Avalanche Forecast

Friday night: Cloudy with isolated flurries and a trace new snow. Moderate west winds, easing into the morning.

Saturday: Cloudy with a chance of isolated flurries, increasing overnight. Light to moderate southwest winds, increasing in the evening. Alpine high temperatures around -7.

Sunday: Cloudy with scattered flurries continuing from the overnight period and 10-15 cm of new snow, easing over the day. Moderate to strong southwest winds shifting west. Alpine high temperatures around -7 with freezing levels rising to 1000 metres.

Monday: A mix of sun and cloud. Light northwest winds shifting southwest and increasing overnight. Alpine high temperatures around -9.

We're still light on field observations from the aftermath of Tuesday's storm, however it it's safe to assume it's been a busy couple of days for natural avalanches, with up to 40 cm of new snow blanketing the region and subsequently being redistributed by strong winds. Activity was likely less pronounced in the north of the region, which saw closer to 15 cm of new snow.

Observations from the neighbouring North Columbias may serve to illustrate the kind of activity that likely took place in southern parts of the region on Tuesday and Wednesday. Here, observations show many storm and wind slab releases generally in the size 1.5-2.5 range with several reaching up to size 3. In the Trans-Canada corridor, a size 4 (VERY LARGE) avalanche ran on Mt. Laurie.

Persistent slab releases have not figured too prominently in reports thus far, but observations are still limited and the few that have been reported are notable. Check out these MIN reports from the Dore River and the Gorge (near Revelstoke) for an example of the isolated deep releases we're concerned about.

Looking forward to Saturday, it remains a good idea to give recently formed wind slabs a wide berth as you approach wind affected terrain, and to remain suspicious of steeper sheltered slopes where storm snow may have slabbed up over a layer of surface hoar or crust. Using small test slopes to investigate the bond of the storm snow is a good plan, but be cautious about extending your observations to more committing terrain.

Since field observations in this region are limited, please consider submitting your observations to the Mountain Information Network. 

15-40 cm of snow fell in the region during Tuesday's storm, with accumulations greatly favouring the south of the region. This buried wind affected surfaces at upper elevations, as well as surface hoar in wind sheltered areas and a thin crust on solar aspects. In exposed areas, recent elevated winds have been redistributing new snow into reactive wind slabs and adding to cornices.

In most places, the storm snow is probably forming a good bond with the previous surface. Exceptions are likely in areas harbouring surface hoar. Think of shaded upper below treeline and lower treeline areas, above where surface crust exists and below more wind-affected elevations. It's mainly in the south of the region where enough storm snow sits above this layer to pose a real threat.

A couple of older persistent weak layers exist in the mid, down about 70-120 cm. The distribution of these layers are variable, but follows a similar pattern to the layer discussed above. The upper layer is spotty surface hoar at shaded treeline and below and the lower layer may present as decomposing surface hoar and/or a crust. It was most prevalent in areas near Valemount. 

Avalanche activity on these deeper layers has dwindled since the last storm, with snowpack tests giving increasingly resistant results, but still showing some propagation. Given their age (particularly the deeper layer) and the testing load brought by Tuesday's storm, the outlook is good for these layers to finally become dormant as our current surface instabilities diminish.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
• When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.