Avalanche Forecast

Issued: Feb 19th, 2017 8:00AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

Parks Canada chris gooliaff, Parks Canada

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

Summary

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

Problems

Wind Slabs

An icon showing 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

An icon showing 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

Valid until: Feb 20th, 2017 8:00AM