Avalanche Forecast

Issued: Mar 10th, 2014 6:17PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

Conditions are hair trigger right now. Any steep enough slope that hasn't avalanched will. It is a good time to stay out of avalanche terrain until the snowpack can adjust to the new load.

Summary

Weather Forecast

We are starting to get into some spring-like weather. Generally sunny skies, freezing levels in the 1000-1600m range and light westerly alpine winds. Winds will pick up from the NW on wed/thurs. Overnight lows will be ~ -5/-10. Watch for solar warming and its destabilizing effect on the snow as the sun is strong these days!

Snowpack Summary

85-100cm of storm snow has fallen in the Sunshine, Kootenay and Yoho areas, with 40-60cm around Lake Louise and Bow Summit since Mar 2nd. This storm snow has overloaded the Feb 10th layer of facets, surface hoar and sun crust, and in thinner snowpack areas, the deeper basal facet layer, causing large, destructive avalanches with wide propagations.

Avalanche Summary

A widespread natural avalanche cycle occurred yesterday on all aspects and elevations and continued today with warmer temperatures and solar input. Bombing today in Kootenay produced large, destructive avalanches on 29/32 shots. Additionally, 2 large skiier triggered avalanches on Mt. Fairview and West bowl show how touchy conditions are right now.

Confidence

Due to the number of field observations

Problems

Persistent Slabs

The recent snow has overloaded this layer. Although natural activity is tapering, this layer remains VERY touchy as seen by two very close calls today.

Avoid all avalanche terrain.Avoid areas with overhead hazard.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely - Certain

Expected Size

2 - 4

Deep Persistent Slabs

In thinner snowpack areas, many avalanches are initiating as a storm or persistent slab and are stepping down to this layer.

Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.Minimize exposure to sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely - Certain

Expected Size

2 - 4

Storm Slabs

The storm slab will settle over the next few days, but is currently very touchy. Most avalanches are initiating on this layer and quickly stepping down to the deeper weak layers.

The new snow will require several days to settle and stabilize.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely - Certain

Expected Size

1 - 3

Valid until: Mar 11th, 2014 4:00PM