Avalanche forecast

Sea To Sky

Jan 24, 2018Avalanche Canada
View on map
Archived · expired 9 years ago

Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
3 · Considerable
Below
2 · Moderate
Open full map

Highlights

New snow and wind are creating deeper and increasingly destructive storm slabs ripe for human triggering. Sticking to simple terrain would be a great way to manage the elevated hazard on Wednesday.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2.5
    An impressive storm has just occurred, and deep and dense storm slabs lurk in lee and cross-loaded terrain. New snow and wind on Tuesday will add to this ongoing storm slab problem. Watch for very touchy storm slabs on Wednesday.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Tuesday Night: 10-30cm of new snow(more in the south) / Strong to extreme southerly ridgetop winds / Freezing level around 1200m.Wednesday: 5-20 cm of new snow / Moderate southwesterly ridgetop winds / Freezing level around 1100m.Thursday: 5-10 cm of new snow / Moderate southwesterly ridgetop winds / Freezing level around 800m.Friday: Mostly cloudy with flurries; 3-5cm / Light southwesterly ridgetop winds / Freezing level around 800m.

Avalanche Summary

An impressive natural storm slab avalanche cycle occurred in response to new snow and wind on Monday. In some of the big east-facing terrain to the west of the Upper Lillooet Valley, evidence of natural activity to size 4 was observed, while explosives control produced storm slabs in the size 1.5-3.5 range.Looking forward, forecast snow and wind will promote ongoing surface storm slab avalanche activity, while surprisingly deep releases within (or at the base of all of the recent storm) snow may be possible in isolated terrain.

Snowpack Summary

The region has been pummeled by heavy snowfall and extreme southerly winds. By Tuesday morning the 72 hour snowfall totals were just over 100cm. Thanks to extreme southeast winds, I would anticipate extensive scouring and redistribution of the recent storm snow at all elevation bands with dense storm slabs lurking in lee and cross-loaded features. Impressive cornice growth is also expected to have occurred.About 150cm below the surface you'll find a crust that was buried mid-January and is present at all elevations. This crust is thin on northerly aspects and up to 3 cm thick on solar aspects. Most reports suggest an improving bond at this interface, but the load of the new snow may tip the balance and reactivate this layer in isolated terrain. Below this, the snowpack is generally strong and well-settled.

Regions covered