Avalanche Forecast

A ridge of high pressure weakens as a trough of low pressure passes to the south of the Caribous. Temperatures remain cold with a mix of sun and cloud to the north and mostly cloudy conditions to the south with no notable precipitation.  

FRIDAY NIGHT: cloudy with clear periods, light Northwesterly wind, low temperatures around -11 C. 

SATURDAY: A mix of sun and clouds, light to moderate Southeasterly wind, high temperatures around -7 C. Freezing Level Valley bottom.  

SUNDAY: Cloudy with sunny periods and isolated flurries, moderate South/Southwesterly winds, high temperatures around -6 C. Freezing Level Valley bottom. A mild Alpine temperature inversion may produce valley clouds and cool temps with clear skies and a bit warmer above.

MONDAY: Mainly cloudy with isolated flurries, moderate to strong Southwesterly winds, High temperatures -8C. Freezing Level Valley rising to 1)00m. 

Evidence of the recent avalanche cycle in the Middle and South More Rivers region during the peak of this week's storm including photos can be seen in this MIN by the North Columbia (& Cariboos) field team. They observed numerous large and very large avalanches that ran to valley bottom. Another MIN from Dec 11 also reports evidence of natural avalanches during this recent cycle. This is consistent with reports from the nearby North Columbia where a series of large and very large avalanches were observed at the peak of the storm. 

As the weather remains cold and with no new snow, the recent snow will continue to gain strength and bond to old interfaces. Nonetheless, the recent 15-40cm (more to the mountainous south) sits atop a weak layer of surface hoar in wind-sheltered areas at treeline and at upper below treeline elevations (above the extent of the rain crust estimated at 1500m). We will have to keep investigating this Surface Hoar, especially if any storm slab or wind slabs overlie it.  

Wind slabs likely linger in higher wind-affected terrain. Steep solar terrain has likely had some natural avalanche activity with recent sun.  

With little in terms of field observations, a cautious and conservative approach to terrain is needed. Be aware of these new avalanche problems by looking for signs of instability like shooting cracks and whumpfs. Furthermore, an avalanche triggered in the upper snowpack could cause a larger deep persistent slab avalanche.

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).

The combination of a warm storm earlier this week followed by cooler temperatures has reworked the snowpack. Heavy rain was reported up to 1500 m, so lower elevations will now have a thick surface crust or "dust on crust". 15-40 cm of snow fell at higher elevations, with the largest accumulations around Valemount and Blue River.  

The most concerning part of the snowpack remains how well this new 15-40 cm of snow is bonding to a widespread buried surface hoar layer (or above sun crusts). Thus far minimal slab properties have developed, but exposed areas at ridge crests may see some soft wind slab formation. Carefully assess steep open slopes at intermediate elevations if you see slab properties in the snow (just above, at and below tree line). In other words - that zone of lower alpine terrain but above the rain line - could be holding the most dangerous problem: a storm slab over surface hoar or sun crust, especially where winds have helped create a slab.

In the alpine this snow has formed thick wind slabs, which should generally be strengthening quickly.  

As ever, assess how direct sun is affecting steep solar terrain and anticipate stuffing or loose snow avalanches when transitioning into steeper terrain.

Down near the ground remains a thick rain crust with sugary facets above and below from early November rains (Nov 5 Crust). While we have not seen much reactivity on this layer, it continues to produce occasional Hard results in snow tests. It is most likely to be reactive to human triggers on shallow rocky slopes in the alpine or tee line "alpine-like" features or be triggered by a step down avalanche.

Check out this MIN from Dec. 10 in the Allen Creek that report intact Surface Hoar at 1500m (just above the rain line) and a higher test result at 2100m on this deep Nov 5 crust.

This MIN & MIN from Dec 8 mention stormy conditions, won observations & some great photos. And this MIN from the same day tells the story of warm wet conditions (that are now refrozen down low).

• Investigate the bond of the recent snow before committing to your line.
• Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
• Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
• Be aware of the potential for large avalanches due to the presence of a deep persistent slab.