Avalanche Forecast

Cariboos

Date issued

Feb 11, 2018 - 4:16 PM

Valid until

Feb 12, 2018 - 2:00 PM

Prepared by

pgoddard

A Special Public Avalanche Warning is in effect. Copy this link to view details: http://bit.ly/2nSOUyX

Regular season
Sunday - February 11, 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

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.

Monday - February 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

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.

Tuesday - February 13, 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.

Avalanche Problem 1: Persistent Slabs

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

Several troublesome layers exist in the snowpack. Although the likelihood of triggering a persistent slab has gone down, the consequences remain very high.

Travel and Terrain Advice
  • Avoid lingering in runout zones. Avalanches have the potential to run to valley floor.
  • Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.
  • Avoid steep convexities or areas with a thin or variable snowpack.

Avalanche Problem 2: Wind Slabs

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

Recent north-westerly winds have left behind wind slabs and cornices on lee slopes.

Travel and Terrain Advice
  • Travel on ridgetops to avoid wind slabs on slopes below.
  • If triggered, wind slabs may step down to deeper layers resulting in large avalanches.
  • Give cornices a wide berth when travelling on or below ridges.

Avalanche Summary

A very large, widespread avalanche cycle was observed on Thursday and Friday. Slopes of all aspects and elevations ran full path and reached valley floor. In some cases, mature timber was destroyed. Many of these failed on persistent weak layers, while some involved only the recent storm snow.

The natural cycle has wound down, but human-triggering remains a real concern. Avalanches are most likely to be triggered with a large load, (like a snowmobile landing a jump, a cornice fall, or a solar-triggered avalanche stepping down), or from a thin-spot trigger point, like around trees or rocks. You might be surprised by how large an avalanche can be triggered and how far it could run.

Snowpack Summary

Strong north to north-westerly winds have loaded lee slopes with 30-40 cm recent storm snow. This adds to an existing storm slab up to 1m deep from the last couple of weeks' accumulation.

Several persistent weak layers make up a troublesome snowpack. In the top 1-1.5 m of the snowpack, two surface hoar layers buried in January can be found. Expect to find one or other of these on all aspects and elevations.

Deeper in the snowpack (120-200 cm deep) is a facet/crust/surface hoar layer from December, most prevalent at and below treeline.

Near the base of the snowpack is a crust/facet combo, most likely to be triggered from thin spots in the alpine.

All of these layers have produced large avalanches recently. The wide distribution and ongoing reactivity of these layers suggests that avoidance through choosing simple terrain is the best strategy.

Weather Forecast

MONDAY: Mainly sunny, with increasing clouds late in the day. Light winds. Treeline temperature near -10.

TUESDAY: 20-30 cm snow. Moderate westerly winds. Treeline temperature near -5.

WEDNESDAY: Flurries. Light winds. Treeline temperature near -8.

More details can be found in the Mountain Weather Forecast.

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?

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Set up an RSS feed for your email:

Select a RSS aggregator

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