Parks Canada Conrad Janzen, Parks Canada

Banff Yoho & Kootenay National Park Avalanche Forecast

Mar 22nd, 2020 5:01PM

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

New snow, wind and warmer temperatures will elevate the avalanche danger on Monday. Narrow gullies and steep rocky terrain may have small natural avalanches. Step back to more moderate terrain choices until the new snow has a chance to bond.

Summary

Weather Forecast

Snow is expected Sunday night and Monday with total amounts ranging from 10-15 cm depending on the elevation. Winds will increase into the moderate to strong range out of the SW on Monday before dropping down to light again on Tuesday. Freezing levels stay just above valley bottom and some areas could see rain at lower elevations on Monday. 

Snowpack Summary

2-5 cm of new snow in eastern areas of the forecast region on Saturday night. Widespread wind effect in the alpine and down into treeline. Sun crusts on solar aspects and buried sun crusts on steep solar aspects. In thin snow pack areas a dense mid-pack sits over a weak faceted base, while deep snowpack areas have a solid base.

Avalanche Summary

Several solar triggered small loose avalanches observed in the past several days and some skier triggered surface sluffing in steep terrain up to size 1.5.

Confidence

Intensity of incoming weather systems is uncertain on Monday

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Incoming snow and moderate to strong SW winds Monday will create fresh wind slabs in lee areas at treeline and above. These will be possible to trigger by skiers. Avoid wind loaded areas in steep terrain, especially in thin snowpack areas.

  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Likelihood

Possible - Unlikely

Expected Size

2 - 3

Use caution in thin snowpack areas averaging 150cm or less. In these areas the basal snowpack layer of depth hoar and facets remains weak, and the mid and upper snowpack is thin enough to allow for triggering of the deep persistent layer.

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

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Mar 23rd, 2020 4:00PM