Avalanche Forecast

Issued: Feb 20th, 2015 7:40AM

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

Avalanche Canada Peter, Avalanche Canada

Watch for deep and touchy pockets of wind slab in wind exposed terrain.

Summary

Confidence

Good

Weather Forecast

The ridge of high pressure rebuilds and should result in clearing skies in most parts of the Province. However, there is a weak cold front sliding in from the east that could bring cloud and light snow to parts of the Southern Interior (particularly the east side of Purcells). By Sunday all regions should be enjoying sunny skies. The freezing level on Saturday is 500-1000 m and it bumps up a couple hundred metres each day. Ridge winds are light gusting to moderate from the NW to NE.

Avalanche Summary

Avalanche activity has gradually tapered off throughout the week. On Thursday explosive control work on steep North and East facing slopes only resulted in loose snow sluffs. Earlier in the week there were reports of natural and explosive triggered cornice falls and slabs, typically size 2-3 and all from alpine terrain.

Snowpack Summary

A light dusting of new snow covers the previous variable snow surface of crusts, surface hoar, dry facetted snow, or wind affected snow depending on aspect and elevation. Thin new wind slabs are likely in exposed lee terrain, and cornices remain large and weak. The 'Valentine's Day' crust is thick and supportive below 2100 m. The late-Jan crust/surface hoar layer is 1-2 m deep in the west, and can be found within the upper metre of the snowpack further east. It is variably reactive in snowpack tests and still the main concern in many areas. The mid-January surface hoar, deeper again, remains problematic in some areas. The mid-December and mid-November weak layers of crusts and facets can still be found near the bottom of the snowpack, particularly in shallower eastern parts of the Purcells.

Problems

Wind Slabs

An icon showing Wind Slabs
Pockets of touchy wind slab may still be sensitive to triggering in lee and cross-loaded terrain. Some areas could see these slabs build if there is a decent amount of snow on Saturday with moderate winds. 
Give cornices a wide berth when travelling on or below ridges.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Buried persistent weaknesses are largely dormant but could still be triggered by a large load (i.e. cornice fall) or from areas with a shallow or variable snowpack.
Do not travel on slopes that are exposed to cornices overhead.>Avoid common trigger points like convexities or areas with a thin or variable snowpack.>

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Feb 21st, 2015 2:00PM