Arctic Valley – Gordon Lyon

Red Flags of Instability:

• Remote triggered soft slab avalanche above a slightly wind loaded gully sidewall while descending
• Subtle collapsing/settlement/whoomphing while climbing out of the N-NW Gordon Lyon bowl
• Small pockets of wind slab triggered by cornice drops along the ridgeline (NNW aspect)

Weather:

• Very light snowfall
• Light wind from the SE
• Temps in the mid 20’s
• Low visibility with mostly obscured skies and flat light

Avalanche concerns:

Underlying the new snow, the slopes are littered with wind-affect from recent strong winds.  The wind-affected snow ranges from stout, supportable windboard to softer, breakable windboard to soft wind slab.  The new snow ranges from a dusting just below the peaks and ridges to several inches in sheltered areas.  In some places, the new snow has also been blown into fresh, soft, and shallow wind slabs.

With a winter weather advisory for snow in effect expect the avalanche hazard to increase accordingly.  Winds, however, are forecast to remain light through this snowfall event – while likely still strong enough to cause some loading in upper elevation starting zones.

Pockets of wind slab that were human triggered by an intentional cornice drop:

Remote-triggered soft slab on this typically wind-loaded gully sidewall: