Avalanche Forecast

Issued: Mar 3rd, 2017 4:00PM

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

tim haggarty, Parks Canada

Banff Yoho Kootenay.

An avalanche cycle is expected over the next 24 hours as a reasonably intense storm passes through the area. Large avalanches on the persistent layers would not be surprising with cornices, windslabs and even loose dry avalanches as possible triggers

Summary

Weather Forecast

A low is passing over the Jasper area early Friday afternoon with a cold front to follow into the forecast region. Heavy snowfall combined with strong SW winds in the alpine are expected to create rapid loading. Temperatures have reached their peak Friday afternoon and can be expected to cool to -10C values at Treeline for Saturday morning.

Snowpack Summary

Wind slabs are developing at tree line and above with incoming snow and strong SW winds. Below 1850m a thin rain-crust sits below 10-15cm of recent snow. Common throughout the region are the weak facets and depth hoar in the lower half of the snowpack with a 40 to 60 cm stiff slab sitting above them.

Avalanche Summary

No new avalanche activity was observed or reported on Thursday.

Confidence

Intensity of incoming weather systems is uncertain on Friday

Problems

Wind Slabs

New snow and strong SW winds are forming fresh windslabs and sensitive cornices. If these fail they could provide enough of a load to trigger deep persistent layers resulting in large avalanches.

Use caution in lee areas. Recent wind loading has created wind slabs.Pay attention to overhead hazards like cornices which could easily trigger deep slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

There is a thick slab over a structurally weak snowpack in most areas. Avoid thin parts of a slope or rocky outcrops at tree line and above. We may see increased natural activity through the storm on Friday and Saturday.

Be aware of thin areas that may propogate to deeper instabilites.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Loose Dry

Watch for the new snow to fail easily in steep terrain. Use caution in confined features and around terrain traps such as cliffs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2

Valid until: Mar 4th, 2017 4:00PM