Avalanche Forecast

Issued: Dec 30th, 2017 4:42PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs and Persistent Slabs.

mbender, Avalanche Canada

Cariboos.

The new year will bring a more stable weather pattern along with gradually warming temperatures. Consider the potential to trigger persistent slabs as the recent storm snow starts to finally settle and consolidate more rapidly.

Summary

Confidence

Moderate - Freezing levels are uncertain on Monday

Weather Forecast

SUNDAY: Mix of sun and cloud / Light west wind / Alpine temperature -13 MONDAY: Mix of sun and cloud / Light to moderate west wind / Alpine temperature -5 TUESDAY: Mix of sun and cloud / Moderate northwest wind / Alpine temperature -2, possible temperature inversion

Avalanche Summary

Recent reports are of a few wind slab avalanche to size 1.5 and loose dry avalanches running in steep terrain. Some cracking and whumpfing has been reported in terrain 1500m and below. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

10-25cm of low density new snow has buried a recently formed layer of weak feathery surface hoar and/or sugary facets. A layer buried mid-December that consists of surface hoar, sun crust and/or sugary facets is now down approximately 30-50cm. The bond at this old snow interface is of critical importance in areas where the overlying snow has consolidated into a slab. The most concerning areas are those that saw pronounced surface hoar development before the storm, such as sheltered areas at and below treeline, sheltered northerly aspects in the alpine, or anywhere the surface hoar formed on top of a sun crust. Recent snowpack tests show wide ranging reactivity on this weak layer. A crust which was formed by rain in late November is another major feature in the snowpack and is down approximately 70-100cm at tree line elevations. This interface has shown some signs of reactivity limited to steep, variably loaded alpine features in the adjacent North Columbia region.

Problems

Wind Slabs

Recent shifting winds have been redistributing loose snow into wind slabs on a variety of aspects.

Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Persistent Slabs

A weak layer of surface hoar buried 30-50 cm deep has potential to be reactive where the overlying snow has settled into a cohesive slab.

Buried surface hoar is more likely to be preserved in sheltered openings at and below tree line.Watch for signs of slab formation at lower elevations, such as whumphing or shooting cracks.Sluffs may trigger deeper instabilities.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 31st, 2017 2:00PM