Avalanche Forecast
Purcells
As storm snow settles, persistent slab problems emerge. Sheltered treeline elevations are a primary concern.
Avalanche Problem 1: Persistent Slabs
What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?
Travel and Terrain Advice
- Watch for signs of slab formation such as whumpfing, or cracking.
- Buried surface hoar is more likely to be preserved in sheltered openings below the alpine.
Avalanche Problem 2: Wind Slabs
What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?
Shifting winds have been redistributing storm snow into wind slabs on a variety of aspects. Northwest winds were the most recent. Exercise extra caution at lower elevations where winds may have formed a slab over a touchy surface hoar layer.
Travel and Terrain Advice
- Be aware of variable wind loading patterns.
- Travel on ridges and/or ribs to avoid wind loaded slopes below
Avalanche Summary
A MIN report from the Dogtooth Range on Saturday showed a continuation of remote triggered Size 1 releases occurring in sheltered areas below treeline. Ski cutting (and explosives) also successfully produced several Size 1.5 releases over facets and surface hoar in the alpine. Another MIN report from Friday included observations of ski traffic easily producing shooting cracks between 1700-2000m in the Dogtooth.
Persistent slab avalanche danger can be expected to persist in areas where last week's storm snow consolidates into a slab above the December 15 interface. In areas where new snow has not yet consolidated into a slab, expect continued potential for triggering loose dry avalanches in steep terrain.
Snowpack Summary
Last week's stormy weather brought 30-50cm of new snow to the region. Shifting winds over recent days have redistributed this storm snow into wind slabs on a variety of aspects at higher elevations while cold temperatures have worked to inhibit slab formation in wind-sheltered areas. The storm snow lies over a wide variety of old surfaces, including large surface hoar (weak, feather-like crystals), hard crusts formed by sun or wind, and sugary facets. The bond at this old snow interface is of critical importance where the overlying storm snow has consolidated into a slab. The most concerning areas are those that saw pronounced surface hoar development before the storm, particularly in sheltered areas at and below treeline. Recent snowpack tests show wide ranging reactivity at this interface but suggest that it may be most reactive on northerly aspects.
A crust which was formed by rain in late November remains a major feature in the snowpack and is down approximately 60-100cm at tree line elevations. This interface shows good signs of bonding in the Purcells, but has indicated some reactivity in steep, variably loaded features in adjacent regions.
Weather Forecast
Monday: A mix of sun and cloud. Light variable winds. Alpine temperatures around -17.
Tuesday: Mainly cloudy. Light southwest winds. Alpine temperatures around -16.
Wednesday: Cloudy with isolated flurries bringing a trace of new snow, increasing overnight. Light southwest winds. Alpine temperatures around -15.
Avalanche Forecasts in your Inbox
Avalanche Canada has switched to an RSS feed for its daily forecasts. This is a much more flexible method that allows automatic delivery to your email inbox, or to an RSS reader of your choice.
What are RSS feeds?
RSS (Really Simple Syndication) is a popular standardized file format allowing up-to-date delivery of web-based content. RSS feeds enable you to receive content updates from websites, delivered to your email through an RSS aggregator (such as blogtrottr.com) or viewed through applications called RSS readers (such as feedly.com).
Set up an RSS feed for your email:
Select a RSS aggregator
- Purcells URL:
http://www.avalanche.ca/api/forecasts/purcells.rss - Copy the url and paste it into the appropriate field of your RSS aggregator.
- Fill in your email address.
- Voila! Watch the Avalanche Canada forecast roll into your inbox.
Forecast Disclaimer
Avalanche Canada's Public Avalanche Bulletin, and other information and services provided by Avalanche Canada, are intended for personal and recreational purposes only.
**THIS INFORMATION IS PROVIDED "AS IS" AND IN NO EVENT SHALL THE PROVIDERS BE LIABLE FOR ANY DAMAGES, INCLUDING, WITHOUT LIMITATION, DAMAGES RESULTING FROM DISCOMFORT, INJURY, OR DEATH, CLAIMS BY THIRD PARTIES OR FOR OTHER SIMILAR COSTS, OR ANY SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, ARISING OUT OF THE USE OF THE INFORMATION.**
The user acknowledges that it is impossible to accurately predict natural events such as avalanches in every instance, and uses the data in this bulletin with this always foremost in mind. The accuracy or reliability of the data is not guaranteed or warranted in any way and the Providers disclaim liability of any kind whatsoever, including, without limitation, liability for quality, performance, merchantability and fitness for a particular purpose arising out of the use, or inability to use the data.
Reactivity at the buried December 15 interface will likely be greater where the new snow has settled into a cohesive slab above buried surface hoar. Use extra caution around steeper, sheltered slopes at treeline and below.