Avalanche Forecast
Issued: Apr 14th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Loose Wet and Deep Persistent Slabs.
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Avalanche Canada
Two things to watch out for: at lower elevations loose wet avalanches during the heat of the day, often running on a crust and going faster & bigger than one might think; at upper elevations, especially on southerly aspects where the dry snow sits on a crust, storm slabs have been propagating widely, are surprisingly deep, and could be triggered by warmth, cornices, or riders.
Summary
Confidence
Avalanche Summary
A serious avalanche incident occurred in the backcountry just east of Revelstoke on Wednesday. Details are available here. This is representative of the recent storm snow above a crust problem.
Thursday's avalanche reports spoke to the continued storm slab or persistent slab avalanche problem (previous dry snow above crusts or facets from April 7 or March 31) with several avalanches to size 3.5, many seemed to release with daytime warming. Some were cornice triggered.
Looking forward, the need for backcountry travelers to manage a wide range of avalanche concerns that vary by elevation and aspect continues.
Snowpack Summary
High elevations (where winter remains and the snow is dry) around 30-60 cm, (even deeper on the west side of the Purcells near the Bugaboos). And of course previous storm snow is also deeper on lee features
All this snow overlies either a widespread melt-freeze crust buried April 7, a weak interface of faceted snow and surface hoar buried at the end of March, or some combination of the two. Both of these interfaces can serve as weak layers; numerous recent avalanches, some with wide propagation, are attributed to each.
The mid-snowpack is strong. However, November depth hoar remains at the base of the snowpack and remains a concern in rocky, shallow, variable depth snowpack areas at treeline and above.
Weather Summary
Friday Night
Clear periods. Nil precipitation. Increasing southwest winds gusting to moderate. Treeline temperatures around -7 with freezing level at valley bottom..
Saturday
Cloudy with sunny periods and isolated flurries. WInd from the south or southwest, light to moderate. Alpine high temperatures around -5 C with freezing levels to 1900 m.
Sunday
Warm overnight with freezing level only falling to around 1400m. Sunday itself overcast with 5 to 15 cm of snow (lightest amounts in the north, highest amounts in the south). Alpine temperatures around -3 C with freezing level up to around 1900 m. Light, gusting moderate southerly wind.
Monday
Mix of sun and cloud with isolated flurries. Only a trace of precipitation. Cooler with diminishing wind. Freezing level around 1700 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Stay in tune with the physical environment, conditions may change throughout the day.
- If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Storm Slabs
The recent snow hasn't yet bonded to the lingering interfaces from late March and early April. This snow is being triggered by day time warming, failing cornices, or riders, and it's propagating widely.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Surface snow will destabilize and may avalanche naturally with daytime warming and especially with solar exposure.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth.
Suspect terrain includes steep, shallow, and rocky terrain where the snowpack varies beween thin and thick.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 15th, 2023 4:00PM
