Avalanche Forecast

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

Monday night: Flurries, up to 5 cm, high wind gradient with elevation, light at 2000 m, strong at 3000 m southwest, freezing level 500 m.

Tuesday: Flurries, up to 10 cm, high wind gradient with elevation, light at 2000 m, strong at 3000 m southwest, alpine high -5, freezing level 1100 m.

Wednesday: Snow overnight then clearing, 10-20 cm, strong southwest wind, alpine high -4, freezing level 1500 m dropping through the day.

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

Over the weekend we received reports of a couple of natural wind slabs size 1.5, and solar triggered loose snow avalanches size 1-2.

Two human triggered avalanche incidents occurred last Tuesday; a size 1.5 on surface hoar in a northeast facing burn near Glacier National Park (view MIN report here), and a size 2.5 avalanche on an east aspect at treeline in the Lower Holt area, near Golden (view report here).

We have not had any reports of deep persistent slab avalanches on the basal weak layers for over a week.

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 few persistent weak layers exist in the upper to mid snowpack:

• The upper layer, found 40-60 cm down, is a spotty layer of surface hoar at treeline and below. 
• The lower layer, found 90-140 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 still 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.

The lower snowpack is characterized by more crusts, the most notable is a rain crust from early November that is near the base of the snowpack, surrounded by a weak layer of sugary facets. It is most likely to be reactive to human triggers in steep, shallow, rocky areas with a thin to thick snowpack.

• Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
• Dial back your terrain choices if you are seeing more than 20 cm of new snow.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.