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Avalanche Forecast

Archived

Feb 2nd, 2024–Feb 3rd, 2024

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

Regions

Kananaskis, Bow Valley, Highwood Pass, North 40, Spray - KLakes.

Tricky times out there. We are expecting an upslope storm to arrive overnight and last for a day or two. Timing and amounts of snow are questionable, which also adds some uncertainty to the ratings. The underlying (pun intended) issue is the crust and how it will interact with the new snow. Watch this interface very carefully!

Confidence

Low

Avalanche Summary

No new avalanche were observed,

Snowpack Summary

Temperatures today were once again above zero, but not nearly what we've experienced for the past while. With that in mind, lets talk crusts. If the existing moist snow freezes completely, and it looks like it will, expect the crust surface to be hard, smooth and a poor bonding surface for the new snow. Ideally the snow will retain some heat as the snow starts, but this may not happen on all aspects. The glass-half-full situation is the crust remains slightly damp and bonds well with the new snow; and the glass-half-empty scenario is the crust will freeze solid, which will make for a potentially poor bonding surface. In reality, we'll probably see a little bit of both depending on aspect/elevation. As for the rest of the snowpack, Beneath the crust is, and will stay moist for some time. Down the road this could cause a couple of issues, but lets leave that discussion for a different day.

Weather Summary

Winter...is that you? Tomorrow will see a dramatic change in our weather pattern. Cooling will start this afternoon, followed by snow starting around midnight. Before we talk incoming snow, I'll elaborate on the temperatures as they'll be important. We'll have a few hours of cooling before the snow starts. Overnight low of -3, and then a steady drop during the afternoon to settle at -8 by late evening. The longer the cooling period is before the snow, the firmer (and possibly slipperier) the impending crust will be. Snow amounts will be a modest 5-10cm by tomorrow night with winds circling to a NE flow tomorrow morning. There is an upslope component to this storm, snow amounts will likely vary from the predicted.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Watch for unstable snow on specific terrain features, especially when the snow is moist or wet.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.