Alert archive / California / Flash Flood Warnings in 2021
Flash Flood Warning 4, NWS Los Angeles, CA
NWS Los Angeles, CA issued this flash flood warning at Sep 10, 2021, 12:19 AM PDT for Los Angeles 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
- Sep 10, 2021, 12:19 AM PDT (07:19 UTC)
- Expired
- Sep 10, 2021, 3:00 AM PDT
- In force
- 3 hr
- 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), 59 km from the middle of the area, began a volume at 07:20 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 00:00Z, 7.3 hours before the alert went out and 178 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2385 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 7 m²/s²
- 0-3 km storm-relative helicity
- 90 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
304
WGUS56 KLOX 100719
FFWLOX
CAC037-101000-
/O.NEW.KLOX.FF.W.0004.210910T0719Z-210910T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Los Angeles/Oxnard CA
1219 AM PDT Fri Sep 10 2021
The National Weather Service in Los Angeles/Oxnard has issued a
* Flash Flood Warning for...
East Central Los Angeles County in southwestern California...
* Until 300 AM PDT.
* At 1219 AM PDT, Doppler radar and automated rain gauges indicated
line of thunderstorms producing heavy rain across the Bobcat and
Ranch 2 burn areas. Flash flooding and mud and debris flow are
ongoing or expected to begin shortly.
Excessive rainfall over the burn scar will result in mud and debris
flows. The debris flows can consist of rock, mud, vegetation and
other loose materials.
HAZARD...Debris flows are caused by thunderstorms.
SOURCE...Radar and automated gauges.
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...
Bobcat and Ranch 2 burn scars, Mount Wilson, Glendora, Monrovia,
Angeles Crest Highway between Mount Wilson and Mount Waterman,
Sierra Madre, Azusa, and Arcadia.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Flash Flood Warning for a recent burn area means that flooding and
debris flows are imminent or occurring. Residents living in or
immediately downstream should take immediate precautions to protect
life and property. Quickly move away from the burn area only if it
is safe to do so, otherwise shelter in place and move to a second
story or the highest location in your home to stay out of the path
of fast-moving water and debris flows.
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Please report observed flooding to local emergency services or law
enforcement and request they pass this information to the National
Weather Service when you can do so safely.
&&
LAT...LON 3427 11812 3435 11795 3435 11794 3418 11783
3414 11803
FLASH FLOOD...RADAR AND GAUGE INDICATED
$$
Hall3 follow-up statements
721
WGUS76 KLOX 100756
FFSLOX
Flash Flood Statement
National Weather Service Los Angeles/Oxnard CA
1256 AM PDT Fri Sep 10 2021
CAC037-101000-
/O.CON.KLOX.FF.W.0004.000000T0000Z-210910T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Los Angeles CA-
1256 AM PDT Fri Sep 10 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 3 AM PDT EARLY THIS
MORNING FOR EAST CENTRAL LOS ANGELES COUNTY...
At 1256 AM PDT, Doppler radar and automated rain gauges indicated
rainfall from showers and thunderstorms starting to taper off early
this morning. Heavy rain was observed across the Bobcat burn area
with two rain gages recording between a third and a half of an inch
of rainfall between ten and fifteen minutes. Flash flooding and mud
and debris flow are occurring or are expected to begin shortly.
Excessive rainfall over the Bobcat and Ranch 2 burn scars will
result in mud and debris flows. The debris flows can consist of
rock, mud, vegetation and other loose materials.
HAZARD...Debris flows caused by thunderstorms.
SOURCE...Radar and automated gauges.
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...
Bobcat and Ranch 2 burn scars, Mount Wilson, Glendora, Monrovia,
Angeles Crest Highway between Mount Wilson and Mount Waterman,
Sierra Madre, Azusa, and Arcadia.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Flash Flood Warning for a recent burn area means that flooding and
debris flows are imminent or occurring. Residents living in or
immediately downstream should take immediate precautions to protect
life and property. Quickly move away from the burn area only if it
is safe to do so, otherwise shelter in place and move to a second
story or the highest location in your home to stay out of the path
of fast-moving water and debris flows.
