Parks Canada aaron beardmore, Parks Canada

Little Yoho Avalanche Forecast

Jan 14th, 2020 4:00PM

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

Extreme cold has helped conditions. However, a warming trend and incoming snow starting Thursday will elevate the hazard rating.

Summary

Weather Forecast

The polar vortex persists, but there is light at the end of the tunnel. A slight warming trend is starting tomorrow and valley temperatures are expected to crest at about -5 on Thursday. The incoming warming trend will bring approx 15cm by Friday morning. Throughout this period wind will be strong from the SW and then drop to light.

Snowpack Summary

30-50 cm of snow since Dec 31 sits over a variety of surfaces including facets, surface hoar and sun crust. Windslabs may still exist in leeward alpine areas. In most areas there is a settled mid-pack over top of weaker basal layers.

Avalanche Summary

Sunshine Patrol heard to large audible avalanches in the Delerium Dive area which were cornice triggered this afternoon. No other avalanches observed or reported.

Confidence

Due to the number and quality of field observations on Tuesday

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2.5

Wind slabs still exist in the alpine and at treeline elevations from incremental snow fall and wind. Pay attention at the local level for new wind slab development.

  • Use caution in lee areas. Recent wind loading has created reactive slabs.

Aspects:

North, North East, East, South East, South, North West.

Elevations:

Alpine, Treeline.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

1 - 2.5

This layer may present as surface hoar / facets / or sun crust. It is buried 30-60 cm throughout the region and is producing 'sudden planar' results in stability tests.

  • If triggered the persistent slab may step down to deeper layers resulting in large avalanches.

Aspects:

All aspects.

Elevations:

Treeline, Below Treeline.

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3.5

The potential for deeper releases on the basal layers still exist. Several large avalanches have occurred on this layer in past few days. See forecast details.

  • Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
  • Avoid shallow snowpack areas where triggering is more likely.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Jan 15th, 2020 4:00PM