Avalanche Forecast

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

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 -12 and light wind from the southeast.

Sunday: Mix of sun and cloud. Alpine temperatures near -20 with light ridgetop wind from the northwest.

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

On Thursday a MIN report from the Seaton South Ridge triggered a size 1 wind slab on a north aspect at treeline. The report said that the bed surface had a few cm's of soft snow possibly surface hoar above a somewhat icy crust. The slab was small but ran fast on the bed surface. Awesome report! Thanks for sharing this information. I suspect that once this new low-density storm snow forms more of a slab, conditions may increase in reactivity and hazard. Skier and rider triggering is likely. 

 

Up to 10-25 cm of new snow fell by Friday bringing 25-50 cm of accumulative low-density storm snow from the past week over a variety of old snow surfaces. These old surfaces include surface hoar in locations sheltered from the wind at all elevations, surface facets, and stiff wind affected snow. On solar aspects, a buried sun crust can be found and a thick crust exists near the surface below 1000 m. Additional snow and changing wind combined with cohesion may stress these potentially weak interfaces, creating the persistent slab problem.

The lower snowpack has two decomposing crust layers. The upper crust is 70-140 cm deep and continues to show occasional hard sudden results in snow pits. The deeper crust at the bottom of the snowpack is more prevalent in shallow snowpack ranges. These deep persistent layers seem to be dormant under the current conditions, but shallow rocky slopes should still be carefully assessed and approached with caution. 

• 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.
• Watch for changing conditions today, storm slabs may become increasingly reactive.