Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Dec 4th, 2022–Dec 5th, 2022

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Lizard-Flathead, Akamina, Flathead, Lizard.

Diligently watch for changing conditions throughout the day. As the winds pick up, there's a lot of loose snow available to be transported into fresh, reactive wind slabs.

A weak layer of surface hoar continues to be a concern, particularly around treeline. Uncertainty surrounding this layer is best managed by conservative terrain choices and a cautious approach to risk management.

Confidence

Moderate

Avalanche Summary

On Sunday, a MIN report from Tunnel Creek reported reactivity in a snowpack test on the Mid-November layer on a south aspect. In this area, the layer presented as facets on a crust. They also observed a large natural avalanche on a west-facing slope at treeline. (Thanks for the report- ESPETERS10)

On Saturday, a small (size 1.5) skier triggered persistent slab avalanche occurred on an east-facing slope at treeline.

Numerous reports of small loose dry avalanches (sluffing) have been reported within the recently fallen low-density surface snow.

We have very few eyes out there. If you do get out please consider reporting in the MIN.

Snowpack Summary

Up to 100 cm of recent storm snow has fallen within the last week. In wind-affected terrain, this new snow has been redistributed into deeper deposits by recent variable winds. In sheltered terrain, cold temperatures will likely maintain low-density, powdery snow.

The middle of the snowpack consists of weak sugary layers of facets and surface hoar. A widespread rain crust remains near the ground at treeline and below treeline.

At treeline, snowpack depths vary from 120-200 cm.

Weather Summary

Sunday night

Mainly cloudy, light snowfall possible with trace accumulation. Southeasterly winds 5-15 km/h at ridgetop. Treeline temperature drops to -14 C.

Monday

Cloudy with snowfall, up to 5 cm of accumulation. Westerly wind 15-40 km/h at ridgetop. Treeline temperatures reach a high of -10 C.

Tuesday

Cloudy with snowfall, up to 5 cm of accumulation. Westerly wind 5-25 km/h at ridgetop. Treeline temperatures reach a high of -12 C.

Wednesday

Cloudy with snowfall, 1-3 cm of accumulation. Southwesterly wind 15-40 km/h at ridgetop. Treeline temperatures reach a high of -8 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

Problems

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.

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.