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

Feb 1st, 2022–Feb 2nd, 2022

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

Regions

South Rockies.

Treat open slopes at treeline and below as suspect, new snow sits on a weak surface hoar layer. Watch for signs of instability like shooting cracks and whumpfing.

Wind slabs will continue to form at higher elevations as westerly winds strengthen.

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Arctic air brings cold temperatures, wind and little chance of snow until Friday.

TUESDAY NIGHT: Scattered flurries continue. Light to moderate N winds. Freezing level at valley bottom. 

WEDNESDAY: A mix of sun and cloud. Moderate W winds. Freezing level at valley bottom. Alpine high of -15.

THURSDAY: A mix of sun and cloudy. Moderate W winds with strong gusts. Freezing level at valley bottom. Alpine high of -7.

FRIDAY: Cloudy. Moderate W winds with strong gusts. Freezing level at valley bottom. Alpine high of -4. Scattered flurries. 

Avalanche Summary

The recent storm produced a natural avalanche cycle to size 2. Small storm slabs and loose dry avalanches were also triggered by ski cutting and explosives on Monday. 

Shooting cracks and whumpfing were reported in the storm snow yesterday, indicating sensitivity in the buried surface hoar to human triggers. A Lizard-Flathead MIN report noted shooting cracks and whumpfing as well during their travel.

Snowpack Summary

At lower elevations up to 30cm of storm snow sits over a thick melt freeze crust, present up to 2000m. In sheltered terrain, a widespread layer of large surface hoar crystals sits immediately above the crust.

At higher elevations the storm snow is being redistributed by moderate to strong westerly winds, over a snow surface that was previously heavily wind affected. A thin melt freeze crust extends into the alpine on solar aspects. This crust may sit on the surface or below wind deposited snow. 

The early December crust/facet persistent weak layer is now 100-200 cm deep. This layer produced numerous very large avalanches during the third week of January but is now considered dormant after a week of cold, dry weather. While this layer is not currently considered a front page avalanche problem, we continue to track it and expect it will wake up again with major warming or a large storm event. This recent forecaster blog goes into more details on the layer.

Terrain and Travel

  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs may be poorly bonded to the underlying crust.

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.