Archived

Avalanche Forecast

Jan 28th, 2018–Jan 29th, 2018

Alpine

4: High

The avalanche danger rating in the alpine will be high

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

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

Regions: South Coast.

Rain will bring loose wet avalanche problems to the fore on Monday. Thick storm slabs may continue to build at high alpine elevations.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Sunday night: Heavy rain, 40-60mm accumulation. Heavy snow accumulation possible at high alpine elevations. Strong to extreme south winds. Monday: Cloudy with continuing heavy rain below about 1600 metres. 40-50mm accumulation. 30-40 cm of new snow possible at high alpine elevations. Strong to extreme southwest winds. Freezing level to 2000 metres with alpine high temperatures around 0 to +1.Tuesday: Cloudy with continuing flurries bringing 10-20 cm of new snow. Moderate southwest winds. Freezing level to 900 metres with alpine high temperatures of -3.Wednesday: Mainly cloudy with isolated flurries and a trace of new snow. Light west winds. Freezing level to 800 metres with alpine temperatures of -4.

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 Size 1.5 storm slab that released from steeper pitch below treeline. The remaining party members performed a rapid companion rescue and no injuries were sustained by anyone involved. 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 see rain falling on dry snow are expected to undergo a natural avalanche cycle over Sunday night into Monday. Areas that experience precipitation falling as snow will see rapid formation of touchy new storm slabs over the same time period.

Snowpack Summary

Heavy rainfall is set to soak the upper snowpack at most elevations over Sunday night and Monday. High alpine elevations in areas like Sky Pilot and the Chehalis Range may see thick new storm slabs develop over the same time period. Below these variable surface conditions, storm snow totals from the past week have reached 110-180 cm and strong southerly ridgetop winds during the storm have been redistibuting each day's snow into storm slabs at all elevations. The touchiest conditions will be likely to exist in exposed, higher elevation terrain, however heavy rain may also destabilize more recent storm slabs at lower elevations and will certainly promote loose wet avalanches in steeper terrain. The crust that exists beneath all our recent snow accumulations is likely to have now formed a solid bond to the overlying snow.

Avalanche Problems

Loose Wet

Heavy rain will continue to saturate our recent storm snow and promote loose wet avalanches at all but the highest alpine elevations. This may occur naturally or with a human trigger - especially in steep terrain.

Avoid gully features.Use extra caution on slopes if the snow is moist or wet.Watch for terrain traps where loose wet releases might accumulate into deep deposits.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 2.5

Storm Slabs

Heavy snowfall and strong winds are likely to create touchy new storm slabs in the alpine over Sunday night and Monday. Ongoing heavy rain may act as a trigger for less recent storm slabs at lower elevations.

Avoid avalanche terrain during periods of heavy loading from new snow, wind, or rain.The new snow will need time to settle and stabilize.Be alert to conditions that change with elevation.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2

Cornices

Large amounts of recent new snow and high winds have been creating rapid cornice growth. Continuing snow and rain will destabilize cornices further.

Give cornices a wide berth when travelling on or below ridges.Falling cornices may trigger large avalanches on slopes below.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1.5 - 2.5