Alert archive / California / Flash Flood Warnings in 2010

Flash Flood Warning 21, NWS Los Angeles, CA

August 25, 2010Los Angeles County, California

NWS Los Angeles, CA issued this flash flood warning at Aug 25, 2010, 2:09 PM PDT for Los Angeles County, California. It was in force for 111 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
Aug 25, 2010, 2:09 PM PDT (21:09 UTC)
Expired
Aug 25, 2010, 4:00 PM PDT
In force
111 min
Issued by
NWS Los Angeles, CA
Area
Storm-based polygon
Flood severity
None

County Los Angeles County, CA

The nearest sounding before it

San Diego, CA (KNKX), launched 12:00Z, 9.2 hours before the alert went out and 195 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 2010-08-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2010-08-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -16 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2462 m above ground
0-6 km bulk shear
11 kt
0-1 km storm-relative helicity
-16 m²/s²
0-3 km storm-relative helicity
60 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.

800 
WGUS56 KLOX 252109
FFWLOX
CAC037-252300-
/O.NEW.KLOX.FF.W.0021.100825T2109Z-100825T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE OXNARD CA
209 PM PDT WED AUG 25 2010

THE NATIONAL WEATHER SERVICE IN OXNARD HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EAST CENTRAL LOS ANGELES COUNTY IN SOUTHWEST CALIFORNIA...  
  INCLUDING THE SOUTHEAST PORTION OF THE ANTELOPE VALLEY AND SAN  
  GABRIEL MOUNTAINS

* UNTIL 400 PM PDT

* AT 155 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  STRONG AND NEARLY STATIONARY THUNDERSTORMS OVER THE SOUTHEAST PORTION
  OF THE ANTELOPE VALLEY...AND THE ADJACENT FOOTHILLS OF THE SAN GABRIEL
  MOUNTAINS. DOPPLER RADAR ESTIMATED RAINFALL RATES LOCALLY OVER 2 INCHES
  PER HOUR...CAPABLE OF PRODUCING FLASH FLOODING IN THE WARNING AREA.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO BIG   
PINES...PEARBLOSSOM...LITTLEROCK...AND LLANO. MAJOR ROADWAYS IMPACTED
BY THIS STORM INCLUDE HIGHWAYS 18 AND 138.

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.
DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE 
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS 
SAFELY. MOVE TO HIGHER GROUND.

&&

LAT...LON 3438 11796 3447 11806 3456 11800 3461 11777
      3459 11766 3457 11766 3456 11765 3433 11763
      3432 11764

$$

GOMBERG
2 follow-up statements
250 
WGUS76 KLOX 252157
FFSLOX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE OXNARD CA
257 PM PDT WED AUG 25 2010

CAC037-252300-
/O.CON.KLOX.FF.W.0021.000000T0000Z-100825T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LOS ANGELES CA-
257 PM PDT WED AUG 25 2010

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 400 PM PDT FOR EAST 
CENTRAL LOS ANGELES COUNTY INCLUDING THE SOUTHEAST PORTION OF THE
ANTELOPE VALLEY AND EASTERN SAN GABRIEL MOUNTAINS...

AT 236 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE STRONG THUNDERSTORMS OVER THE SOUTHEAST PORTION OF THE ANTELOPE
VALLEY AND THE EASTERN SAN GABRIEL MOUNTAINS. BETWEEN 1 PM AND 240 PM...THE
STRONGEST STORM AFFECTED HIGHWAY 138...SOUTHEAST OF LLANO...EXTENDING
SOUTHWARD INTO THE SAN GABRIEL MOUNTAINS...INCLUDING THE CITIES OF BIG
PINES AND WRIGHTWOOD. THIS STRONG THUNDERSTORM COMPLEX WAS VERY SLOW 
MOVING...WITH A WEATHER SPOTTER IN WRIGHTWOOD ESTIMATING RAINFALL OF
AROUND 2 INCHES IN 30 MINUTES. IN ADDITION...4 TO 6 INCHES OF WATER
WAS FLOWING IN THE ROADWAYS...WITH FLOODING OF YARDS AND STREETS.

ADDITIONAL STORMS ARE DEVELOPING ON THE NORTHWEST FLANK OF THIS THUNDERSTORM
COMPLEX...MOVING TOWARDS PALMDALE...INCLUDING HIGHWAYS 14 AND 138.


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.
DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN
OXNARD.

&&

LAT...LON 3438 11796 3447 11806 3456 11800 3461 11777
      3459 11766 3457 11766 3456 11765 3433 11763
      3432 11764

$$

GOMBERG/DANIELSON
524 
WGUS76 KLOX 252259
FFSLOX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE OXNARD CA
359 PM PDT WED AUG 25 2010

CAC037-252305-
/O.EXP.KLOX.FF.W.0021.000000T0000Z-100825T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LOS ANGELES CA-
359 PM PDT WED AUG 25 2010

...THE FLASH FLOOD WARNING WILL EXPIRE AT 400 PM PDT FOR EAST CENTRAL
LOS ANGELES COUNTY...

THE INITIAL FLASH FLOOD WARNING FOR SOUTHEAST ANTELOPE VALLEY AND
THE ADJACENT SAN GABRIEL MOUNTAINS HAS EXPIRED. A NEWER FLASH FLOOD
WARNING REMAINS IN EFFECT FOR CENTRAL LOS ANGELES COUNTY INCLUDING
THE PALMDALE METROPOLITAN AREA...SOLEDAD CAYNON...AND CROWN FIRE
BURN AREA.

LAT...LON 3438 11796 3447 11806 3456 11800 3461 11777
      3459 11766 3457 11766 3456 11765 3433 11763
      3432 11764

$$

GOMBERG

HTTP://LANDSLIDES.USGS.GOV/RESEARCH/WILDFIRE

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 25, 1:46 PM PDTSpecial Weather StatementLOXLos Angeles59 min
Aug 25, 3:17 PM PDTSpecial Weather StatementLOXLos Angeles58 min
Aug 25, 3:24 PM PDTFlash Flood WarningLOXLos Angeles111 min

Nearby

Flash Flood Warnings in California, 2010Every flash flood warning in 2010

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.