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Avalanche Forecast

Archived

Dec 20th, 2022–Dec 21st, 2022

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

Purcells, Dogtooth, East Purcell.

Very cold temperatures are likely the biggest hazard in the backcountry right now. Make conservative plans, even a small accident can have big consequences.

Confidence

Moderate

Avalanche Summary

No new avalanches have been reported in the past few days.

If you are headed into the backcountry please consider filling out a Mountain Information Network report.

Snowpack Summary

The upper snowpack at treeline and above is made up of wind effected surfaces and loose faceted snow in sheltered terrain.

The main layer of concern is the mid-November layer, which is made up of either surface hoar, facets, or crusts. It is now buried 40 to 80 cm deep. Avalanche activity on this layer has tapered off but it could still be possible to trigger this layer in isolated terrain features near treeline.

Alpine snowpack distribution is variable, with depths ranging from 70 to 140 cm.

Weather Summary

Tuesday Night

Flurries bringing trace amounts of new snow with light winds shifting from west to northeast by the morning. Low of -31 at -2000m.

Wednesday

Mostly sunny with no new snow expected. Light northeast winds and a high of -29 at 2000m.

Thursday

Mostly sunny with no new snow expected. Light variable winds and a high of -31 at 2000m.

Friday

Cloudy with trace amounts of new snow expected. Southwest winds increasing throughout the day. High of -25 at 2000m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.

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.