Skip to main content
Whistler Blackcomb, Whistler, BC Canada
Whistler Blackcomb, Whistler, BC Canada
Backcountry

Avalanche Advisory

Forecast provided by Avalanche Canada.

BACKCOUNTRY ADVISORY

Issued at: 4/19/2018 5:30:50 PM Valid to: 4/20/2018 9:00:00 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

Wednesday a skier accidentally triggered a storm slab avalanche (size 1.5) on a steep, east aspect at 2600 m that released on a crust 30 cm deep. Explosive control work in the ranges west of the Pemberton Icefield produced size 3 persistent slab avalanches that are suspected to have failed on the late March weak layer. Observations of older, natural size 3-3.5 avalanches in the area where also attributed to this persistent weak layer. And older natural size 3-3.5 avalanches were also observed at 1800-2100 m in the McBride range.

On Monday, small slabs and loose wet avalanches were triggered by skiers and the sun. Slabs were reactive in lee terrain features near ridges.

On Sunday, a large (size 3) persistent slab avalanche was remotely triggered by a snowmobile on a north aspect in alpine terrain with substantial air temperature and solar warming over the day. The avalanche likely released on the late March weak layer. Also on Sunday a large avalanche was observed close to Whistler, on a north aspect around 2000 m, with a depth of about 1 m. It was suspected to have released with sun following last weekends storm, and likely on the same weak layer.

SNOWPACK SUMMARY

About 10-30 cm of recent snow has been redistributed by strong northwesterly winds. This overlies variable surfaces, including old wind slabs at high elevations, and crusts on most aspects.

A weak layer consisting of surface hoar, facets, and/or a melt-freeze crust from late March is now buried about 60 to 140 cm. This layer is spotty in its distribution and has recently produced large and destructive avalanches. It is most likely to be problematic on west, north, and east aspects between 1900 m and 2250 m. Professionals are treating this layer very cautiously and avoiding terrain because of it. Read Conditions report here.

The mid and lower snowpack are well-settled and strong.

WEATHER FORECAST

TONIGHT: Mostly cloudy, light flurries. Accumulation trace. Ridge wind light, southwest. Alpine temperature near -5. Freezing level 1100 m.

FRIDAY: Cloudy, flurries. Accumulation 2-5 cm. Ridge wind light to moderate, south. Alpine temperature near -5. Freezing level 1500 m.

SATURADY: Mostly cloudy, flurries ending. Accumulation 10-15 cm (up to 20 cm near Squamish). Ridge wind moderate, west. Alpine temperature near -5. Freezing level 1500 m.

SUNDAY: Sunny. Ridge wind light, north. Alpine temperature near -2. Freezing level 1800 m.

CONFIDENCE

Moderate -

TODAY'S DANGER SCALE

Alpine
Treeline
Below treeline
2 - Moderate
2 - Moderate
1 - Low

DANGER SCALE FORECAST

OVERVIEW Friday Saturday Sunday
Alpine Moderate Moderate Considerable
Treeline Moderate Moderate Considerable
Below treeline Low Low 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.

Persistent Slabs

Professionals are traveling cautiously due to a weak layer buried 60 to 140 cm. The layer is found in upper treeline and alpine terrain on shady aspects. Warming and cornice failures have been triggers for recent avalanches on this layer.

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

Travel and Terrain Advice

  • Avoid steep terrain or areas with a thin or variable snowpack.
  • Be aware of the potential for wide propagation due to the presence of buried weak layers.
  • Pay attention to overhead hazards like cornices, which could trigger persistent slabs.

Wind Slabs

Lingering wind slabs may still exist in alpine northerly terrain near ridge crests.

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

Travel and Terrain Advice

  • Caution in lee and cross-loaded terrain near ridge crests.

Loose Wet

The sun packs quite a punch at this time of year. Be cautious if the sun comes out or if you feel warm air temperatures. This can weaken the snow surface and increase the likelihood of loose wet avalanches especially on steep sunny aspects.

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

Travel and Terrain Advice

  • Use extra caution on slopes if the snow is moist or wet.
  • Use caution above cliffs and terrain traps where small avalanches may have severe consequences.

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.