Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 9, NWS Reno, NV

August 13, 2021Alpine County, California

NWS Reno, NV issued this flash flood warning at Aug 13, 2021, 2:32 PM PDT for Alpine County, California. It was in force for 118 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 13, 2021, 2:32 PM PDT (21:32 UTC)
Expired: Aug 13, 2021, 4:30 PM PDT
In force: 118 min
Issued by: NWS Reno, NV
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Alpine County, CA

The radar

The Reno radar (KRGX), 122 km from the middle of the area, began a volume at 21:35 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

Reno, NV (KREV), launched 12:00Z, 9.5 hours before the alert went out and 172 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: 91 J/kg
Mixed-layer CIN: -234 J/kg
Mixed-layer LCL: 2718 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: -6 m²/s²
0-3 km storm-relative helicity: -47 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

460 
WGUS55 KREV 132132
FFWREV
CAC003-132330-
/O.NEW.KREV.FF.W.0009.210813T2132Z-210813T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Reno NV
232 PM PDT Fri Aug 13 2021

The National Weather Service in Reno has issued a

* Flash Flood Warning for...
  Alpine County in northern California...

* Until 430 PM PDT.

* At 232 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain on the west side of the Tamarack Fire Burn Scar. Flash 
  flooding and debris flow are possible through Grover Hot Springs 
  State Park.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Hot Springs Creek and Sawmill Creek. The debris 
flow can consist of rock, mud, vegetation and other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Grover Hot Springs, Turtle Rock Campground and Markleeville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 3867 11988 3870 11990 3872 11987 3872 11977
      3868 11975

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

TF

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 13, 3:01 PM PDT	Areal Flood Advisory	REV	Nevada, Placer	3 hr
Aug 13, 3:03 PM PDT	Special Weather Statement	REV	Alpine, Mono, Plumas	72 min

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.