Avalanche Forecast

Issued: Mar 12th, 2019 4:00PM

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

grant statham, Parks Canada

Little Yoho.

ICE CLIMBERS AND SKIERS - avalanche control will occur on Wednesday on Mt. Bosworth, Stephen, Field and Dennis. No skiing or climbing in any of these areas please. All of the Field beer climbs are closed for Wednesday.

Summary

Weather Forecast

A system crossing the area overnight on Tuesday will deposit another 5-10 cm before it ends mid-day on Wednesday. Temperatures will remain in the -10 range and winds look to be generally light.

Snowpack Summary

Strong SW winds overnight Monday have redistributed recent snow into wind slabs in open areas above treeline. This recent snow sits over weak facets, previous wind effect or sun crusts on steep solar aspects. The mid pack varies from supportive in thicker snowpack areas to weak and completely faceted in thin areas.

Avalanche Summary

On Monday a random large avalanche ran over the ice climb Massey's and caught a group of ice climbers. We have seen no other avalanches of this nature in the park, but this is a reminder of the ever-so-fragile nature of this snowpack. Change can be almost immediate, and even small slabs will run far by gouging out weak snow in the avalanche paths.

Confidence

Due to the number of field observations

Problems

Wind Slabs

New snow and strong SW winds have built slabs in open areas above treeline. These slabs are sitting on the weak, faceted snow that was previously on the surface and as a result can run further than expected when triggered.

Watch for surface cracking and stiffer surface layers of snow.Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Loose Dry

Previous cold temperatures created weak, faceted surface snow. In steep terrain, these facets remain easily triggered and can gain enough mass to affect skiers and climbers. Narrow gullies are where this is most concerning.

Be very cautious with gully features.Use caution above cliffs and terrain traps where small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 13th, 2019 4:00PM