Avalanche Forecast

Issued: Jan 14th, 2019 4:42PM

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

dsaly, Avalanche Canada

Sea To Sky.

The battle between winter and spring continues. A warm snowpack can weaken quickly, use caution around cornices and steep slopes until temperatures drop.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

MONDAY NIGHT: Clear. Freezing level dropping below 1000 m, temperature inversion. Alpine low near +1. