Lizard Range and Flathead Avalanche Forecast

Issued: Feb 10th, 2021 3:00PM

Thu Feb 11th Current Conditions
Alpine Moderate Treeline Considerable Below Treeline Moderate
Fri Feb 12th 2 Day Outlook
Alpine Moderate Treeline Moderate Below Treeline Moderate
Sat Feb 13th 3 Day Outlook
Alpine Moderate Treeline Moderate Below Treeline Low

The alpine rating is moderate, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Persistent Slabs and Wind Slabs.

Yup, still cold. A conservative trip plan is a good idea when dealing with a persistent avalanche problem and extreme cold weather. 

Summary

Confidence

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

WEDNESDAY NIGHT - Partly cloudy / light north east wind / alpine low temperature near -30

THURSDAY - Cold and clear / light to moderate north east wind / alpine high temperature near -24

FRIDAY - Cold and sunny / light north east wind / alpine high temperature near -20

SATURDAY - Increasing cloud / light to moderate northeast wind / alpine high temperature near -20

Avalanche Summary

On Tuesday there were a couple of new skier triggered avalanches, including a remote triggered size 2 on Mt. Fernie (suspected surface hoar). Also on Tuesday, explosive control yielded wind slab avalanche results up to size 2.

On Monday, skiers accidentally triggered 2 small (size 1) avalanches down 45 cm, likely on surface hoar.

On Sunday a cornice failure triggered a small (size 1) avalanche with a 50 cm crown. Skiers reported sudden results in test profiles on prominent surface hoar on a variety of aspects buried 50 cm deep.

Last week was busy for avalanche activity, on Wednesday (Feb 3) persistent slab avalanche activity really picked up with reports of natural, human, and explosives triggered storm and/or persistent slab avalanches up to size 2 everyday through Saturday (Feb 6). 

On Saturday (Feb 6) riders continued to trigger slab avalanches 20-60 cm deep, documented in a handful of MIN reports (Trespass, Mammoth, Spicy, Different Day). Explosives triggered several large (2-2.5) persistent slab avalanches on northerly aspects below 2000 m.

On Friday (Feb 5), there were numerous reports of natural and human triggered persistent slab avalanches up to size 2.5. Some of these were triggered remotely, as outlined in a MIN report that can be viewed here. There were also numerous natural and explosives triggered dry loose, and storm slab avalanches reported up to size 2. 

Many thanks for all of the great MIN reports over the past week!

Snowpack Summary

Surface faceting and surface hoar growth is occurring with clear nights and frigid temperatures. Recent northerly and shifting winds have reverse loaded features, slabs may be found in lee terrain on a variety of aspects. 

A persistent weak layer lurks 30-70 cm below the surface, consisting of surface hoar, facets, and a crust buried in late January. This layer has been responsible for the majority of recent avalanche reports and has been easily found on all aspects, reports suggest it is touchiest on northerly and easterly aspects.

Below 1600 m a hard melt-freeze crust is underneath 20-40 cm recent snow. A solid mid-pack sits above a deeply buried crust and facet layers near the bottom of the snowpack (150-200 cm deep), which is currently unreactive. 

Terrain and Travel

  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Be aware of highly variable recent wind loading patterns.
  • Avoid terrain traps such as gullies and cliffs where the consequence of any avalanche could be serious.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Likely

Expected Size

1 - 2

As recently as Tuesday there were human triggered avalanches on this layer, including a size 2 remote triggered slide near Fernie. 40-65 cm snow sits above a buried weak layer of surface hoar, facets, and a crust. It has been most reactive at the treeline elevation on north through east aspects, but surface hoar continues to be reported in test profiles on all aspects. 

Aspects:

All aspects.

Elevations:

All elevations.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Variable winds may carry loose snow and build wind slabs in exposed and open features. Use caution around ridges, cornices, and loaded features. In steeper terrain, be cautious of dry-loose avalanches and mindful of sluffing.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Feb 11th, 2021 4:00PM

Forecast Trend

The latest forecast danger ratings, broken down to elevation. See how an elevation is trending.