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Avalanche Forecast

Jan 9th, 2019–Jan 10th, 2019
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
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
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: North Columbia.

New snow combined with wind is promoting continued wind slab development in the alpine and treeline.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

WEDNESDAY NIGHT: Mainly cloudy with flurries, accumulation of 5-10 cm, moderate southwest winds, alpine temperature -6 CTHURSDAY: Isolated flurries, moderate southwest winds, alpine temperature -3 C, freezing level 1200mFRIDAY: Cloudy with sunny periods, light to moderate southwest winds, alpine temperature -3 C, freezing level 1300 mSATURDAY: Mix of sun and cloud, light southwest winds, alpine temperature 1 C, possible temperature inversion

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.

Snowpack Summary

Snowfall combined with wind on Wednesday into Thursday will have formed new wind slabs in lee and cross-loaded terrain features at high 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.
Watch out for wind slabs, especially in steep slopes or depressions near ridges.Look for signs of instability such as whumpfs, hollow sounds, shooting cracks, or recent avalanches.Cornices may be touchy; stay well-back on ridges and avoid travelling beneath them.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5