Avalanche Forecast

Northwest Coastal

Date issued

Jan 30, 2018 - 4:07 PM

Valid until

Jan 31, 2018 - 2:00 PM

Prepared by

shorton

Large destructive avalanches are very likely as new snow accumulates. Stick to simple low-angled terrain.

Regular season
Tuesday - January 30, 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

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.

Below Treeline

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.

Wednesday - January 31, 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

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.

Below Treeline

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.

Thursday - February 1, 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

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.

Below Treeline

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.

Avalanche Problem 1: Storm Slabs

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

Over 50 cm of new snow has formed very touchy storm slabs, especially in wind-affected terrain at higher elevations.

Travel and Terrain Advice
  • Minimize exposure during periods of heavy loading from new snow and wind.
  • Use conservative route selection, choose moderate angled and supported terrain with low consequence.
  • Be cautious as you transition into wind affected terrain.

Avalanche Problem 2: Persistent Slabs

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

Buried weak layers in the snowpack have produced some recent large avalanches in steep, unsupported terrain. These layers may be sensitive under the weight of all the new snow.

Travel and Terrain Advice
  • Avoid shallow, or thick to thin snowpack areas where triggering a deeper layer is more likely.
  • Watch for signs of instability such as whumpfing, or cracking.

Avalanche Summary

Natural avalanche activity was likely widespread during Tuesday's storm.

Reports from Monday include a cycle of natural storm slab avalanches (up to size 2), several small (size 1) human-triggered slab avalanches, and dry loose avalanches (up to size 1.5). On Saturday, a size 2 remotely (from a distance) triggered persistent slab avalanche was reported to have run on a northeast aspect in the alpine on buried layer of surface hoar.

Snowpack Summary

Heavy snowfall in the Terrace area has delivered over 50 cm of new snow at the time of publishing (4 pm Tuesday), with another 10-20 cm possible by Wednesday afternoon. With this much new snow, storm slabs will be very touchy.

60-100 cm of snow now covers a widespread layer that was buried in mid-January. This layer is primarily a crust, while surface hoar may be found in sheltered areas at treeline and below. Last week this weak layer produced sudden results in the Shames area and avalanche activity at upper treeline and alpine elevations. Professionals have also been monitoring a few deeper layers including a 100-140 cm deep crust / surface hoar layer that was buried in early-January, and a similar layer buried in mid-December that now lies 120-150 cm below the surface. Both of these layers have been reactive in recent snowpack tests and produced large natural avalanches in northern parts of the region near Bear Pass.

The lower snowpack is generally strong, with the exception of areas around Stewart and further north where a basal crust and facets exist.

Weather Forecast

WEDNESDAY: Snow with accumulations of 5-10 cm Tuesday night and 5-10 cm on Wednesday / moderate southwest wind / alpine temperatures around -5 C.

THURSDAY: Flurries, accumulations of 5-10 cm / moderate southwest wind / alpine temperatures around -7 C.

FRIDAY: Snow with accumulations of 15-30 cm / moderate to strong southwest wind / alpine temperatures around -7 C.

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. Northwest Coastal URL: http://www.avalanche.ca/api/forecasts/northwest-coastal.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.