Avalanche Forecast

Issued: Dec 18th, 2018 5:46PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs and Persistent Slabs.

shorton, Avalanche Canada

Lizard-Flathead.

Recent snowfall has stressed the snowpack, leaving it primed for human triggered avalanches. Conservative terrain choices are recommended.

Summary

Confidence

Moderate -

Weather Forecast

TUESDAY NIGHT: Lingering flurries could produce another 10cm of snow, strong wind out of the southwest, freezing level dropping to 1000m, alpine temperatures drop to -5c. WEDNESDAY: Flurries easing throughout the day with localized accumulations of 5cm, moderate wind from the southwest with strong gusts, freezing level up to 1200m, alpine high temperatures around -5c. THURSDAY: The next system arrives late in the day, strong wind from the southwest, freezing level climbs to 1500m, alpine high temperatures around -2c. FRIDAY: 10-20cm of snow, moderate wind from the northwest, freezing level drops to valley bottom with alpine high temperatures around -8c.

Avalanche Summary

Tuesday's storm produced natural storm slab avalanches in alpine terrain and numerous small skier triggered avalanches (size 1) on small steep slopes.On Saturday, a group of skiers remotely triggered a large (size 2) avalanche on a northeast facing slope at treeline in the Corbin area. The skiers were in dense trees and the avalanche released roughly 60 m above them. One skier was fully buried and the group successfully extricated them without significant injuries. For full MIN incident report follow this link.

Snowpack Summary

Tuesday's storm hit the region with 40 cm of new snow, forming fresh storm slabs at upper elevations. The precipitation fell as rain below 1500 m, leaving moist snow on the surface.Roughly 50-80 cm of snow now sits above a weak layer composed of large surface hoar, facets, and/or sun crusts. There have been numerous signs over the past few days that this layer remains weak (e.g. remote triggering from low angle terrain, wide propagations in avalanches), and the additional load of the new snow could be pushing this layer past the tipping point.Several other weak layers have been observed in the lower snowpack such as early season crusts with weak facets. The most concerning crust is prevalent at higher elevations and is likely most problematic on north-facing features, especially those that are large and planar in nature.

Problems

Storm Slabs

40 cm of new snow has left storm slabs primed for human triggering, especially on steep and wind loaded slopes.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

A widespread weak layer is being stressed by the new snow and has the potential to produce large destructive avalanches.

Avoid areas with overhead hazard.Remote triggering is a concern, watch out for adjacent slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Dec 19th, 2018 2:00PM