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Avalanche Forecast

Jan 10th, 2019–Jan 11th, 2019
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: North Columbia.

Warming this weekend will elevate the avalanche danger. Pay particular attention to sun affected slopes.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

THURSDAY NIGHT: Dry, cooling overnight.FRIDAY: Dry with a mix of sun and cloud. Freezing levels rising to around 1500 m. Alpine temperatures around -2C. Light southerly winds.SATURDAY: Dry and sunny. Inverted conditions with an above freezing layer between 1800m and 2400m. Light southerly winds.SUNDAY: Dry and sunny. Inverted conditions with an above freezing layer between 1800m and 2400m. Light southwesterly winds.

Avalanche Summary

A size 3-3.5 persistent slab avalanche was skier triggered on the north side of the highway in Glacier National Park on Tuesday. This was triggered from a thin spot on the ridge at 2250 m on a south east aspect It ran to the valley bottom and is suspected to have run on a layer of surface hoar sitting on a crust that was buried in late November. See the MIN post here. The onset of warmer weather may increase the likelihood of triggering a large avalanche.

Snowpack Summary

Although the recent new snow has now ended, wind slabs are likely still reactive in lee and cross-loaded terrain features at higher elevations. This new snow has fallen on widespread wind-affected snow at alpine and treeline elevations. Below this, the snowpack is generally well-settled. There is however, a layer of feathery surface hoar that is sitting on a crust that was buried late November down 100-200 cm. This crust is suspected to be the bed surface for few very large avalanches over the past several days on southwest through southeast aspects in this region.

Avalanche Problems

Wind Slabs

New snow and wind have promoted new wind slab formation. Use added caution in lee and cross-loaded terrain features near ridges.
Cornices may be touchy; stay well-back on ridges and avoid travelling beneath them.Look for signs of instability such as whumpfs, hollow sounds, shooting cracks, or recent avalanches.Watch out for wind slabs, especially in steep slopes or depressions near ridges.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Persistent Slabs

There have been a few recent avalanches on deeper layers in the snowpack. The likelihood of triggering a deeper layer will increase with anticipated warm weather.
Be aware of thin areas that may propogate to deeper instabilites.Warm weather will increase the chance of triggering a deeper layer.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2.5 - 3.5