Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 5, NWS Los Angeles, CA

October 25, 2021Santa Barbara County, California

NWS Los Angeles, CA issued this flash flood warning at Oct 25, 2021, 8:22 AM PDT for Santa Barbara County, California. It was in force for 3 hr. 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 25, 2021, 8:22 AM PDT (15:22 UTC)
Expired
Oct 25, 2021, 11:15 AM PDT
In force
3 hr
Issued by
NWS Los Angeles, CA
Area
Storm-based polygon
Flood severity
None

County Santa Barbara County, CA

The radar

The Vandenberg AFB radar (KVBX), 48 km from the middle of the area, began a volume at 15:25 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

Vandenberg AFB, CA (KVBG), launched 12:00Z, 3.4 hours before the alert went out and 46 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, Vandenberg AFB, CA at 12:00Z on 2021-10-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 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, Vandenberg AFB, CA at 12:00Z on 2021-10-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 424 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
511 m above ground
0-6 km bulk shear
87 kt
0-1 km storm-relative helicity
424 m²/s²
0-3 km storm-relative helicity
537 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

811 
WGUS56 KLOX 251522
FFWLOX
CAC083-251815-
/O.NEW.KLOX.FF.W.0005.211025T1522Z-211025T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Los Angeles/Oxnard CA
822 AM PDT Mon Oct 25 2021

The National Weather Service in Los Angeles/Oxnard has issued a

* Flash Flood Warning for...
  Central Santa Barbara County in southwestern California...

* Until 1115 AM PDT.

* At 822 AM PDT, Doppler radar indicated heavy rain will move into 
  the warned area. The expected rainfall rate is 0.75 to 1 inch per 
  hour, with 30 minute rates likely exceeding 0.55 inches. Flash 
  flooding with debris flows is expected to begin shortly.

Excessive rainfall over the burn scar will result in debris flows 
moving through the Alisal burn scar. The debris flows can consist of 
rock, mud, vegetation and other loose materials.

  HAZARD...Debris flows caused by heavy rain.

  SOURCE...Radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Refugio State Beach and El Capitan State Beach.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3447 12021 3452 12020 3454 12008 3454 12003
      3454 12001 3452 11999 3450 11999 3449 11999
      3446 12001 3446 12003 3445 12008 3445 12014
      3447 12020

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.5-1 INCH IN 1 HOUR

$$

Gomberg
2 follow-up statements
665 
WGUS76 KLOX 251736
FFSLOX

Flash Flood Statement
National Weather Service Los Angeles/Oxnard CA
1036 AM PDT Mon Oct 25 2021

CAC083-251815-
/O.CON.KLOX.FF.W.0005.000000T0000Z-211025T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Barbara CA-
1036 AM PDT Mon Oct 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1115 AM PDT THIS 
MORNING FOR THE ALISAL BURN SCAR IN CENTRAL SANTA BARBARA COUNTY...

At 1036 AM PDT, Doppler radar indicated periods of heavy rain moving 
into the warning area. Brief heavy downpours could still exceed 15 
and 30 minute USGS thresholds through 1115 an.

Excessive rainfall over the burn scar will likely result in debris 
flows moving through the Alisal burn scar. The debris flows can 
consist of rock, mud, vegetation and other loose materials.

HAZARD...Debris flows caused by heavy rain.

SOURCE...Radar.

IMPACT...Flash flooding and debris flows in the Alisal Burn scar.

Some locations that will experience flash flooding include...
  the Alisal burn scar, Refugio State Beach and El Capitan State 
  Beach.

The automated rain gauge at Refugio Pass reported peak rainfall 
rates of 0.91 inches per hour, .55 inches in 30 minutes, and .36 
inches in 15 minutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3447 12021 3452 12020 3454 12008 3454 12003
      3454 12001 3452 11999 3450 11999 3449 11999
      3446 12001 3446 12003 3445 12008 3445 12014
      3447 12020

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.5-1 INCH IN 1 HOUR

$$

Gomberg
269 
WGUS76 KLOX 251820
FFSLOX

Flash Flood Statement
National Weather Service Los Angeles/Oxnard CA
1120 AM PDT Mon Oct 25 2021

CAC083-251830-
/O.EXP.KLOX.FF.W.0005.000000T0000Z-211025T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Barbara CA-
1120 AM PDT Mon Oct 25 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR THE ALISAL BURN SCAR IN 
CENTRAL SANTA BARBARA COUNTY...

The heavy rain has ended. Significant and damaging debris flows is 
no  longer expected to pose an immediate threat.Scattered showers 
are likely to continue through noon or 1 pm.


LAT...LON 3447 12021 3452 12020 3454 12008 3454 12003
      3454 12001 3452 11999 3450 11999 3449 11999
      3446 12001 3446 12003 3445 12008 3445 12014
      3447 12020

$$

Gomberg

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 25, 5:25 AM PDTAreal Flood AdvisoryLOXSan Luis Obispo3 hr
Oct 25, 7:34 AM PDTAreal Flood AdvisoryLOXSanta Barbara5 hr
Oct 25, 8:54 AM PDTAreal Flood AdvisoryLOXSan Luis Obispo, Santa Barbara3 hr
Oct 25, 10:09 AM PDTAreal Flood AdvisoryLOXVentura4 hr
Oct 25, 12:24 PM PDTAreal Flood AdvisoryLOXLos Angeles4 hr

Nearby

Flash Flood Warnings in California, 2021Every flash flood warning in 2021

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.