Avalanche Forecast

Moderate - Uncertainty is due to whether buried persistent weak layers become active, triggering avalanches, with the arrival of the forecast weather. Forecast snowfall amounts are uncertain.

An arctic front gradually pushes its way South bringing cold air and some light embedded flurries. A cold northwest wind will persist through the forecast period.

Saturday: Cloudy with flurries 5-10 cm. Alpine temperatures near -5 and light wind from the West.

Sunday: Mix of sun and cloud. Alpine temperatures near -15 with moderate ridgetop wind from the northwest.

Monday: A mix of sun and cloud. Alpine temperatures near -25 and mostly light wind from the northeast. 

 

On Friday, numerous loose-dry avalanches were reported up to size 2 during the storm in steep terrain. 

On Thursday, reports indicated several small features were reactive up to size 1 on the late-January buried surface hoar interface. I suspect that once the persistent slab gains more cohesion and stiffens, this problem may be more widespread. Even a small avalanche can catch you by surprise and have enough mass to push you into a terrain trap below. 

Fresh storm slabs may be touchy on Saturday, especially where they sit above surface hoar, crust, or old surface facets. 

Up to 30 cm of recent low-density snow fell by Friday bringing 40-80 cm of accumulative storm snow from the past week over a variety of older snow surfaces. These old surfaces, at upper elevations (upper treeline and the alpine), include surface hoar in locations sheltered from the wind, surface facets, and stiff wind affected snow. At lower elevations (lower treeline and below treeline) 10-30 cm of snow sits above isolated pockets of surface hoar and a crust that is more predominant on solar aspects. 

Additional snow and changing wind combined with cohesion may stress these potentially weak interfaces, creating the persistent slab problem. This MIN from last weekend is a good example: MIN Report.

The mid-pack seems to be well settled. Deep persistent layers appear to have mostly gone inactive with the exception of the Bear Pass area and the far reaches south of Kitimat. 

• Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
• Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
• Watch your sluff: it may run faster and further than you expect.
• Pay attention to cornices and give them a wide berth when traveling on or below ridges.