Avalanche Forecast

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Monday night: Snow, up to 5 cm, moderate to strong southwest wind, freezing level 500 m.

Tuesday: Snow, 5-15 cm, strong southwest wind, alpine high -4, freezing level 1400 m.

Wednesday: Snow overnight 10-20 cm then clearing, strong southwest wind easing to moderate, alpine high -7, freezing level 1200 m.

Thursday: Sunny, light northwest wind, alpine high -7, freezing level 700 m with a weak inversion setting up.

Explosive work on Monday produced wind slabs up to size 1.5. Explosive cornice control work conducted on Saturday produced a size 1.5 cornice which did not trigger a heavily skied slope below, and a vehicle-triggered cornice drop tested a north facing alpine slope below, triggering a size 2 wind slab which did not step down to deeper layers.

Small amounts of new snow fall on wind affected surfaces at upper elevations, surface hoar in wind sheltered areas and a thin crust on solar aspects. Winds are likely redistributing new snow into wind slabs and growing cornices. 

A couple of persistent weak layers exist in the upper to mid snowpack:

• The upper layer, found 40-80 cm down, is a spotty layer of surface hoar at treeline and below. 
• The lower layer, found 90-150 cm down, is widespread and can present as surface hoar and/or a crust.

Avalanche activity on these layers has dwindled since last week and snowpack tests results have been moderate to hard planar, but not showing propagation. Incoming snowfall in the forecast for this week will add additional load to these layers and may shed some light on whether they will remain a concern.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Wind slabs are most reactive during their formation.
• Dial back your terrain choices if you are seeing more than 20 cm of new snow.