Avalanche Forecast

Issued: Mar 26th, 2015 8:07AM

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

Parks Canada percy woods, Parks Canada

The upper snowpack is touchy, complex and sensitive to human triggering.  Warm temperatures are on route with wet and windy weather for the next 48hrs.

Summary

Weather Forecast

Wet flurries, rising temperatures and moderate SW winds are forecast for today, perfect for rising avalanche danger as the load increases over weak layers. Freezing levels are expected to rise to 2700m with 5mm of rain on Friday.  Alpine temperatures are expected to stay above freezing Thursday afternoon through Friday with wind gusting up to 80km.

Snowpack Summary

We have 60cm of storm snow at and above treeline and it is settling into a surface slab.  Below the surface slab are a sandwich of crusts, surface hoar and facetted layers that are building reactivity to light loads such as skiers.  A weak facet layer on top of a crust down 70cm is easily triggered at treeline and is prone to propagation.

Avalanche Summary

Additional load and warming temperatures will increase the sensitivity of the weak layers in the upper snowpack.  Convex rolls are reactive to ski cuts triggering slabs on the weak facet layer on top of crust combo.  Loose snow sluffing out of steep terrain has also been enough load to trigger this layer. 

Confidence

Problems

Persistent Slabs

An icon showing Persistent Slabs
Persistent weak layers down 50-100cm have been triggered recently by light loads such as skiers and sluffing from steep terrain.  These layers have been remotely triggered and are prone to propagate widely.
Be alert to conditions that change with elevation.Choose conservative lines and watch for clues of instability.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Storm Slabs

An icon showing Storm Slabs
The building load of storm snow is settling into a surface slab and is bonding poorly where it overlies a crust.  S through SW winds are creating pockets of fresh windslab at ridge top. Rising temps will increase reactivity of the storm slab.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Mar 27th, 2015 8:00AM