Observation type
Avalanche

Observer
Alex Reed / Ethan 

Keep me anonymous if published
no

Location (general area)
Grinnell Mountain

Latitude

Longitude

Date (yyyymmdd)
2023/03/17

Time
7am-4pm

Road conditions to area
dry

Temperature
high 20's

Sky
few clouds (up to 2/8)

Wind speed
Calm (smoke rises vertically)

Wind direction
not observed

Wind direction in degrees

Slope aspect
North

Aspect in degrees

Slope angle
approx. 36 degrees, and approx 32 degrees.

Elevation
9500'-9250'

Snow depth
over 280cm

Boot/ Ski penetration

Precipitation
None

Activity, recent avalanches
yes

Brief description
skier trigger R1-D1 loose avalanche, and natural R1-D2

Whumphing noises, shooting cracks. collapsing
no

Rapid warming
no

Obvious avalanche path
no

Terrain trap
no

Comment
We observed a skier trigger R1-D1 loose avalanche at about 9500' on N aspect below tree-line, and an older natural R1-D2 avalanche on the N aspect at about 9250'. We were descending from Grinnell Mountain in the San Gorgonio area. 

The skier triggered R1-D1 may have been powerful enough to knock skier off their feet, but not big or powerful enough to bury anyone. It was caused when skiing through unconsolidated heavy snow on shaded/colder N aspect on a slope approx. 36 degrees. Loose debris ran for approx. 100 feet before coming to a stop. 

Skiers were well out of harms way in a safe zone.

Further down the descent, at approx. 9250' on N aspect we observed a natural avalanche that had occurred a few days prior. We did not see an obvious crown. Perhaps a loose point release stepped down into a crust? The debris visible do seem bonded in small blocks, indicating more structure in the snow than just a loose point release. 

Publish this observation
Yes I would like this observation Published

skier triggered loose release.

older natural avalanche.