Archived

Avalanche Forecast

Feb 19th, 2017–Feb 20th, 2017

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

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: Glacier.

Brief sunny breaks can rapidly increase danger levels on southerly aspects. The mid-February sun has some punch to it.

Weather Forecast

Mainly cloudy today with isolated flurries, light to moderate SW winds, and alpine highs of -5*C. The sun may pop out for brief periods so expect warmth with its appearance. Freezing levels rising to 1500m by the afternoon. Flurries tonight bringing up to 5cm of snow, then a slightly cooler Monday with isolated flurries.

Snowpack Summary

20-40 cm of storm snow sits on top of a strong temperature or sun crust. At higher elevations where sheltered from sun and wind, the storm snow buried surface hoar. Mod to strong south winds have formed windslabs at ridgetop. At lower elevations, the rain-soaked upper snowpack has frozen into a crust on the surface.

Avalanche Summary

No new avalanches observed yesterday. Whumphing and cracking was observed in the alpine along shallow, faceted S/SW aspects at ridge-top. The cooler temp's have ended the natural avalanche cycle from several days ago, where avalanches were generally in the size 2-2.5 range, with lots of activity at lower elevations.

Confidence

Timing or intensity of solar radiation is uncertain

Avalanche Problems

Wind Slabs

Strong southerly winds from 2 days ago created wind slabs on northerly aspects and exposed areas above tree line. These are settling and bonding to the upper snowpack, but need careful consideration as you first enter the slope at the top.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Be aware of the potential for wide propagations due to the presence of hard windslabs.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

Weak layers in the top meter include sun crust on solar slopes and pockets of surface hoar. Tests show isolated sudden planar results, making them hard to predict. Be cautious in shallow snowpack areas (ridge-crests) where triggering is more likely.

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

Expected Size: 2 - 3