Avalanche Forecast

Issued: Feb 23rd, 2017 4:32PM

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

Avalanche Canada shorton, Avalanche Canada

Choose supported terrain and watch for shallow snowpack areas where triggering a large persistent slab avalanche remains possible.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

We're into a stable and benign weather pattern with cooling temperatures and isolated flurries.FRIDAY: Cloudy with sunny periods, light winds, alpine temperatures around -14 C.SATURDAY: Flurries starting in the afternoon with accumulations of 2-4 cm, light west winds, alpine temperatures around -14 C.SUNDAY: Flurries with trace amounts in the north and up to 10 cm in the south, light southeast winds, alpine temperatures around -12 C.

Avalanche Summary

On Thursday, a few small loose dry avalanches were reported in steep terrain., On Wednesday, as few size 1 skier triggered slabs were reported in unsupported alpine terrain and a few older size 1-2 storm slabs were reported on northerly aspects. Earlier in the week, there were several large skier triggered avalanches, including a remotely triggered size 2 wind slab near Kimberly, a skier-triggered size 2.5 persistent slab near Golden, and a remotely-triggered size 3 persistent slab near Golden. See here for a MIN report from one of the large avalanches near Golden.Small avalanches in the new storm snow remain the primary concern on Friday, but remember they have the potential to step down and trigger persistent slab avalanches.

Snowpack Summary

Light flurries over the past few days have delivered 10-25 cm of low density snow. Expect to find isolated pockets with thicker wind deposits at higher elevations as well as sun crusts forming on steep south-facing slopes. The recent snow has buried the mid-February interface, which is composed of a thick rain crust up to about 2000 m, sun crusts on steep solar aspects, and spotty surface hoar on shaded aspects. Storm snow from previous weeks is still bonding poorly to the February 3rd surface hoar / sun crust layer, which is now down 60-80 cm. A persistent weakness buried mid January is about a metre deep and the November crust is about 1.5 metres deep. These deep persistent weaknesses still have the potential to wake up and become reactive with human triggers. (See MIN post above).

Problems

Storm Slabs

An icon showing Storm Slabs
The fresh snow may still be reactive in isolated areas, particularly on wind-loaded slopes.
Avoid freshly wind loaded features.Use caution above cliffs where small avalanches may have severe consequences.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
A persistent weak layer of surface hoar and facets down 60-80 cm remains a concern in isolated areas. Smaller avalanches have the potential to step down to this and deeper persistent weaknesses, resulting large avalanches.
Use conservative route selection, choose moderate angled and supported terrain with low consequence.Whumpfing, shooting cracks and recent avalanches are all strong indicators of unstable snowpack.Be aware of the potential for large avalanches due to the presence of deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Feb 24th, 2017 2:00PM