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Be especially cautious at night when it is harder to recognize the
dangers of flooding.
Please report observed flooding to local emergency services or law
enforcement and request they pass this information to the National
Weather Service when you can do so safely.
&&
LAT...LON 3427 11812 3435 11795 3435 11794 3418 11783
3414 11803
FLASH FLOOD...RADAR AND GAUGE INDICATED
$$
Hall254
WGUS76 KLOX 100905
FFSLOX
Flash Flood Statement
National Weather Service Los Angeles/Oxnard CA
205 AM PDT Fri Sep 10 2021
CAC037-101000-
/O.CON.KLOX.FF.W.0004.000000T0000Z-210910T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Los Angeles CA-
205 AM PDT Fri Sep 10 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 3 AM PDT EARLY THIS
MORNING FOR EAST CENTRAL LOS ANGELES COUNTY...
At 205 AM PDT, Doppler radar and automated rain gauges indicated
showers and thunderstorms continuing to stream over the Bobcat and
Ranch 2 burn scars early this morning. Heavy rain was observed
across the Bobcat burn area with two rain gages recording between a
third and a half of an inch of rainfall between ten and fifteen
minutes. Flash flooding and mud and debris flow are occurring or are
expected to begin shortly.
Excessive rainfall over the burn scar will result in mud and debris
flows. The debris flows can consist of rock, mud, vegetation and
other loose materials.
HAZARD...Debris flows caused by thunderstorms.
SOURCE...Radar and automated gauges.
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...
Bobcast and Ranch 2 burn scars, Mount Wilson, Glendora, Monrovia,
Angeles Crest Highway between Mount Wilson and Mount Waterman,
Sierra Madre, Azusa, and Arcadia.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Flash Flood Warning for a recent burn area means that flooding and
debris flows are imminent or occurring. Residents living in or
immediately downstream should take immediate precautions to protect
life and property. Quickly move away from the burn area only if it
is safe to do so, otherwise shelter in place and move to a second
story or the highest location in your home to stay out of the path
of fast-moving water and debris flows.
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Be especially cautious at night when it is harder to recognize the
dangers of flooding.
In hilly terrain there are hundreds of low water crossings which are
potentially dangerous in heavy rain. Do not attempt to cross flooded
roads. Find an alternate route.
Please report observed flooding to local emergency services or law
enforcement and request they pass this information to the National
Weather Service when you can do so safely.
&&
LAT...LON 3427 11812 3435 11795 3435 11794 3418 11783
3414 11803
FLASH FLOOD...RADAR AND GAUGE INDICATED
$$
Hall551
WGUS76 KLOX 100957
FFSLOX
Flash Flood Statement
National Weather Service Los Angeles/Oxnard CA
257 AM PDT Fri Sep 10 2021
CAC037-101007-
/O.EXP.KLOX.FF.W.0004.000000T0000Z-210910T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Los Angeles CA-
257 AM PDT Fri Sep 10 2021
...FLASH FLOOD WARNING WILL EXPIRE AT 3 AM PDT EARLY THIS MORNING
FOR EAST CENTRAL LOS ANGELES COUNTY...
Flood waters have receded and the threat of mud and debris flows is
diminishing. Water and muds may still be flowing through drainages
and channels. Please follow the directions of local law enforcement
and continue to heed remaining road closures.
LAT...LON 3427 11812 3435 11795 3435 11794 3418 11783
3414 11803
$$
HallThe office that day
Everything else NWS Los Angeles, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 9, 5:07 PM PDT | Areal Flood Advisory | LOX | Los Angeles | 3 hr |
| Sep 10, 12:01 AM PDT | Areal Flood Advisory | LOX | Los Angeles | 18 min |
| Sep 10, 9:01 AM PDT | Small Craft Advisory | LOX | 48 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.