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Avalanche Forecast

Archived

Nov 19th, 2020–Nov 20th, 2020

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

Regions

Kananaskis.

15-25cm of snow over the past few days is adding load to the November crust down 30-50cm. This and new windslabs due to moderate variable winds are giving us a complex early season snowpack.  

Confidence

Moderate -

Weather Forecast

Steady light snowfalls will continue over the next few days but accumulations will be minimal. Temperatures will be more seasonal around -10C over the next few days with winds continuing in the moderate range mainly out of the SW.

Avalanche Summary

No new slab avalanche activity but a few loose dry avalanche out of steep terrain up to sz 1.5 were observed. 

Snowpack Summary

20-25cm of snow has fallen over the past 48hrs with variable winds at the upper elevations. WIndslabs in the upper snowpack are evident in alpine areas and there is also a layer of weak facets overlying the November rain crust that is producing moderate sudden planar failures down 30-40cm. Thin areas persist where triggerring the facets overlying the november crust may be easier and also the chance of clipping a rock or tree at lower elevations are very real as its still pretty thin. The crust is being found up to 2550m and is carrying a skeirs weight well. 

Terrain and Travel

  • Be careful as you transition into wind affected terrain.
  • Approach lee and cross-loaded slopes with caution.
  • Closely monitor how the new snow is bonding to the crust.
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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.