Backcountry

Avalanche Advisory

Forecast provided by Avalanche Canada.

Daily avalanche forecasts are due to start on Friday, November 23, 2018.


BACKCOUNTRY ADVISORY

Issued at: 12/12/2018 12:56:19 AM Valid to: 12/12/2018 10:00:00 PM

This three day avalanche hazard forecast is prepared for the Sea to Sky Region including surrounding areas of Whistler Blackcomb - Terrain easily accessible as a day tour from Whistler Blackcomb’s boundaries. This advisory refers to areas outside the ski are boundary.

AVALANCHE SUMMARY

The new storm snow is bonding poorly to the old surface, small (size 1) storm slabs are being triggered by skier traffic. Explosives have triggered larger (up to size 2) storm slab avalanches.

SNOWPACK SUMMARY

Snowfall beginning Sunday has deposited around 40-60 cm in the Sea to Sky region. Strong to extreme winds have accompanied the new snow and the weather forecast is calling for significant snowfall amounts to continue to accumulate through the week.

Buried under the new snow is a weak surface layer sitting over 20-30 cm of low density faceted snow. The new snow is not bonding well with the old surface layer, has slab-like properties, and is reacting to skier traffic.

Prior to this storm, alpine snowpack depths varied around 150-200 cm, with an early November crust at bottom of the snowpack (down 100-120 cm). This crust appears to be breaking down at higher elevations and has been unreactive to snowpack tests. Snowpack depths disappear quickly with decreasing elevations (starting around 1800 m).

WEATHER FORECAST

TUESDAY NIGHT: Flurries, accumulation 10 cm, moderate west wind with strong gusts, freezing level rising 1000 m

WEDNESDAY: Snow, accumulating 15-35 cm, moderate to strong southwest wind with extreme gusts, freezing level below 1000 m

THURSDAY: Snow, accumulating 20-45 cm, moderate southwest wind with extreme gusts, freezing level rising to 1400 m

FRIDAY: Snow, accumulation 35-45 cm, strong southwest wind with extreme gusts, freezing level 1300 m

CONFIDENCE

Moderate - Intensity of incoming weather systems is uncertain

TODAY'S DANGER SCALE

Alpine
Treeline
Below treeline
4 - High
3 - Considerable
2 - Moderate

DANGER SCALE FORECAST

OVERVIEW Wednesday Thursday Friday
Alpine High High High
Treeline Considerable Considerable Considerable
Below treeline Moderate Moderate Moderate

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.
  • Naturale 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.

Storm Slabs

There have been limited alpine observations due to reduced visibility with new snowfall and high winds, expect storm slabs to be more reactive in wind-loaded terrain.

What Elevations?
What Aspect?
Chances of Avalanches?
Expected Size?

Travel and Terrain Advice

  • Minimize exposure to avalanche terrain during periods of heavy loading from new snow and wind.
  • Pay attention to overhead hazards like cornices.
  • Use caution in lee areas in the alpine and treeline. Recent storm snow has formed touchy slabs.

FORECAST DISCLAIMER

USE AT YOUR OWN RISK:

The Whistler Blackcomb 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 the 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.