Avalanche Forecast

Issued: Mar 21st, 2015 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs, Loose Wet and Deep Persistent Slabs.

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

Watch locally for sun effect on the new snow in the alpine as this will increase the avalanche danger. We probably will not see a decent freeze in large portions of the region to start Sunday. SH

Summary

Weather Forecast

A small pulse of snow which could produce another 5-10cm and rain below 1800m is moving through the forecast region Saturday night.Â Freezing levels to 1700m Sunday with a mix of sun and cloud and light to moderate westerly winds.Â

Snowpack Summary

10 - 15cm of snow over the last 48 hours in the alpine with moderate SW winds and temps near 0`C. Wind slabs present in isolated lee and open areas in the alpine. The recent snow sits on a variety of stiffer surfaces. The base of the snowpack is made up of facets and depth hoar and remains weak. Below tree line snow is isothermal in the afternoons

Avalanche Summary

Local ski areas were able to ski cut small wind slabs (sz.1) in immediate lee areas on Saturday.Â

Confidence

Freezing levels are uncertain on Sunday

Problems

Wind Slabs

10 cm of recent storm snow has formed wind slabs up to 35cm in the lee areas at treeline and above. These will be sensitive to human triggering on features such as ridge crests and cross loaded gullies. Cornices are also becoming a concern.

Be cautious as you transition into wind affected terrain.Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

Rain below 2000m Saturday means the snowpack will likely be isothermal below treeline and some treeline areas.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The lower half of the snowpack is weak due to the presence of basal facets and depth hoar. This layer has been dormant lately but may become more sensitive with the forecasted new snow load, especially in thin areas.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 22nd, 2015 4:00PM