Archived

Avalanche Forecast

Dec 19th, 2017–Dec 20th, 2017

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Sea To Sky.

In the wake of Tuesday's storm, be vigilant for wind loading - even at lower elevations. Extra caution on south through east aspects!

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

After Tuesday's storm it will clear up and we'll have dry weather with cool temperatures for the foreseeable future.WEDNESDAY: Sunny with occasional cloudy periods. Ridge wind moderate northerly. Freezing level at the surface, alpine high temperatures of -4.THURSDAY: Some clouds and isolated flurries. Ridge wind moderate from the north west. Temperature near -3. Freezing level 400 m. FRIDAY: Sunny. Ridge wind moderate from the north east. Temperature near -10. Freezing level at the surface.

Avalanche Summary

On Tuesday, reactive soft slabs were reported on southerly terrain features at treeline. See here for details in the Mountain Conditions Report. Small steep features below tree line were also running naturally to Size 1 on a layer just above the Dec 15th melt-freeze crust. Ski cutting produced several storm slabs up to Size 2 at higher elevations. Also on Monday, we had reports of reactive wind slabs on steep north-facing slopes. See here for the MIN report.

Snowpack Summary

Up to 20 cm of low-density snow fell on Tuesday, accompanied by moderate to strong north west winds. Soft slabs 20-40cm thick were reactive to human traffic.There is now 30-50cm of snow sitting on a melt-freeze crust that formed on all aspects and elevations in early December. On high north aspects this crust is thin with dry, sugary snow crystals (facets) below. The lower snowpack is well settled and consists of several crusts that formed in the early season.

Avalanche Problems

Storm Slabs

Winds during Tuesday's storm were from the north west - which is not the usual pattern we see. Watch out for storm slabs on south through east aspects.

Avoid steep convex slopes.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 3