Avalanche Forecast

Spring temperatures in December?

Thursday: Mainly cloudy with some sunny periods. Alpine temperatures near +3 and ridgetop wind 20-30 km/hr from the southwest. Freezing levels 2000 m. 

Friday: A mix of sun and cloud. Alpine temperatures near +4 and ridgetop wind strong from the southwest. Freezing levels 1500 m.

Saturday: Cloudy with sunny periods and light precipitation. Alpine temperatures near +6 and ridgetop wind moderate to strong from the South. Freezing levels 2300 m. 

On Wednesday, in the northern part of the region, several natural avalanches were reported up to size 2 with some older ones from the previous storm up to size 2.5. A couple of isolated natural glide crack avalanches up to size 1.5 were also reported. 

On Tuesday, a large size 3 natural avalanche was observed on a NE aspect at 2400 m. It was reported as a cornice failure triggering the slope below and appeared to have slid on the early November crust near the base of the snowpack.

Our eyes and ears in the mountains are limited at this time of year and may continue this winter due to fewer professional observations. If you see anything (or don't) while out in the field, please consider sharing via the Mountain Information Network (MIN). Photos are especially helpful! Thank you so much for all the great MINs submitted so far!

It's a very dynamic period and the snowpack doesn't like rapid change.

Recent sun and warm air well into the alpine on Wednesday likely had the greatest impact on the upper snowpack, showing signs of instability and promoting further slab development and cohesion. This may be most concerning where these slabs sit above an old thin crust on south aspects and feathery surface hoar crystals in wind-sheltered areas. Northerly aspects will likely see fresh wind slab development at upper elevations on leeward slopes and melt-freeze conditions may exist on most aspects and elevations.

The lower snowpack is characterized by a few crusts formed during warm periods over the last month. 

• In the north, treeline snowpack depth sits around 80 to 120 cm. The crust of note here is sitting near the base of the snowpack, likely surrounded by a weak layer of sugary facets. Snowpack tests and recent avalanche activity suggest that this layer could be triggered by humans and produce large avalanches.
• In the south of the region, the snow line has been reported around 700 m near Hope, and treeline snowpack depth sits around 80-150 cm. Melt-freeze snow surfaces likely exist after the rapid warming on Wednesday. The deeper crusts in this area are generally down around 60-80 cm in the alpine and well bonded to surrounding snow.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Avoid steep slopes when air temperatures are warm, or solar radiation is strong.
• The likelihood of deep persistent slab avalanches will increase with each day of warm weather.