North Columbia

It's still winter out there; as the snowpack slowly transitions to spring, riders need to manage a wide range of avalanche concerns that vary by elevation and aspect. Continually assess conditions as you travel and adjust objectives, terrain choices, and travel techniques to match your local conditions.

A fatal avalanche occurred on April 15 in the Thunderwater Lake riding area. The size 3 (very large) avalanche was triggered near a rocky area. Two riders were caught, one was buried approximately 2 meters deep and did not survive. Any additional information we have available can be found in this MIN.

Over the weekend a number of natural and explosive-controlled avalanches occurred on persistent weak layers. 1 explosive triggered size 3 avalanche slid on basal facets.

Also on Saturday, were a pair of size 2.5 Loose Wet and Persistent slab avalanche in Glacier National Park.

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 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.

It's still winter out there; as the snowpack slowly transitions to spring, riders need to manage a wide range of avalanche concerns that vary by elevation and aspect.

At higher elevations, the recent storm snow remains dry (at least on shady terrain). While melt-freeze crusts and/or moist snow are likely to be found on steep solar slopes and at lower elevations.

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, the 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.

Monday night

Mostly clear, with cloudy periods. Light southeast ridgetop winds. Treeline temperatures around -5 C.

Tuesday

Cloudy with afternoon flurries and a trace of snow. Light south ridgetop winds. Treeline temperatures 0 to -5 C. Freezing level 1600 m.

Wednesday

Cloudy with scattered flurries and a trace of snow in localized areas. Light west ridgetop winds. Treeline temperatures around -5 C. Freezing level 1600 m.

Thursday

Cloudy with scattered flurries and a trace of snow in localized areas. Light west ridgetop winds. Treeline temperatures 0 to -5 C. Freezing level 1900 m.

More details can be found in the Mountain Weather Forecast.

• Be alert to conditions that change with elevation and sun exposure.
• 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.