Avalanche Forecast

Issued: Mar 3rd, 2021 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Loose Wet, Wind Slabs and Persistent Slabs.

Avalanche Canada shorton, Avalanche Canada

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Warm temperatures and sunshine will elevate avalanche conditions across the region. Stick to low angle shaded terrain. Conditions in the northern end of the region (e.g. Clemina) are extra concerning due to a weaker snowpack structure.

Summary

Confidence

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

A ridge of high pressure brings dry, warm, and sunny weather.

WEDNESDAY NIGHT: Clear skies, light south wind, treeline temperatures drop to -6 C.

THURSDAY: Sunny, moderate south wind, freezing level climbs to 2000 m with treeline temperatures around 0 C.

FRIDAY: Cloudy with some isolated flurries, moderate south wind, freezing level climbs to 1800 m with treeline temperatures around -1 C.

SATURDAY: 5-10 cm of new snow by the morning then some sunny breaks in the afternoon, light southwest wind, freezing level climbs to 1400 m with treeline temperatures around -4 C.

Avalanche Summary

On Thursday the primary concern is natural avalanches on steep sun-exposed slopes. These will most likely present as wet loose avalanches, but larger wind and persistent slab avalanches are also possible. Read the latest Forecaster Blog for concerns about the warming.

Since the weekend, avalanche activity has primarily been limited to small (size 1) wind slab and dry loose avalanches on a variety of aspects with a few isolated larger cornice and wind slabs that released naturally.

Persistent slab avalanche activity has dramatically declined in the past week, with the last reports on Feb 24 (two size 3 explosive triggered avalanches on the late January weak layer) and Feb 26 (a size 2 human triggered avalanche in a cutblock on the February facet layer). While persistent weak layers are trending towards being unreactive, the current warming trend could temporarily heighten the likelihood of avalanches. 

Snowpack Summary

Rising freezing levels and sunshine will be melting, and potentially destabilizing, snow surfaces the next few days. Higher elevations have been impacted by recent wind from the southwest, likely leaving wind slabs lurking on shaded north and east slopes.

The lower snowpack has been strengthening with reactivity on persistent weak layers on the decline. The two layers of concern have been a layer of facets that was buried in mid-February (60-100 cm deep) and a layer of surface hoar and/or crusts that was buried in late January (80-120 cm deep). The impulse of warming over the next few days will likely be the final test on these layers, as there is some uncertainty about whether they will become reactive with warming temperatures.

Terrain and Travel

  • Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
  • Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
  • The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.

Problems

Loose Wet

An icon showing Loose Wet

Wet loose avalanches are likely to release naturally on steep sun-exposed slopes.

Aspects: South East, South, South West.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

An icon showing Wind Slabs

Reactive wind slabs likely exist in steep open terrain at alpine and treeline elevations, especially on north and east aspects.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

Warming temperatures could temporarily increase the likelihood of large persistent slab avalanches. There are two potential layers of concern buried 60-120 cm deep across the region that have produced some sporadic activity over the past weeks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely

Expected Size

2 - 3.5

Valid until: Mar 4th, 2021 4:00PM

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