North Columbia

6am update: New snow may be poorly bonded to old surfaces. Expect loose dry sluffing and storm slabs to slide easily. Be mindful a buried weak layer may remain triggerable.

• Closely monitor how the new snow is bonding to the old surface.
• Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
• Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

A few small (size 1) wind slab and dry loose avalanches were triggered by riders and explosives on Tuesday. With incoming snow and wind, small avalanches in the surface snow will likely continue.

The last reported persistent slab avalanche on the buried surface hoar was last Saturday. Triggering a persistent slab avalanche remains possible in upper treeline and alpine terrain.

New snow is gradually accumulating over crusts, surface hoar, and facets. Amounts on this interface vary from 5 to 30 cm, and reports suggest it may be bonding poorly.

A crust formed by a December rain event is found roughly 60 cm deep, and a layer of surface hoar is found 60 to 100 cm deep. Where it exists, the crust makes it harder to trigger the surface hoar layer, but triggering remains a concern at higher elevations where the crust is less prominent.

The lower snowpack is variable throughout the region, with basal facets possible in shallower snowpack areas.

Thursday night

Cloudy with 3 to 8 cm of new snow, alpine wind southwest 40 km/h, treeline temperature -7 °C.

Friday

Mostly cloudy with up to 5 cm of new snow, alpine wind southwest 40 km/h, treeline temperature -4 °C.

Saturday

Cloudy with 5 to 15 cm of new snow, alpine wind southwest 35 km/h, treeline temperature -5 °C.

Sunday

Mostly cloudy with a trace of new snow, alpine wind northwest 20 km/h, treeline temperature -6 °C.

More details can be found in the Mountain Weather Forecast.