Avalanche Forecast

Issued: Jan 26th, 2019 4:00PM

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

tim haggarty, Parks Canada

Little Yoho.

Strong winds are expected Sunday morning. Give overhead avalanche terrain a wide berth until winds settle back down later in day.

Summary

Weather Forecast

Freezing levels Saturday reached 2300m (new crusts) with moderate West winds. Overnight, alpine winds are forecast to increase to strong to extreme as a cold front passes bringing some precip and a cooling trend begins. Midday Sunday should bring and end to the winds as temperatures drop further. Clearing overnight into Monday.

Snowpack Summary

10-20cm of snow over the last week over isolated suncrusts and surface hoar. Widespread wind effect in the alpine creeping into treeline with current winds. Of greatest concern are the weak facets and depth hoar at the base of the snowpack. In thinner snowpack areas with less than 150 cm of snow, triggering a slab on these facets is more likely.

Avalanche Summary

No new avalanches observed or reported today.

Confidence

Wind speed and direction is uncertain on Sunday

Problems

Wind Slabs

These slabs are now a bit old and even a bit buried. Nevertheless, with strong to extreme winds in the forecast for Sunday morning, the potential for these, or cornices to fail will be elevated.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Minimize overhead exposure during periods of heavy loading from new snow, wind.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

Deep Persistent Slabs

In Little Yoho, areas with a thin snowpack with more developed faceting still raise concern. Many of the areas in this region hold a deeper snowpack where this problem is not a concern. Travelers are advised to investigate snow depths with a probe.

Be aware of the potential for wide propagations which could result in large avalanches.Avoid thin, rocky or unsupported slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 27th, 2019 4:00PM