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Avalanche Forecast

Archived

Dec 14th, 2022–Dec 15th, 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 possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Rockies, Bull, Crowsnest North, Crowsnest South, Elkford East, Elkford West.

Watch for pockets of fresh wind slab at ridgetop. Elsewhere, fresh snow covers older wind slabs which may remain reactive to rider triggers.

A buried weak layer looms in the west and central parts of the region. Check out our latest blog for ways of managing persistent avalanche problems.

Confidence

Moderate

Avalanche Summary

A natural size 1.5 persistent slab avalanche was observed southeast of Elkford on Tuesday. It is suspected to have run on a weak layer buried in November that has been showing results in snowpack tests as well as signs of instability like whumpfing and cracking. In neighboring regions to the west and south, where it is buried deeper, reports of rider-triggered avalanche activity on this layer have been prolific. Unfortunately, more likely than not, this is a sign of what is to come for the west and central parts of the region.

Otherwise, avalanche activity in the region has been limited to explosive triggered wind slabs size 1-2 in the east of the region.

Snowpack Summary

Even in the notoriously windy Crowsnest, 5-10 cm of soft new snow remains fairly evenly distributed except at very exposed ridgetops. It sits over previously formed wind slabs at most elevations. Buried surface hoar has been observed beneath these aging wind slabs in the east of the region, which may keep them reactive where it exists.

A weak layer consisting of facets and surface hoar formed in November is now buried 45-65 cm deep in the west and central parts of the region. In the east, it may exist as a crust on solar aspects. This layer has been producing large avalanches in neighboring regions and has shown reactivity in snowpack tests here. This one is definitely on our radar!

The lower snowpack consists of sugary and faceted snow, with a thick rain crust near the ground.

Total snowpack depths at treeline elevations are 75 to 155 cm.

Weather Summary

Wednesday night

Clear. Light northerly wind. Alpine low -15 C.

Thursday

Sunny. Light northerly wind. Alpine high -7 C.

Friday

Mostly sunny. Ridgetop wind increasing to strong northwest as a cold front passes through. Alpine high -9 C.

Saturday

Mostly cloudy with scattered flurries in wake of the cold front. Moderate westerly ridgetop wind. Alpine high -10 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Recent new snow may be hiding windslabs that were easily visible before the snow fell.
  • Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.