Avalanche Forecast

Issued: Feb 1st, 2019 8:00AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is high. Known problems include Storm Slabs and Persistent Slabs.

andrew jones, Parks Canada

Glacier.

A widespread natural avalanche cycle is underway and storm conditions will persist until Saturday afternoon.

Summary

Weather Forecast

A low pressure system is stalling over the area for the next 2 days bringing another 35cm of new snow by Saturday afternoon. Freezing levels rise to 1300m today with an alpine high of -5 and ridge winds SW 35km/h. A transition to high pressure on Saturday evening will usher in frigid temperatures reaching a low of -26 on Sunday.

Snowpack Summary

35cm of new snow has fallen in the past 24hrs with moderate south winds. New snow sits atop hard wind slabs in the alpine. The January 17 surface hoar is buried 60cm and is most reactive between 1400-1900m, and where it overlies a crust on steep solar aspects. Several crusts exist in the upper snowpack on steep south aspects.

Avalanche Summary

A small natural avalanche cycle began yesterday with the arrival of the storm front. This morning larger avalanches (size 2-3) were observed in the highway corridor. Natural avalanche activity is expected to persist for the next 2 days as the storm snow continues to accumulate.

Confidence

Problems

Storm Slabs

35cm of storm snow has created a reactive storm slab problem. Another 35cm of snow is expected to fall by Saturday afternoon with strong winds. Rapid loading will turn these slabs into a widespread touchy problem where natural avalanches are certain.

Avoid avalanche terrain during periods of heavy loading from new snow and wind.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely - Certain

Expected Size

1.5 - 3

Persistent Slabs

The Jan 17th Surface Hoar layer is now down 60cm. This layer exists on all aspects, and is most problematic between 1400-1900m and on steep solar aspects where it overlies a crust.

Convex features and steep unsupported slopes will be most prone to triggering.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 2.5

Valid until: Feb 2nd, 2019 8:00AM