Avalanche Forecast Banff Yoho & Kootenay National Park

Wednesday 23rd January 2019

Avalanche Danger Ratings Wed 23rd Jan 4:00PM Danger Ratings Alpine: Moderate Danger Ratings Treeline: Moderate Danger Ratings Below Treeline: Low Deep Persistent Slabs Deep Persistent Slabs Wind Slabs Wind Slabs

Parks Canada Forecaster: stephen holeczi

Date Issued:

Valid Until:

Thin areas will be the most susceptible to triggering the weaker basal facets/ depth hoar.  This problem is now hard to predict, and comes down to your level of comfort with the uncertainty combined with the type of terrain you choose.

Weather Forecast

Continued mild temperatures for January with highs in the -2 to -4C range at valley bottom and -8 to -10C at 3000m with West winds increasing to strong in the alpine.  Only a few cm of snow is expected over the next 2 days. 

Snowpack Summary

10-20cm of snow over the last few days. Thin wind slabs can be found in alpine lee areas from strong SW winds on Saturday. 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 reported or observed.

Confidence

Due to the number and quality of field observations

Deep Persistent Slabs Deep Persistent Slabs

Likelihood

Possible

Expected Size

1.5 - 3

The weak Oct.26 facets and depth hoar at the base of the snowpack have a significant slab (50-130cm thick) sitting above them. The likelihood of triggering this layer has decreased, but if it does get triggered, the avalanche will be large in size.

Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Avoid thin, rocky or unsupported slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

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Wind Slabs Wind Slabs

Likelihood

Possible - Unlikely

Expected Size

1 - 1.5

Thin wind slabs are stubborn but still show potential for triggering in the alpine.  Increased winds on Thursday may add to their development.  These will not be a long term problem. 

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: North, North East, East.

Elevations: Alpine.

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