Alert archive / California / Flash Flood Warnings in 2011

Flash Flood Warning 13, NWS Los Angeles, CA

July 30, 2011Los Angeles County, California

NWS Los Angeles, CA issued this flash flood warning at Jul 30, 2011, 3:57 PM PDT for Los Angeles County, California. It was in force for 48 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: Jul 30, 2011, 3:57 PM PDT (22:57 UTC)
Expired: Jul 30, 2011, 4:45 PM PDT
In force: 48 min
Issued by: NWS Los Angeles, CA
Area: Storm-based polygon
Flood severity: None

County Los Angeles County, CA

What was reported inside it

Time	Report	Where	Remark
Jul 30, 4:50 PM PDT	FLOOD	9 Sse Lake Los Angeles, CA	WATER AT LEAST 1 FOOT DEEP ACROSS LARGO VISTA ROAD SOUTH OF HIGHWAY 138 NEAR CRYSTALAIRE.
Jul 30, 4:54 PM PDT	HEAVY RAIN 1.28	5 Se Pearblossom, CA	1.28 INCHES OR RAINFALL IN ONE HOUR AT VALYERMO RAWS...ELEVATION 3780 FEET.

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, 11.0 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-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: 657 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: 0 m²/s²
0-3 km storm-relative helicity: 44 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.

174 
WGUS56 KLOX 302257
FFWLOX
CAC037-302345-
/O.NEW.KLOX.FF.W.0013.110730T2257Z-110730T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE OXNARD CA
357 PM PDT SAT JUL 30 2011

THE NATIONAL WEATHER SERVICE IN OXNARD HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTHEASTERN ANTELOPE VALLEY AND NORTH SLOPES OF THE SAN GABRIEL
  MOUNTAINS IN EAST CENTRAL LOS ANGELES COUNTY...

* UNTIL 445 PM PDT

* AT 350 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  A THUNDERSTORM WITH VERY HEAVY RAIN LOCATED 6 MILES SOUTHEAST OF
  PEARBLOSSOM. FLASH FLOODING IS IMMINENT ALONG HIGHWAY 138 EAST OF
  PEARBLOSSOM.

* THE STORM PRODUCING FLASH FLOODING WILL REMAIN NEARLY STATIONARY
  THROUGH 430 PM PDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FLOODING IS OCCURRING OR IS IMMINENT. MOST FLOOD RELATED DEATHS OCCUR
IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED BRIDGES...
DIPS...OR LOW WATER CROSSINGS. NEVER TRY TO CROSS A FLOWING STREAM...
EVEN A SMALL ONE...ON FOOT. TO ESCAPE RISING WATER MOVE UP TO HIGHER
GROUND.

&&

LAT...LON 3454 11788 3454 11768 3439 11772 3439 11784

$$

SIRARD

2 follow-up statements

178 
WGUS76 KLOX 302320
FFSLOX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE OXNARD CA
420 PM PDT SAT JUL 30 2011

CAC037-302345-
/O.CON.KLOX.FF.W.0013.000000T0000Z-110730T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LOS ANGELES CA-
420 PM PDT SAT JUL 30 2011

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

AT 406 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A THUNDERSTORM PRODUCING VERY HEAVY RAIN OVER THE WARNED 
AREA. A NEW FLASH FLOOD WARNING WILL SOON BE ISSUED TO EXPAND THE 
AREA AND DURATION OF COVERAGE.

THIS THUNDERSTORM WITH EXCESSIVE RAIN WILL OTHERWISE REMAIN OVER
MAINLY RURAL AREAS OF THE INDICATED COUNTY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

&&

LAT...LON 3454 11788 3454 11768 3439 11772 3439 11784

$$

RK

004 
WGUS76 KLOX 302344
FFSLOX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE OXNARD CA
444 PM PDT SAT JUL 30 2011

CAC037-302352-
/O.EXP.KLOX.FF.W.0013.000000T0000Z-110730T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LOS ANGELES CA-
444 PM PDT SAT JUL 30 2011

...THE PREVIOUS FLASH FLOOD WARNING HAS BEEN REPLACED BY A NEW AND 
EXPANDED WARNING...

PLEASE REFERENCE THE LATEST FLASH FLOOD WARNING PRODUCT (LAXFFWLOX) 
FOR THE NEW WARNING FOR THE ANTELOPE VALLEY AND ADJACENT SAN GABRIEL 
FOOTHILLS.

LAT...LON 3454 11788 3454 11768 3439 11772 3439 11784

$$

RK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 30, 1:33 PM PDT	Areal Flood Advisory	LOX	Los Angeles	3 hr
Jul 30, 2:21 PM PDT	Small Craft Advisory	LOX		13 hr
Jul 30, 3:08 PM PDT	Special Weather Statement	LOX		22 min
Jul 30, 4:29 PM PDT	Flash Flood Warning	LOX	Los Angeles	3 hr

Nearby

Flash Flood Warnings in California, 2011 Every flash flood warning in 2011

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.