Avalanche Forecast

Archived

Dec 10th, 2022–Dec 11th, 2022

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Glacier.

The recent low-density storm snow is settling out and showing increasing signs of slab properties. There is uncertainty that surrounds the persistent layers and when/if they will exhibit wide propagations. Assess the snowpack carefully before stepping out into committing terrain.

Confidence

Low

Avalanche Summary

Several slab avalanches up to size 2 on Saturday were observed along the highway corridor.

A loose dry cycle occurred on Friday from steep rocky terrain up to size 2.

Snowpack Summary

Up to 45cm of new snow now buries the Dec 5 layer, which consists of surface hoar, preserved stellars, facets, and a thin sun crust on steeper solar aspects.

Wind slab is likely to be found in the alpine and in open areas at treeline.

The Nov 17th Surface Hoar is now buried 60-90cm and continues to produce sudden results in snowpack tests.

Weather Summary

Snow flurries are forecasted for Sunday morning with a clearing trend by mid-afternoon as a high-pressure system settles into the region that will likely persist through the week.

Alpine temps of -10 to -6, light ridgetop winds, and a freezing level up to 1000m.

Sunny skies and light wind into next week.

Terrain and Travel Advice

Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.