Archived

Avalanche Forecast

Feb 16th, 2017–Feb 17th, 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

3: Considerable

The avalanche danger rating below treeline will be considerable

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Glacier.

Rain at low elevations, and heavy snow in the alpine is rapidly adding load to the snowpack. The upper snowpack was already moist from warm temps and is expected to be easily triggered by light loads. Be cautious until freezing levels lower.

Weather Forecast

Freezing levels are expected to stay around 1800m but should drop to 1100m overnight. A mix of rain and snow will add load to the moist snow at low elevations, and ~10cm of heavy snow in the alpine. SW winds will continue to load lees. Friday and Sat temps should have lowered to -7'C in the alpine with isolated flurries and freezing levels at 1400m

Snowpack Summary

Freezing levels rose yesterday and hovered around 2000m overnight. At 1900m ~7cm fell mixed with 3mm of rain, at 1300m we got 5 cm of snow and 3mm of rain. At TL and above ~15cm of snow sits on suncrust on solar aspects and surface hoar in areas sheltered from sun and wind. The top 20-40cm of snow is moist on all aspects to TL.

Avalanche Summary

Yesterday, moderate S'ly winds loaded lee aspects and triggered size 2 avalanches from paths with steep N facing start zones. On N aspects in the alpine, stubborn windslabs were reported to be reactive to skiers producing size 1 avalanches. At low elevations, loose wet avalanches were observed this morning up to size 2.

Confidence

Avalanche Problems

Persistent Slabs

Weak layers in the top meter include sun crust on solar slopes and pockets of surface hoar. Snowpack tests have been finding isolated sudden planar results, making them hard to predict. With the added load of rain/heavy snow they may be more reactive

Watch for signs of instability such as whumpfing, or cracking. Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Loose Wet

With up to 50cm of moist snow on the surface, loose wet avalanches are expected today and may be triggered by light loads such as skiers and even tree bombs. Although likely to be small, wet avalanches are powerful and can occur even on small slopes

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Ski short pitches and regroup in safe spots.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Moderate S-SW winds continue to load lee slopes in the alpine. They are most likely to exist on N'ly aspects in the alpine where you might be hunting for dry snow. Watch for touchy windslabs along the immediate lee of alpine wind exposed features.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Use ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2