An unusual weather pattern could bring heavy snowfall and push us past the tipping point for large natural avalanches. Stick to simple terrain and avoid overhead hazards.
Summary
Confidence
Low - Forecast snowfall amounts are uncertain
Weather Forecast
Clashing fronts make for difficult forecasting the next few days. A Pacific warm front and an Arctic cold front are converging over the Rockies, creating the potential for some surprise accumulations of low density snow. Timing, location, and intensity are highly uncertain and so are the estimate snowfall amounts.SATURDAY: Flurries starting Friday night with accumulations of 10-25 cm possible by Saturday afternoon, strong northwest wind, cooling throughout the day with alpine high temperatures around -5 C.SUNDAY: Cloudy in the morning with snow resuming in the afternoon, heavy accumulations possible into Sunday evening (10-30 cm?), strong west wind, alpine high temperatures around -10 C.MONDAY: Cloudy with isolated flurries, light wind, alpine high temperatures around -10 C.
Avalanche Summary
A few small wind slabs were triggered in lee terrain by skiers on Thursday and Friday as storm snow accumulated. The slabs occurred in the top 20 cm of new snow. A few natural wind slabs up to size 2 were also reported throughout the region.A few large persistent slab avalanches that released during last weekend's storm were observed this week. These avalanches failed on deep weak layers from November and December, resulting in large avalanches (size 3). Most were triggered by cornices falling on north and east facing slopes. The incoming storm has potential to trigger similar large avalanches, especially given with strong winds in the forecast.
Snowpack Summary
Expect waves of fresh snow over the next few days as storm snow accumulates. The distribution will be spotty, as some areas already have 30 cm and others nothing. Stay aware of the condition of the new snow. Mostly low density powder is expected, but could become heavy if it warms up. Strong winds will promote slab development in exposed terrain.The lower snowpack in this region is weak, with a number of concerning weak layers. A layer buried mid-January is composed of surface hoar on sheltered aspects and a sun crust on solar aspects was and is now 30-50 cm deep. Another surface hoar layer from early-January is buried 40-60 cm deep. A widespread weak layer from mid-December composed of facets, crusts, and surface hoar is 60-80 cm deep. Finally, a rain crust with sugary facets buried in late-November is near the bottom of the snowpack. Although the snowpack structure is variable across the region, these persistent weak layers are generally widespread.
shorton,
Avalanche Canada
