Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 12, NWS Reno, NV

October 24, 2021Lassen County, Plumas County, California

NWS Reno, NV issued this flash flood warning at Oct 24, 2021, 6:42 AM PDT for Lassen County, Plumas County, California. It was in force for 20 hr. 3 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 24, 2021, 6:42 AM PDT (13:42 UTC)
Expired: Oct 25, 2021, 3:00 AM PDT
In force: 20 hr
Issued by: NWS Reno, NV
Area: Storm-based polygon
Flood severity: None

Counties Lassen County, CA, Plumas County, CA

The radar

The Reno radar (KRGX), 66 km from the middle of the area, began a volume at 13:44 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

Time	Report	Where	Remark
Oct 24, 8:00 AM PDT	HEAVY RAIN 1	3 Sse Frenchman Lake, CA	MESONET STATION FHDC1 2.7 SE FRENCHMAN LAKE.
Oct 24, 8:38 AM PDT	FLASH FLOOD	1 S Doyle, CA	CALIFORNIA HIGHWAY PATROL REPORTED 3.5 FEET OF WATER OVER THE ROAD ON THE NORTH END OF CONSTANTIA ROAD, ROAD IS IMPASSABLE.
Oct 24, 4:00 PM PDT	HEAVY RAIN 4.16	3 Sse Frenchman Lake, CA	MESONET STATION FHDC1 2.7 SE FRENCHMAN LAKE.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Reno, NV (KREV), launched 12:00Z, 1.7 hours before the alert went out and 175 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: 1043 m above ground
0-6 km bulk shear: 65 kt
0-1 km storm-relative helicity: 270 m²/s²
0-3 km storm-relative helicity: 689 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

598 
WGUS55 KREV 241342
FFWREV
CAC035-063-251000-
/O.NEW.KREV.FF.W.0012.211024T1342Z-211025T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Reno NV
642 AM PDT Sun Oct 24 2021

The National Weather Service in Reno has issued a

* Flash Flood Warning for...
  The Beckworth burn scar in...
  Southeastern Lassen County in northern California...
  Plumas County in northern California...

* Until 300 AM PDT Monday.

* At 642 AM PDT, Doppler radar indicated heavy rain over the 
  Beckworth Burn Scar. Flash flooding is ongoing or expected to 
  begin shortly.

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

  HAZARD...Flash flooding caused by heavy rain in and around the
           Beckworth Burn Scar.

  SOURCE...Radar.

  IMPACT...Flooding of areas in and around the Beckworth Burn
           Scar.

* Some locations that will experience flash flooding include...
  Doyle, Frenchman Lake, Chilcoot-Vinton, Frenchman Campground, Big 
  Cove Campground, Spring Creek Campground, Chilcoot Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life threatening situation. Heavy rainfall will cause 
extensive and severe flash flooding of creeks...streams...and 
ditches in the Beckworth Burn Scar. Severe debris flows can also be 
anticipated across roads. Roads and driveways may be washed away in 
places. If you encounter flood waters...climb to safety.

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads, and normally dry stream beds is likely. The heavy 
rains will likely trigger rockslides, mudslides and debris flows in 
steep terrain, especially in and around these areas.

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

&&

LAT...LON 4011 12019 4010 12018 4009 12016 4004 12009
      3998 12003 3992 12000 3985 12002 3983 12013
      3981 12022 3981 12029 3982 12036 3986 12036
      3994 12031 4006 12028

FLASH FLOOD...RADAR INDICATED

$$

Tolby

1 follow-up statement

247 
WGUS75 KREV 242032
FFSREV

Flash Flood Statement
National Weather Service Reno NV
132 PM PDT Sun Oct 24 2021

CAC035-063-251000-
/O.CON.KREV.FF.W.0012.000000T0000Z-211025T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lassen CA-Plumas CA-
132 PM PDT Sun Oct 24 2021

...FLASH FLOOD WARNING FOR THE BECKWORTH BURN SCAR REMAINS IN EFFECT 
UNTIL 3 AM PDT MONDAY FOR SOUTHEASTERN LASSEN AND PLUMAS COUNTIES...

At 132 PM PDT, Doppler radar indicated heavy rain over the Beckworth 
Burn Scar. Flash flooding is ongoing or expected to begin shortly.

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

HAZARD...Flash flooding caused by heavy rain in and around the
         Beckworth Burn Scar.

SOURCE...Radar.

IMPACT...Flooding of areas in and around the Beckworth Burn Scar.

Some locations that will experience flash flooding include...
Doyle, Frenchman Lake, Chilcoot-Vinton, Frenchman Campground, Big 
Cove Campground, Spring Creek Campground, Chilcoot Campground.

The heaviest rain rates are anticipated this afternoon into the 
early evening.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life threatening situation. Heavy rainfall will cause 
extensive and severe flash flooding of creeks...streams...and 
ditches in the Beckworth Burn Scar. Severe debris flows can also be 
anticipated across roads. Roads and driveways may be washed away in 
places. If you encounter flood waters...climb to safety.

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads, and normally dry stream beds is likely. The heavy 
rains will likely trigger rockslides, mudslides and debris flows in 
steep terrain, especially in and around these areas.

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

&&

LAT...LON 4011 12019 4010 12018 4009 12016 4004 12009
      3998 12003 3992 12000 3985 12002 3983 12013
      3981 12022 3981 12029 3982 12036 3986 12036
      3994 12031 4006 12028

FLASH FLOOD...RADAR INDICATED

$$

DJ

The office that day

Everything else NWS Reno, NV issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 24, 6:11 AM PDT	Flash Flood Warning	REV	Lassen, Plumas	21 hr
Oct 24, 8:00 AM PDT	Areal Flood Advisory	REV	Lassen, Plumas, Sierra	3 hr
Oct 24, 11:12 AM PDT	Areal Flood Warning	REV	Lassen, Nevada, Plumas, Sierra	2 hr
Oct 24, 1:19 PM PDT	Areal Flood Warning	REV	Alpine, El Dorado, Lassen, Nevada, Placer, Plumas and 1 more	8 hr
Oct 24, 3:27 PM PDT	River Flood Warning	REV	Nevada, Placer	11 hr
Oct 24, 4:47 PM PDT	Areal Flood Warning	REV	Alpine, El Dorado, Mono	12 hr

Nearby

Flash Flood Warnings in California, 2021 Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.