Avalanche Forecast

Issued: Mar 27th, 2015 4:00PM

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

patrick jerome, Parks Canada

Banff Yoho Kootenay.

The freezing levels should lower tonight and form crusts. Pay attention to the strength of these crusts at tree line and below this weekend as the wet snow beneath has no strength. Cornices are weak and fragile on north aspects so keep an eye out.

Summary

Weather Forecast

The winds will abate as a cold front passes tonight ushering in cooler air and lower freezing levels along with some light precipitation amounts for Saturday morning. Strong westerly winds at ridgetop will continue mid Saturday through the weekend with scattered precipitation.

Snowpack Summary

Sustained moderate to strong winds aloft continued to build wind slabs and cornices at ridge top today. Moist snow to 2400 meters on polar aspects (North) and moist to ridge top on the solar slopes. Mid pack is well settled and overlies a largely weak basal depth hoar or facets.

Avalanche Summary

Several natural avalanches occurred today up to size 2.5 around the Sunshine Ski Area back country. Many loose wet avalanches with some of them triggering slab avalanches in the lower track below tree line. Suspect with today's warm temps that cornices will be very touchy.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Saturday

Problems

Wind Slabs

There is generally 10-20 cm available for transport and moderate to strong SW wind continues to build windslabs. They are sensitive to human triggering on features such as ridge crests, cross loaded gullies, and steep lee terrain features.

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

Rising freezing levels on Friday has the potential to create a loose wet avalanche problem on solar aspects

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

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 rising temperatures.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 3

Valid until: Mar 28th, 2015 4:00PM