Avalanche Forecast

Archived

Apr 5th, 2024–Apr 7th, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

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

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

Windslabs in alpine terrain should be expected near cols and crests of features. The thin snowpack also is a concern in terms of triggering the deep persistent slab problem. Temperatures have stayed warm overnight and as a result, refreezes have been very limited. Conservative terrain choices is a good way to manage the uncertainty within the snowpack right now. Hopefully we get a good overnight freeze soon!

Confidence

Moderate

Avalanche Summary

A few loose dry avalanches from steep terrain up to sz 1.5.

Snowpack Summary

20-40cm of recent snow (40cm on the eastern side of the range) is overlying a temperature crust that developed early in the week. This crust is being found up to 2300m and while supportive to skiing, its sitting on top of a generally moist snowpack. Crusts are common on the solar aspects but less so on the more polar sides. There are some isolated windslabs in alpine areas along ridgelines but this problem does not appear to be widespread. Thin weak areas are getting harder to determine and during a tour on Friday forecasters were getting moderate results in the basal facets from thin <1m areas at treeline. Recent snow combined with cloudy weather hasnt allowed the snowpack to get a significant refreeze that is common for spring time. Conservative terrain was the place to be for us on Friday.

An important thing to consider at this time of year is the Quality of the freeze overnight. Over the past 2 days, freezes have been generally poor with overnight lows only around -5C. Avalanche danger can change from low in the cool mornings to high in the hot afternoons. The timing of this change is important to monitor so plan you trips with these factors in mind.

Weather Summary

Not much of a change for Saturday. Cloudy skies will continue which will limit our re-freeze and only a trace of new snow is forecast on Saturday. Freezing levels will rise from the valley floor to 2000m throughout the day. Winds are generally forecast to be light. If the sun comes out, expect avalanche danger to quickly increase.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Recent wind has varied in direction so watch for wind slabs on all aspects.

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.

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.