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Avalanche Forecast

Archived

Jan 27th, 2023–Jan 28th, 2023

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

Regions

Glacier.

Fresh windslabs should stabilize quickly as temps cool, but may remain triggerable on Saturday.

The surface hoar layers from early January will linger for a little longer unfortunately. Skier traffic may have reduced the chances of triggering these persistent weaknesses on our the more popular runs, but approach terrain that is off the beaten path with extra caution.

Oh yeah...it's real cold again too, bring extra layers and leave yourself a little extra buffer to get out safely at the end of the day.

Confidence

High

Avalanche Summary

Artillery control on Friday produced numerous size 2-2.5, and a few size 3, slab avalanches in the Alpine and at Treeline. These are suspected to have been primarily windslabs, with some propagating more widely, suggesting failure on the early January surface hoar. These avalanches started as fast moving powder clouds, but quickly ground to a halt when they hit the refrozen snow mid-track (~1700m).

On Wednesday, a Skier triggered an avalanche on McGill shoulder,the failure plane for this was suspected to be an early January surface hoar layer down 50cm. Parks Canada staff also triggered soft slabs, up to size 1, down 30-40cm on a sun crust on steep solar aspects at treeline.

Snowpack Summary

Wind slabs formed recently in the alpine and at treeline with strong SW winds. Warm temps this week have left a surface crust below ~1700m, and a buried sun/temperature crust (Jan 21st) on steep south facing terrain, down 30-40cm around treeline.

The early January Surface Hoar layers (Jan 3rd and 12th), are buried down 40-70cm, and most likely to be rider triggered at treeline.

The mid-pack facets are slowly rounding and gaining strength, while large facetted crystals and the Nov 17 facet/SH/crust weakness can still be found near the base of the snowpack in many areas.

Weather Summary

An arctic ridge of high pressure will bring clear skies, cold temps and light outflow winds to our area through the weekend.

Tonight: Cloudy periods with isolated flurries. Alpine Low -22*C, Light NE ridgetop winds.

Saturday: Sunny. Alpine High -21*C. Light NE wind.

Sunday: Mostly Sunny. Low -22*C, High -19*C. Light NW winds.

Monday: Cloudy periods, isolated flurries. Low -19*C, High - 16*C. Light W wind.

Terrain and Travel Advice

  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

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.