 11773 3402 11776 3399 11779
      3395 11779 3389 11831 3417 11837 3421 11768
      3417 11767

$$

GOMBERG
2 follow-up statements
505 
WGUS76 KLOX 120006
FFSLOX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE OXNARD CA
506 PM PDT THU OCT 11 2012

CAC037-120130-
/O.CON.KLOX.FF.W.0007.000000T0000Z-121012T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LOS ANGELES CA-
506 PM PDT THU OCT 11 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 PM PDT FOR
CENTRAL LOS ANGELES COUNTY...INCLUDING THE CITIES OF EAST LOS
ANGELES...MONTEREY PARK...HUNTINGTON PARK...AND MONTEBELLO...

AT 450 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE STRONG AND NEARLY STATIONARY THUNDERSTORMS OVER MUCH OF EAST
LOS ANGELES AND SAN GABRIEL VALLEY. THESE STORMS HAVE A HISTORY OF
PRODUCING VERY HEAVY RAINFALL...CAPABLE OF PRODUCING FLASH FLOODING...AS
WELL AS MUD AND ROCK SLIDES. RAINFALL RATES BETWEEN ONE AND TWO INCHES PER
HOUR HAVE ALREADY BEEN OBSERVED. AN AUTOMATED GAUGE AT FREMONT HEADQUARTERS
IN EAST LOS ANGELES HAS REPORTED 1.81 INCHES OF RAIN BETWEEN 345 PM
AND 445 PM. 

CALIFORNIA HIGHWAY PATROL HAS REPORTED WIDESPREAD ROADWAY
FLOODING ACROSS THE LOS ANGELES BASIN THIS AFTERNOON. MORE SIGNIFICANT
FLASH FLOODING WITH MUD AND DEBRIS FLOW ACTIVITY HAS BEEN OBSERVED IN LA
CANADA FLINTRIDGE.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

&&

LAT...LON 3402 11772 3402 11773 3402 11776 3399 11779
      3395 11779 3389 11831 3417 11837 3421 11768
      3417 11767

$$

GOMBERG
468 
WGUS76 KLOX 120128
FFSLOX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE OXNARD CA
628 PM PDT THU OCT 11 2012

CAC037-120135-
/O.EXP.KLOX.FF.W.0007.000000T0000Z-121012T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LOS ANGELES CA-
628 PM PDT THU OCT 11 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 630 PM PDT FOR CENTRAL LOS
ANGELES COUNTY...

DOPPLER RADAR HAS INDICATED DECREASING COVERAGE AND INTENSITY OF
RAINFALL ACROSS LOS ANGELES COUNTY. THERE IS NO LONGER AN IMMEDIATE
THREAT OF LIFE THREATENING FLASH FLOODING...ALLOWING THE FLASH FLOOD
WARNING TO EXPIRE. HOWEVER..ISOLATED THUNDERSTORM ACTIVITY WILL CONTINUE
TO BRING THE THREAT OF MINOR ROADWAY FLOODING ACROSS THE LOS ANGELES
BASIN THROUGH THE EARLY EVENING HOURS...WHERE AN URBAN AND SMALL STREAM
FLOOD ADVISORY REMAINS IN EFFECT.

LAT...LON 3402 11772 3402 11773 3402 11776 3399 11779
      3395 11779 3389 11831 3417 11837 3421 11768
      3417 11767

$$

GOMBERG

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 11, 4:02 AM PDTSpecial Marine WarningLOX28 min
Oct 11, 4:09 AM PDTSpecial Weather StatementLOXLos Angeles51 min
Oct 11, 5:41 AM PDTSpecial Marine WarningLOX49 min
Oct 11, 6:26 AM PDTSpecial Marine WarningLOX34 min
Oct 11, 6:31 AM PDTSpecial Weather StatementLOXLos Angeles44 min
Oct 11, 6:32 AM PDTSpecial Weather StatementLOXLos Angeles43 min
Oct 11, 8:32 AM PDTSpecial Marine WarningLOX58 min
Oct 11, 8:50 AM PDTSpecial Marine WarningLOX55 min
Oct 11, 10:00 AM PDTSpecial Marine WarningLOX60 min
Oct 11, 12:39 PM PDTAreal Flood AdvisoryLOXLos Angeles111 min
Oct 11, 12:54 PM PDTAreal Flood AdvisoryLOX111 min
Oct 11, 1:02 PM PDTFlash Flood WarningLOXVentura3 hr
Oct 11, 1:35 PM PDTAreal Flood AdvisoryLOXLos Angeles115 min
Oct 11, 1:51 PM PDTAreal Flood AdvisoryLOXSanta Barbara114 min
Oct 11, 2:47 PM PDTSpecial Weather StatementLOXLos Angeles28 min
Oct 11, 2:55 PM PDTFlash Flood WarningLOXLos Angeles98 min
Oct 11, 3:29 PM PDTSpecial Weather StatementLOXLos Angeles31 min
Oct 11, 3:35 PM PDTAreal Flood AdvisoryLOXLos Angeles115 min
Oct 11, 4:46 PM PDTSpecial Marine WarningLOX29 min
Oct 11, 4:54 PM PDTSpecial Weather StatementLOXOrange51 min

Nearby

Flash Flood Warnings in California, 2012Every flash flood 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.