Avalanche Forecast

Issued: Jan 30th, 2018 5:53PM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Storm Slabs and Cornices.

Avalanche Canada cgarritty, Avalanche Canada

Avalanche danger will rise in sync with new snow accumulations. Watch for both to increase over the day on Wednesday.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Wednesday: Cloudy with flurries bringing approximately 5 cm of new snow, increasing overnight. Light to moderate south winds. Freezing level to 600 metres with alpine temperatures around -4.Thursday: Cloudy with continuing flurries bringing approximately 5cm of new snow over the day, increasing overnight. Light to moderate southwest winds, increasing overnight. Freezing level to 800 metres with alpine temperatures of -3.Friday: Cloudy with continuing flurries bringing approximately 5 cm of new snow to high elevations. Light rain below about 1000 metres. Moderate southwest winds. Freezing level to 1500 metres with alpine temperatures around -1 to 0.

Avalanche Summary

Reports from Saturday included one MIN submission detailing a near miss incident involving several members of a ski touring party on Hollyburn Mountain. Two skiers were partially buried and one was fully buried in a large storm slab that released from a steeper pitch below treeline. Please see the MIN submission for details. Other MIN reports from the region over the past two days have shown ski cutting easily producing storm slab results at the depth of each day's accumulations.Looking forward, areas that experienced heavy rain should see the snowpack quickly stabilize as temperatures cool. With that said, new snow that accumulates on this refreezing surface will likely form unstable new storm slabs before the new snow has a chance to form a solid bond. High alpine areas that haven't seen rain are on a different trajectory. Here, recently formed storm slabs will need more time to stabilize as they experience continued loading from new snow and wind.

Snowpack Summary

Light new snow amounts have begun to accummulate on the refrozen snow surface after heavy rainfall soaked the upper snowpack at most elevations over Sunday night and Monday. High alpine elevations in areas like Sky Pilot and the Chehalis Range may have seen thick new storm slabs develop over the same time period. Below these elevation-dependant surface conditions, storm snow totals from the past week reached 110-180 cm. The crust that exists beneath these recent snow accumulations is expected to have formed a solid bond to the overlying snow.

Problems

Storm Slabs

An icon showing Storm Slabs
Recent heavy snowfall and strong winds formed thick storm slabs in high alpine terrain. They should be on a stabilizing trend, but may remain reactive to human triggering in steep, unsupported terrain and convex features.
Use ridges or ribs to avoid pockets of wind loaded snow.Evaluate unsupported slopes critically.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2.5

Cornices

An icon showing Cornices
Recent heavy snowfall and high winds have created fragile new cornice growth.
Give cornices a wide berth when travelling on or below ridges.Falling cornices may trigger avalanches on slopes below.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Jan 31st, 2018 2:00PM