Avalanche Forecast

MONDAY NIGHT: Freezing level at valley bottom, light northwest wind, trace of snow possible. 

TUESDAY: Overcast, freezing level rising to 500 m, moderate west/northwest wind, a few cm of snow in the north with up to 15 cm possible around the Coquihalla.

WEDNESDAY: Scattered cloud cover at dawn clearing throughout the day, freezing level topping out around 800 m, light northwest wind, no significant precipitation expected.  

THURSDAY: Scattered clouds at dawn building to overcast in the afternoon, freezing level topping out at 600 m, rising to about 1500 m in the afternoon, strong south wind expected Thursday afternoon, no snow anticipated during the day. 5 to 10 mm of precipitation Thursday night with a freezing level around 1000 m. 

On Sunday a size 3 natural avalanche was observed on a southwest facing alpine feature in the north of the region. MIN reports from Sunday detail a lot of good skiing in wind sheltered terrain.

Recent wind slab formations are widespread in the region, with small (size 1.5) wind slabs triggered with ski cutting on wind loaded slopes in the Coquihalla on Friday and Saturday. Check out this MIN report for a great example of layered/obscured wind slabs reactive to skier triggering in the south of the region. Another MIN detailing an avalanche involvement in the north of the region gives a clear picture of hazards perched on alpine features.

A notable size 3 (very large) persistent slab was remotely triggered (from a distance) by a group of skiers in the McGillivray Pass February 8th. This occurred on a southwest aspect at 2400 metres. It was described as a hard wind slab formed over our facet layer from late January.

5 to 10 cm of new snow fell across the region with light southeast wind Sunday night into Monday. This snow comes to rest on faceted grains fromed during the recent cold temperatures. Just under Monday's snow there is 20 cm (north of the region) to 60 cm (south of the region) of low density snow in sheltered areas, along with more widespread wind-affected surfaces. 

Previous to Monday's snow, region-wide northeast winds formed many new wind slabs across exposed higher elevation terrain. Winds have not been consistent, so don’t be surprised to find reactive, potentially layered or buried slabs on a wide range of aspects as you approach wind-exposed terrain.

On solar aspects, a thin recent sun crust may be found on or right near the surface or beneath recently wind transported snow, potentially contributing to the reactivity of new slabs on sun-exposed aspects.

Persistent weak layers of concern below this storm snow vary by location in the region. In the south, the primary feature, found at treeline and below in the Allison Pass area, is a melt-freeze crust from mid-January, about 50 cm deep. Although this layer is present (twice as deep) in the Coquihalla snowpack, no persistent weak layers are currently considered problematic in that area.

In the north, many of the recent wind slab formations discussed above have been reactive to skier triggering on early February interfaces of surface hoar (think shaded aspects), and may also exist over a thin sun crust from the same period (think solar aspects). Another older (January 24), slightly deeper, widespread layer of faceted snow remains a concern in shallow or variable snowpack depth locations in the alpine. 

Also In the north, a melt-freeze crust from early December may be found 100 to 200 cm deep. Recent reports have suggested that this layer is unreactive and gaining strength, however ongoing cold temperatures may currently be weakening the snow around it in thin snowpack areas.

• Avoid freshly wind loaded terrain features.
• Watch for fresh storm slabs building throughout the day.
• Watch for areas of hard wind slab on alpine features.
• Be aware of highly variable recent wind loading patterns.