Avalanche

4th of July

Davis, TylerGalena Summit & Eastern Mtns
View on map

Quick report

We observed no obvious signs of instability. Crusts in the upper snowpack did not produce unstable snowpack test scores. Deeper weak layers seemed unlikely to trigger in areas with a uniformly thick and dense overlying slab.

No signs of instability.

Weather

Cloud Cover
broken
Wind Loading
previous
Recent Snowfall
5 cm overnight
Snow Avail For Transport
small smounts

Overcast to start, with some large, lazy snowflakes that didn't accumulate. No noticeable wind, but we didn't travel on exposed ridges. Some blue patches started to open up midday. Mostly sunny in the Sawtooth Valley and mouths of major drainages in the afternoon.

Snowpack

Surface Snow
We found ~5 cm of new snow. We expected this new snow interface to look bad below the inversion and along the creek, but there was a notable lack of facets or surface here, just about 15 cm of snow atop the Christmas Eve crust. The new snow appeared to be bonding well everywhere we looked. 

Crusts:
The New Year temp/sun crust was most prominent at middle elevations above the inversion and on sunnier slopes. It was capped with ~5cm of moist snow. We dug to look at the Christmas Eve and Solstice rain crusts in many locations from 7,400-9,300'. We found 1 mm FC beneath the Christmas Eve crust that produced some rough shears. Overall, Christmas Eve looked worse, but neither looked alarming.

Basal Facets:
By the time we reached elevations with basal facets, the overlying slab had become very dense and thick. On a N @ 9,100, we found a 45 cm thick basal layer of moist, rounding facets interspersed with crusts. Hand harndesses ranged from 1F- to 4F+. The Overlying slab was 130 cm thick with over 50 cm of P- at the base. 

Avalanche

Size
D2
Count
9
Aspect
E
Trigger
N
Elevation
10000 ft

We observed several large and very large avalanches that failed during the Solstice and Christmas storms. These were focused on WNW-N-NE-E facing slopes above about 9,000'. We also observed a handful of smaller wind slab avalanches from the Christmas weekend storm.