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Archived

Avalanche Forecast

Jan 27th, 2018–Jan 28th, 2018
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Little Yoho.

Human triggering and some natural avalanche activity continues to occur on the various weak layers buried in our snowpack. We expect this to increase Sunday night and Monday. Minimize exposure and avoid large avalanche terrain until things improve!

Weather Forecast

Temps on Sunday will be in the -5 to-10'C range at treeline with some warming late in the day and 10-15 cm of snow, mostly later in the day. Sunday night should see a rise in temperatures and increased snowfall into Monday which will likely cause a natural avalanche cycle if the current forecast comes true.

Snowpack Summary

Recent alpine winds have created wind slabs in leeward areas up to 1m thick. 35-65 cm of settled snow from recent storms has formed a soft slab over the three persistent weak layers of surface hoar and facets that lurk in the upper half of the snowpack often giving sudden test results. Jan 16 down 35-65cm; Jan 6 down 40-75cm; Dec15 down 55-100cm

Avalanche Summary

More evidence of a widespread cycle on persistent weak layers up to size 3 in the last 48hrs was observed with debris crossing the Takkakaw Falls road below Wapta Peak and numerous slabs out at treeline in the Yoho Valley. One natural size 2.5 cornice triggered slab was observed on Mt Crowfoot near the Wapta Icefields this morning.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Monday

Avalanche Problems

Persistent Slabs

There are three weak layers in the upper snowpack: Jan 16, Jan 6, and Dec 15. All are a mix of sun crust, surface hoar and facets depending on your aspect and elevation. Avalanches are occurring on these layers and human triggering is likely.
Use conservative route selection, choose supported terrain with low consequence.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 3

Wind Slabs

Recent winds and new snow have formed slabs in leeward areas of alpine and treeline terrain, and caused natural avalanches and small cornice failures. These slabs are starting to bond but can still be triggered and may step down to persistent layers.
If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2