Avalanche Forecast

Issued: Jan 22nd, 2020 4:00PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs, Deep Persistent Slabs and Loose Wet.

Avalanche Canada shorton, Avalanche Canada

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An intense storm will create very dangerous avalanche conditions on Thursday.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain. Uncertainty is due to extremely variable snowpack conditions reported through the region.

Weather Forecast

WEDNESDAY NIGHT: Frontal system arrives overnight with 10-15 cm of snow above 1700 m, strong wind from the southwest, alpine temperatures rise to -2 C.

THURSDAY: Heavy snowfall in the south of the region (20-40 cm) and moderate to heavy snowfall in the north (15-25 cm), rain below 1500 m, strong wind from the southwest, alpine high temperatures around -1 C.

FRIDAY: Another 5-15 cm of snow, moderate wind from the southwest, alpine high temperatures around -3 C.

SATURDAY: Cloudy with some light flurries, light wind from the southwest, alpine high temperatures around -3 C.

Avalanche Summary

The incoming storm will increase the likelihood of storm slab, deep persistent slab, and wet loose avalanches. In the past few days there have been a few reports of small (size 1) slab avalanches in the northern part of the region and wet loose avalanches around the Coquihalla.

Snowpack Summary

New snow will accumulate above 1500 m creating new storm and wind slabs. The new snow is burying a mix of old wind slabs, crusts, and moist snow.

There are currently no concerns about deep weak layers in the south of the region (e.g. Coquihalla).

There have been two layers of concern in the northern half of the region (e.g. Duffey, Hurley). One is a weak layer of surface hoar buried about 100 cm deep that professionals are tracking at treeline in sheltered areas. The other is weak faceted grains and crusts near the bottom of the snowpack, that is most likely to be triggered in shallow rocky start zones.

Terrain and Travel

  • Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
  • Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.

Problems

Storm Slabs

An icon showing Storm Slabs

Heavy snowfall, strong wind, and warm temperatures will cause a natural cycle of large storm slab avalanches on Thursday.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Weak layers in the northern part of the region will be stressed by the storm, increasing the likelihood of large deep persistent slab avalanches. Two layers have been a concern in the north including a 100 cm deep surface hoar layer in sheltered areas around treeline and weak snow near the bottom of the snowpack in shallow rocky start zones at higher elevations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Loose Wet

An icon showing Loose Wet

Rain at lower elevations may cause wet loose avalanches in steep terrain.

Aspects: All aspects.

Elevations: Below Treeline.

Likelihood

Possible

Expected Size

1 - 2

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