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Avalanche Forecast

Archived

Feb 15th, 2022–Feb 16th, 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.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Purcells.

Manage open slopes at treeline with caution, persistent slab avalanches are most likely here.

Avalanches are unlikely where a thick surface crust exists.

Confidence

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

Weather Forecast

TUESDAY NIGHT: Partly cloudy with a light flurries. Moderate northwest winds with freezing levels at valley bottom.

WEDNESDAY: A mix of sun and cloud. Chance of flurries. Moderate northwest winds, alpine high of -3 with 1300m freezing levels. 

THURSDAY: Increasing cloud. Chance of flurries. Strong northwest winds. Freezing levels rise toward 2000 m. Alpine high of +1. 

FRIDAY: Cloudy with isolated flurries. Strong northwest winds. Freezing levels remain around 2000 m. Alpine high +2. 

Avalanche Summary

Avalanche activity on the January 30th surface hoar weak layer increased last week as a result of the warmer temperatures, on all aspects at treeline elevations. This layer is now below a thick melt freeze crust in most areas. Cornice control using explosives occurred on Monday, without triggering slabs on the slope below. 

Snowpack Summary

Up to 5 cm of new snow overlies a variety of surfaces. Higher elevations have been heavily wind effected, and a melt freeze crust exists on solar aspects to 2400 m. Lower elevations hold a widespread thick melt freeze on all aspects, surface hoar sits above the crust in sheltered terrain features. 

The late January interface is buried 20-50cm deep, and consists of a melt-freeze crust at lower elevations and on solar aspects extending into the alpine. Surface hoar sits above the crust in sheltered areas at treeline and below.

Several surface hoar layers are now buried in the upper snowpack 40-120cm deep. The snowpack below is well consolidated, with the early-December crust/facet persistent weak layer buried 80-150 cm deep. It is currently considered dormant. We expect this layer to become active later this season, check out the forecaster blog for more information.

Terrain and Travel

  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
  • Be alert to conditions that change with aspect and elevation.

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.