Archived

Avalanche Forecast

Nov 27th, 2015–Nov 28th, 2015

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

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

3: Considerable

The avalanche danger rating in the alpine will be considerable

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

3: Considerable

The avalanche danger rating in the alpine will be considerable

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

Regions: Glacier.

Sunshine and warm temps in the alpine are awfully tempting but keep in mind that the snowpack is going to undergo a rapid change in temperature. Expect avalanche danger to increase if temperatures rise above freezing, and with the strong solar.

Weather Forecast

Expect cold valley bottoms with valley cloud developing, but sunshine with a strong temperature inversion in the alpine. Above freezing temperatures are forecast above ~2000m. Light N'ly winds won't do much to help reduce the effect of warming. The high pressure system is expected to stick around until Monday or Tuesday.

Snowpack Summary

Recent strong northerly winds have reverse loaded southerly aspects creating wind slabs at ridgecrest. These slabs overlie a variety of surfaces, including suncrust on steep S-SW aspects, with 2-3mm surface hoar on most other aspects. Below this, the snowpack as a whole is strengthening. A weak basal layer exists on alpine N/NE aspects.

Avalanche Summary

Yesterday 6 size 2 avalanches were observed along the highway. They were likely triggered by the strong solar hitting the start zones. As the inversion develops over the weekend, we anticipate the recent storm snow may become increasingly reactive.

Confidence

Timing or intensity of solar radiation is uncertain

Avalanche Problems

Wind Slabs

Expect windslabs to exist where you don't normally find them. Over the past few days, reverse-loading from northerly winds have created slabs on southerly aspects.

Be cautious as you transition into wind affected terrain.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Deep Persistent Slabs

Weak, facetted snow sits at the base on shaded slopes in the alpine. This basal weakness has been responsible for several very large avalanches, and has been triggered by skiers from a shallow spot.

Avoid shallow snowpack areas where triggering is more likely.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.

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

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 3 - 4