Avalanche Forecast

Issued: Jan 24th, 2018 4:46PM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Cornices.

jsmith, Avalanche Canada

Sea To Sky.

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 Thursday.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

WEDNESDAY NIGHT: 10-20cm of new snow / Moderate to strong southerly ridgetop winds / Freezing level around 500m.THURSDAY: 10-20cm of new snow / Moderate to strong southerly ridgetop winds / Freezing level dropping to 700m.FRIDAY: 5-10cm of new snow / Light to moderate southerly ridgetop winds / Freezing level around 500m.SATURDAY: 5-10 cm of new snow / Moderate southwesterly ridgetop winds / Freezing level around 500m.

Avalanche Summary

On Tuesday, a natural size 2.5 storm slab avalanche was reported near Whistler. It was reported as being about a day old and no further information was reported.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. 20 cm of new snow on Wednesday morning continues to be redistributed by strong southeasterly winds. Last weekend's storm likely created dense storm slabs lurking in lee and cross-loaded features. Impressive cornice growth is also expected to have occurred.About 180cm 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.

Problems

Storm Slabs

Forecast new snow and wind on Wednesday night are expected to continue to create touchy storm slabs reactive to human triggers.

Be cautious as you transition into wind affected terrain.Be aware of the potential for wide propagations due to the presence of hard windslabs.The new snow will take time to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Cornices

Large amounts of recent new snow and high winds are creating rapid cornice growth.

Falling cornices may trigger large avalanches on the slopes below.Give cornices a wide berth when travelling on or below ridges.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Valid until: Jan 25th, 2018 2:00PM