Avalanche Forecast

Moderate - Uncertainty is due to field data and reports showing a wide variation in conditions throughout the region. Uncertainty is due to the limited number of field observations.

A mix of sun, clouds and snow flurries for the next few days as a high pressure shifts to the east and the next low pressure moves in Sunday.  

Thursday Night: Mostly cloudy with clear skies to the north, light and variable wind, freezing level 600m. Alpine Low -6C.

Friday: Cloudy with scattered flurries to the south (up to 5cm new snow) with a mix of sun and clouds in the north, light and variable winds, freezing level 800 m. Alpine Low -10C / High -6C

Saturday: A mix of sun and clouds with isolated fluries, light Southerly winds, freezing level 700 m. Alpine Low -10C / High -7C

Sunday: Cloudy with snow flurries, AccumulationsTrace to 8cm (less to the north), light-moderate Southerly winds, freezing level 700 m. Alpine Low -10C / High -7C.

Avalanche hazard is highly variable and dependent on snowfall amounts and freezing lines experienced locally by this recent storm. Cooler temperatures and the passing of the storm mean that the natural avalanche cycle will taper. However, reports continue to illustrate the poor bond of the new snow to buried surface hoar and rain crusts near the surface, particularly where there is more than 30cm of new snow.

Reports from Wednesday told of a few natural large avalanches below tree line and at tree line locations. Additionally, on Wednesday avalanche control work was able to trigger large avalanches on the Nov 5 rain crust deep persistent layer in northerly shallow rocky terrain around 2000m. Elsewhere, numerous reports have come in describing the poor bond of new snow to the recent rain crusts producing small to large avalanches.  

On Tuesday, at the peak of the cycle, there were reports of large avalanches (Size 2) naturally and from skier controlled and explosive control work on Tuesday. A few Very Large (Size 3) Natural avalanches were reported running to valley bottom along the highway corridor.  

Our eyes and ears in the mountains are limited this winter due to fewer professional observations. If you go out in the mountains, please share your observations on the Mountain Information Network (MIN). Photos are especially helpful! Thank you so much for all the great MINs submitted so far!

The combination of heavy snow and rains with the warm storm earlier this week followed by cooler temperatures has reworked the snowpack. This storm deposited snowfall amounts of 20-40cm that fell on widespread large surface hoar and sun crusts on steep solar.  

We knew that prior to this storm this widespread large surface hoar was going to be an issue for a while. We suspect that heavy rains have made this layer less of an issue in many lower elevation areas. However, we KNOW this layer is still preserved in many tree line and below tree line locations which were not as affected by high freezing levels and rain events. In other words, if there is no THICK rain crust at and below tree line, be on the look out for buried surface hoar. Importantly, buried surface hoar is more preserved in the North and in some places a thin rain /temperature crust caps intact crystals. 

Freezing rain with the recent storm has created a thick rain crust (or two) up to 2000m in the southern region of the forecast area. Its distribution and extent remains unclear - especially in the Northern regions - but we believe it is widespread in the southwestern portions of the region with reports of up 1- 5cm thick near tree line. In some areas there are two rain crusts: a thin crust near the base of the recent storm snow and a second thicker crust near the surface. See this MIN report from near Crowfoot Mountain & this MIN report from the South Columbia near Hall Mountain. From the far north region comes this MIN with reports of Rain up to 1500m.

In the Alpine, recent winds will have redistributed snow. These storm slabs sit atop suncrust on solar aspects.  

The most notable layer in the lower snowpack is from early November rains (Nov 5 Crust), which is now sitting near the base of the snowpack and is likely surrounded by a weak layer of sugary facets. It is most likely to be reactive to human triggers on shallow rocky slopes in the alpine.

• Investigate the bond of the recent snow before committing to your line.
• Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
• Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
• In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.