Avalanche Forecast

Purcells

Date issued

Jan 1, 2018 - 4:56 PM

Valid until

Jan 2, 2018 - 2:00 PM

Prepared by

jfloyer

Rapid warming in the alpine and a persistent weak layer 30-50 cm below the surface are both good reasons to be cautious.

Regular season
Monday - January 1, 2018
Alpine

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation,cautious route-finding and conservative decision-making essential.

Natural avalanches possible;human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Below Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Tuesday - January 2, 2018
Alpine

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation,cautious route-finding and conservative decision-making essential.

Natural avalanches possible;human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Below Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Wednesday - January 3, 2018
Alpine

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Below Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Avalanche Problem 1: Persistent Slabs

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

A weak layer of surface hoar buried 30-50 cm deep is expected to become more reactive as warmer temperatures help settle recent new snow into a cohesive slab.

Travel and Terrain Advice
  • Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Approach steep open or sparsely treed slopes cautiously.

Avalanche Problem 2: Wind Slabs

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

Wind slabs have been reported and are likely to continue to develop in exposed terrain. Warmer temperatures at higher elevations may also make the upper snowpack denser.

Travel and Terrain Advice
  • Use ridges or ribs to avoid pockets of wind loaded snow.
  • Be cautious as you transition into wind affected terrain.
  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Avalanche Summary

On Sunday, a size 1.5 avalanche involving two people near Invermere was reported. It was suspected to have run on the mid-December weak layer. On Saturday a skier triggered size 2 persistent slab avalanche running on a layer of facetted snow from mid-December was reported. This happened in the north of the region's Dogtooth Range on a west aspect at 2400m. Expect the potential to trigger persistent slabs to increase as last week's storm snow continues to settle into a cohesive slab.

Snowpack Summary

20-40 cm low density new snow has accumulated and buried a recently formed layer of weak feathery surface hoar and/or sugary facets. Another layer buried mid-December that consists of surface hoar, sun crust and/or sugary facets is down approximately 40-70cm and has been reported at elevations up to 2400 m. 

A rain crust that formed in late November is now buried 70-110cm deep. Recent reports show this layer to be unreactive at this time.

Weather Forecast

Tuesday: Cold air in the valleys, warmer air up high. An above freezing layer is expected from approximately 2300-2700 m. Some valley cloud is possible, clear at upper elevations. Light southwesterly winds.

Wednesday: basically a repeat of Tuesday, possibly slightly warmer.

Thursday: Cloud developing later in the day. Lower elevations getting warmer, although the above freezing layer is expected to remain in place. Light southwesterly winds.

Danger Ratings Explained

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

Natural avalanches possible; human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

4 - High

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Natural avalanches likely; human-triggered avalanches very likely.

Large avalanches in many areas; or very large avalanches in specific areas.

5 - Extreme

Avoid all avalanche terrain.

Natural and human-triggered avalanches certain.

Large to very large avalanches in many areas.

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

  1. Purcells URL: http://www.avalanche.ca/api/forecasts/purcells.rss
  2. Copy the url and paste it into the appropriate field of your RSS aggregator.
  3. Fill in your email address.
  4. 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.