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Avalanche Forecast

Archived

Dec 18th, 2018–Dec 19th, 2018

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Northwest Inland.

We're lacking information about recent avalanche activity, so it's critical to make your own observations. Back off if you see recent avalanches, cracking, or whumpfing.

Confidence

Low - Due to the number of field observations

Weather Forecast

TUESDAY NIGHT: Flurries with localized accumulations of 3-8 cm, strong wind from the southwest, freezing level dropping to valley bottom, alpine temperatures drop to -8 C.WEDNESDAY: Mostly cloudy with isolated flurries, moderate wind from the southwest, alpine temperatures steady around -8 C.THURSDAY: Scattered flurries with up to 5 cm of snow, light to moderate wind, alpine high temperatures around -8 C.FRIDAY: Mostly cloudy with isolated flurries, moderate wind from the west, alpine high temperatures around -8 C.

Avalanche Summary

On Sunday, recent slab avalanches, whumpfing, and cracking were observed in the Hankin area. See this MIN report. Natural slab avalanches were also reported last week during the start of the stormy weather, including two large avalanches (size 2) on east-facing wind-loaded slopes near treeline (1700 m) and several smaller slabs in steep gullies at low elevations. See this MIN report from Ashman. Recent avalanches have probably failed in the storm snow and possibly on a weak layer from the early December dry spell found roughly 40-70 cm below the surface.

Snowpack Summary

A total of 40-70 cm of snow has fallen over the past week, likely forming storm slabs and wind slabs throughout the region. The combination of new snow and strong wind from the southwest is likely forming thicker and more sensitive wind deposits at higher elevations. The storm snow may still need a bit more time to form a good bond with the weak surface hoar and facets that formed during the dry spell in early December. We're lacking information about the current strength of this potential weak layer. Deeper in the snowpack, there are several crusts including an early season crust with facets near the bottom of the snowpack.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.