Alert archive / California / Flash Flood Warnings in 2012

Flash Flood Warning 6, NWS Los Angeles, CA

October 11, 2012Los Angeles County, California

NWS Los Angeles, CA issued this flash flood warning at Oct 11, 2012, 2:55 PM PDT for Los Angeles County, California. It was in force for 98 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Oct 11, 2012, 2:55 PM PDT (21:55 UTC)
Expired
Oct 11, 2012, 4:33 PM PDT
In force
98 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), 58 km from the middle of the area, began a volume at 21:57 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

TimeReportWhereRemark
Oct 11, 2:58 PM PDTHEAVY RAIN 1.12 Nw Pasadena, CA1.10 INCHES OF RAINFALL IN 25 MINUTES AT DEVILS GATE AUTOMATED RAIN GAUGE.
Oct 11, 3:30 PM PDTFLASH FLOOD4 Nw Pasadena, CAFLASH FLOOD AND MUD FLOWS REPORTED IN LA CANADA. CROWN STREET WAS CLOSED BETWEEN FOOTHILL AVE AND BAPTISTE ST.

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, 9.9 hours before the alert went out and 176 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°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.

863 
WGUS56 KLOX 112155
FFWLOX
CAC037-112345-
/O.NEW.KLOX.FF.W.0006.121011T2155Z-121011T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE OXNARD CA
255 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...TUJUNGA...SUNLAND...SIERRA MADRE...
  LAKE VIEW TERRACE...LA CRESCENTA...LA CANADA/FLINTRIDGE...MONTEREY
  PARK...

* UNTIL 445 PM PDT

* AT 245 PM PDT...DOPPLER RADAR INDICATED STRONG AND NEARLY STATIONARY
  THUNDERSTORMS PRODUCING RAINFALL RATES IN EXCESS OF ONE INCH PER 
  HOUR ACROSS THE SAN GABRIEL MOUNTAINS AND FOOTHILLS. FLASH 
  FLOODING IS LIKELY ACROSS THE WARNING AREA. PEOPLE IN LOCATIONS 
  NEAR THE STATION FIRE BURN AREA SHOULD BE ESPECIALLY ALERT FOR
  FLOODING AND DEBRIS FLOWS.

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 3428 11789 3413 11778 3394 11815 3430 11840
      3439 11815

$$

GOMBERG/KJ
3 follow-up statements
745 
WGUS76 KLOX 112213
FFSLOX

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

CAC037-112345-
/O.CON.KLOX.FF.W.0006.000000T0000Z-121011T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LOS ANGELES CA-
313 PM PDT THU OCT 11 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 445 PM PDT FOR 
CENTRAL LOS ANGELES COUNTY...INCLUDING THE CITIES OF
LA CANADA FLINTRIDGE...ALTADENA...AND PASADENA...

AT 300 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO 
INDICATE A CLUSTER OF STRONG THUNDERSTORMS OVER CENTRAL LOS ANGELES
COUNTY...CAPABLE OF PRODUCING FLASH FLOODING. THE STRONGEST STORM 
WAS LOCATED OVER THE CITIES OF LA CANADA 
FLINTRIDGE...ALTADENA...MONTROSE...AND PASADENA...IMPACTING HIGHWAYS 
2 AND 210. THIS STORM WAS ALSO IMPACTING THE STATION FIRE BURN 
AREA...WHERE THERE IS STILL THE POTENTIAL FOR DEBRIS FLOWS.

VERY HEAVY RAIN HAS BEEN REPORTED WITH THESE STORMS...WITH DOPPLER 
RADAR ESTIMATING RAINFALL RATES OVER 1.5 INCHES PER HOUR. AN 
AUTOMATED GAUGE AT DEVILS GATE DAM REPORTED 1.22 INCHES OF RAIN 
BETWEEN 230 PM AND 3 PM.

IN ADDITION TO VERY HEAVY RAINFALL...THESE THUNDERSTORMS ARE
PRODUCING SMALL HAIL AND FREQUENT LIGHTNING.


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 3428 11789 3413 11778 3394 11815 3430 11840
      3439 11815

$$

GOMBERG
791 
WGUS76 KLOX 112326
FFSLOX

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

CAC037-112345-
/O.CON.KLOX.FF.W.0006.000000T0000Z-121011T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LOS ANGELES CA-
426 PM PDT THU OCT 11 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 445 PM PDT FOR 
CENTRAL LOS ANGELES COUNTY...

AT 415 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO 
INDICATE A CLUSTER OF STRONG THUNDERSTORMS OVER CENTRAL LOS ANGELES 
COUNTY...CAPABLE OF PRODUCING VERY HEAVY RAIN AND FLASH FLOODING. 
THE STRONGEST STORMS WERE CURRENTLY LOCATED OVER EAST LOS ANGELES 
AND THE SAN GABRIEL VALLEY...IMPACTING THE CITIES OF ALHAMBRA...
MONTEREY PARK...MONTEBELLO...EL MONTE...AND ROSEMEAD.

DOPPLER RADAR HAS ESTIMATED RAINFALL RATES BETWEEN 1 AND 2 INCHES 
PER HOUR ACROSS THESE AREAS. MAJOR ROADWAYS IMPACTED BY THESE VERY 
HEAVY RAINS AND FLOODING INCLUDE HIGHWAYS 60 AND 101...AS WELL AS 
INTERSTATES 10...605...AND 710. 

BETWEEN 315 PM AND 415...AN AUTOMATED RAIN GAUGE AT FREMONT HEADQUARTERS
IN EAST LOS ANGELES REPORTED 1.34 INCHES OF RAIN...WHILE EATON WASH
REPORTED 1.10 INCHES.


LAT...LON 3428 11789 3413 11778 3394 11815 3430 11840 3439 11815

$$

GOMBERG
282 
WGUS76 KLOX 112333
FFSLOX

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

CAC037-112341-
/O.CAN.KLOX.FF.W.0006.000000T0000Z-121011T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LOS ANGELES CA-
433 PM PDT THU OCT 11 2012

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR CENTRAL LOS ANGELES
COUNTY...
 THE FLASH FLOOD WARNING HAS BEEN CANCELLED BUT WILL BE REPLACED     
 SHORTLY WITH ANOTHER FLASH FLOOD WARNING THAT WILL BE EXPANDED.

LAT...LON 3428 11789 3413 11778 3394 11815 3430 11840

$$

KAPLAN

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, 3:29 PM PDTSpecial Weather StatementLOXLos Angeles31 min
Oct 11, 3:35 PM PDTAreal Flood AdvisoryLOXLos Angeles115 min
Oct 11, 4:37 PM PDTFlash Flood WarningLOXLos Angeles113 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.