Avalanche Forecast

Issued: Mar 10th, 2019 4:43PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

Triggering small surface slabs in steep terrain remains a concern, especially in wind loaded areas. This problem will likely increase with the arrival of new snow and strong alpine winds Monday night. Look for sheltered areas to enjoy the new snow.

Summary

Weather Forecast

Upper elevation winds will increase to strong out of the SW-W on Monday afternoon with snow arriving overnight and into Tuesday. Accumulations are forecast to be between 5-10 cm. Alpine temperatures will rise to around -8'C and remain relatively steady while valley bottoms will see temperatures above freezing.

Snowpack Summary

Up to 15 cm of recent snow with moderate to strong SW-W winds has formed thin slabs in open areas above treeline. This snow sits over either 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

Several small slabs were triggered by groups on a variety of aspects, in open areas above treeline in the last 24 hrs. Most were thin slabs but a couple stepped down to deeper facet layers. Avalanche control Sunday produced thin slabs from size 1-2.5 out of steep alpine start zones with some gathering mass as they scrubbed down into the facets.

Confidence

Forecast snowfall amounts are uncertain on Tuesday

Problems

Wind Slabs

Thin slabs can be found in wind loaded areas above treeline. These slabs are sitting on the weak, faceted snow that was previously on the surface and can be triggered by skiers or climbers.

Watch for surface cracking and stiffer surface layers of snow.The new snow will require several days to settle and stabilize.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

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.

Use caution above cliffs and terrain traps where small avalanches may have severe consequences.Good group management is essential to manage current conditions safely.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 1.5

Valid until: Mar 11th, 2019 4:00PM