Avalanche Forecast

Issued: Feb 13th, 2013 8:14AM

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

Parks Canada Sylvia Forest, Parks Canada

Cornices likely got overloaded last night with high to extreme winds.  A combination of buried surface hoar and wind slab will make route selection tricky today.  Look up, look around, and avoid terrain traps.

Summary

Weather Forecast

An unstable air mass will remain over the region for the day, bringing moderate westerly winds and flurries and rising freezing levels to 1100m.  An approaching warm front with an upper ridge will build over the area on Thursday and Friday, with moderate to high winds and mild temperatures for the weekend.

Snowpack Summary

A new layer of surface hoar was buried yesterday by 20 cm of new snow.  On sunny aspects, this surface hoar layer rests on top of a crust.  It is most notable between 1700-1900 m.  Below this, the mid-pack is strong, with hard failures in stability tests down 40cm.  Surface sluffing and wind slabs can be expected in steep and wind affected areas.

Avalanche Summary

25cm of new snow and high to extreme S. winds have resulted in an avalanche cycle in the park overnight.  Most of these were from steep terrain in the highway corridor, and it is likely that similar avalanche activity occurred in the backcountry as well.  Avalanches were running to the middle of the fans, and on average were size 2.5 to 3.

Confidence

Due to the number of field observations on Wednesday

Problems

Wind Slabs

An icon showing Wind Slabs
High to extreme S. winds have redistributed new snow onto lee slopes, creating hard and soft slabs in all wind affected areas.  At treeline, these slabs rest on a newly formed surface hoar layer (February 12). 
Use caution in lee areas in the alpine. Recent wind loading have created wind slabs.Watch for areas of hard wind slab in steep alpine features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Loose Dry

An icon showing Loose Dry
The volume of sluffing could knock you over; choose your climb carefully and belay when exposed.Plan escape routes and identify safe zones before committing to your line.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Feb 14th, 2013 8:00AM