Avalanche Forecast

Lizard Range and Flathead

Date issued

Jan 11, 2018 - 4:34 PM

Valid until

Jan 12, 2018 - 2:00 PM

Prepared by

mconlan

A Special Public Avalanche Warning is in effect for this region. Widespread avalanche activity is occurring, even on surprisingly low-angled and treed slopes. Travel in avalanche terrain is not recommend.

Regular season
Thursday - January 11, 2018
Alpine

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.

Treeline

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.

Below Treeline

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.

Friday - January 12, 2018
Alpine

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.

Treeline

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.

Below Treeline

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.

Saturday - January 13, 2018
Alpine

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.

Treeline

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.

Below Treeline

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.

Avalanche Problem 1: Storm Slabs

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

Many avalanches have been naturally and human-triggered in the recent 100+ cm of snow. If triggered, storm slabs could step down to deeper persistent weak layers.  This snowpack setup has spooked even the most experienced professionals.

Travel and Terrain Advice
  • Use caution when entering lee areas. Recent wind loading may have created wind slabs.
  • Avoid exposure to terrain traps where the consequence of any avalanche could be serious.
  • Avoid exposure to overhead avalanche terrain. Large avalanches may reach the end of run out zones.

Avalanche Problem 2: Persistent Slabs

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

Skier and machine traffic have triggered large avalanches on buried weak layers, even in fairly dense trees and shallow slope angles. These weak layers are touchy and can produce very large, destructive avalanches that run far.

Travel and Terrain Advice
  • Use caution above cliffs and terrain traps where avalanches may have severe consequences.
  • Minimize overhead exposure during periods of heavy loading from new snow and wind-transported snow.
  • Travel in avalanche terrain is not recommended with current conditions.

Avalanche Summary

A widespread avalanche cycle was observed on Tuesday through Thursday. Numerous large natural avalanches (size 3 to 3.5) were triggered in the alpine and ran to near the valley floor and numerous size 2 avalanches started at and below treeline. Operators also reported numerous large human, vehicle, and remote-triggered avalanches.  Some of these avalanches ran on relatively shallow slope angles (around 30 degrees) and in fairly dense trees.  Expect continuing avalanche activity because of the touchy snowpack.

Snowpack Summary

The snowpack reached its tipping point on Tuesday and Wednesday as warming and precipitation combined to overload buried persistent weak layers in the snowpack and create a large natural avalanche cycle.

Over 100 cm of snow has fallen in the past few days.  The snow fell relatively warm with moderate winds, which has formed storm slabs.  The snow also formed large cornices.  Deeper in the snowpack, an unstable weak layer from mid-December (predominantly feathery surface hoar crystals and/or a sun crust) is found at treeline and below treeline elevations.  Below, a rain crust that developed late-November with associated sugary facets are also being stressed. Snowpack test results show sudden fracture characters and high propagation potential for both of these buried layers, indicating that they can be triggered and could propagate into large, destructive avalanches. This has been the case, as shown in the Avalanche Summary.

Weather Forecast

FRIDAY: Mostly cloudy with intermittent snowfall, moderate westerly winds, alpine temperature near -8 C, freezing level below valley bottom.

SATURDAY: Mostly cloudy with intermittent snowfall, moderate westerly winds, alpine temperature near -5 C, freezing level near 1000 m with possible inversion conditions.

SUNDAY: Partly cloudy with valley cloud, light to moderate westerly winds, alpine temperature near 0 C, freezing level near 1300 m with inversion conditions.

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. Lizard Range and Flathead URL: http://www.avalanche.ca/api/forecasts/lizard-range.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.