Avalanche

WMR and Hellroaring Peak

blase reardonWhitefish Range
View on map
Observation photo 1

Quick report

I did an afternoon wander around in the terrain north and west of WMR. My objectives were to check out a slide triggered during this morning's avalanche mitigation efforts,  look for evidence of of the wind slab avalanche problem, and do my monthly beacon practice.

  • Evidence for the Wind Slab problem include the triggered slide (see avalanche link), and camoflaged under about 3 inches of fresh snow, hard, dense wind packed snow and drifts. These were unreactive. See Avalanche problems.
  • The parade of weak storms, bouts of strong winds, and brief sunny spells the past 10 days has left an upper snowpack that's complex and variable. The top 75-100 cm of the snowpack contains lots of thin layers that aren't uniform across a slope, or from slope to slope. Multiple distinct and sometimes weak interfaces. Sometimes thin, friable crusts. No distinct or reactive persistent weak layers. 
  • The most recent snow (~3 inches) is loose and cohesionless, and sluffs easily on steep slopes. It may not support a dense cohesive slab. 

The recent snow made for a great refresh. And the Gray Wolf beacon park makes it so easy to practice. Check it out. 

The most recent snow sluffed with turns on steep slopes. It ran on the surface and didn't entrain more snow.

Weather

Air Temp
25
Cloud Cover
broken
Wind Loading
previous
Recent Snowfall
8
Snow Avail For Transport
small smounts

partly sunny skies gave way to increasing and lowering clouds by mid afternoon. Brief moments when the summit was in the clouds. Felt warm. Winds calm or light.

Snowpack

The snow surface is < 10 cm of loose rimed precipitation particles. Various dense, wind packed layers immediately below that (various thicknesses), with thin weak interfaces between successive layers of drifted snow or storm snow. 

In a profile at 6650 on an east-facing slope (HS 120), the 12/7 pwl was buried about 70 cm below the surface. It's becoming less distinct, the facets are rounding, and the surface hoar is breaking down. The AR crust was at 35 cm. ECTN 15 on 12/7; ECTN 10 and 13 on storm interfaces.

Avalanche

Size
D1.5
Type
HS
Aspect
NE
Trigger
AB
Elevation
6650 ft

One hard slab triggered by an airblast on a steep, convex slope this morning.