Avalanche Forecast

Issued: Mar 9th, 2020 4:00PM

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

Parks Canada aaron beardmore, Parks Canada

Email

A forecasted wind event is expected on Tuesday creating fresh wind slabs.

Summary

Weather Forecast

The high pressure system will start to close out on Tuesday. As this happens wind will increase significantly from the SW in to the strong to extreme range. Snow will start Tuesday afternoon and by Wednesday morning expect up to 15cm. Temperatures will stay in the range of -5 in the valley and -15 at the ridge.

Snowpack Summary

In the alpine the wind is starting to produce soft slabs in lee areas. New sun crusts exist on steep solar aspects. 40-50 cm of recent snow sits over the Feb 29 crust interface on steep solar aspects. In thin snow pack areas a dense mid-pack sits over a weak, faceted base, while thick areas have a stronger base.

Avalanche Summary

Avalanche control on Mt Dennis produced results to size 3 (large cornices that entrain facets and new snow). Evidence of avalanches up to size 3 from the cycle from the past few days in the Little Yoho region.

Confidence

Due to the number and quality of field observations on Monday

Problems

Wind Slabs

An icon showing Wind Slabs

This problem has transitioned from a storm slab. The wind is expected to pick up significantly on Tuesday, creating new wind slabs. Expect to find storm slabs in isolated areas as the wind increases.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Recent snow has increased the load on the basal facets and we continue to see occasional results on this layer. Avalanches are most likely in areas with a thin snowpack (<130cm) where the basal facets and depth hoar are the weakest.

  • Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
  • Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3.5

Valid until: Mar 10th, 2020 4:00PM