Avalanche Forecast

Issued: Apr 15th, 2023 4:00PM

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

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At upper elevations, especially on east, south, or west 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. Reports of whumpfing from the west side of the Purcells are noteworthy and worrisome!




Avalanche Summary

Friday's reports show the weak layers, up to 80 cm below the surface, were reactive to explosives, skiers, and naturally. Sizes were between 2 and 3.5. Additionally, there are stories about whumpfing around moraines. Explosives targetting the deep persistent layer at the bottom of the snowpack with released several size 3.5 avalanches up to 200 cm thick.

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.

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.

Looking forward, the need for backcountry travelers to manage a wide range of avalanche concerns that vary by elevation and aspect continues.

Snowpack Summary

At the surface crusts have formed on solar aspects and surface hoar is growing on shady aspects. At high elevations (where winter remains and the snow is dry) around 30-60 cm of previous storm snow is settling and remains dry (at least on shady terrain).

Recent snow overlies two lingering weak layers: a widespread melt-freeze crust buried April 7 and a layer of faceted snow or surface hoar buried April 1. Whumpfs and numerous recent avalanches, some with wide propagation, are attributed to these lingering problem layers.

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

Saturday Night

Cloudy with clear periods and isolated flurries. Only a trace of new snow. Freezing level falling to around 1200 m. Light to moderate south wind.


Cloudy with sunny periods and showers during the day. New snow around 2 - 5 cm but possibly as much as 10 cm south of Revelstoke. Freezing level around 2100 m. Light to moderate southwest wind. Treeline temperatures around 0 C. Snow picks up after the sun sets with up to 15 or 20 cm of snow (favoured areas are south of Revelstoke and the west side of the Purcell Mountains) by Monday morning.


Cloudy with sunny periods and an additional 2 to 5 cm accumulating. Again, highest accumulations in the south. Freezing level around 1700 m and treeline temperatures around -5 to -10 C. Light to moderate westerly winds.


A mix of sun and cloud with flurries. A trace to 5 cm of new snow. Freezing level around 1700 m and treeline temperatures around -3 to - 8 C. Light southwest winds.

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.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.


Storm Slabs

An icon showing Storm Slabs

Reports of whumpfing are noteworthy; the snow remains sensitive and it seems remotely triggered avalanches are possible. This snow is being triggered by day time warming, failing cornices, or riders, and it's propagating widely.

Aspects: All aspects.

Elevations: Alpine, Treeline.



Expected Size

1.5 - 2.5

Deep Persistent Slabs

An icon showing 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.



Expected Size

2.5 - 3.5

Loose Wet

An icon showing Loose Wet

Surface snow will destabilize and may avalanche naturally with daytime warming and especially with solar exposure.

Aspects: South East, South, South West.

Elevations: All elevations.



Expected Size

1 - 2

Valid until: Apr 16th, 2023 4:00PM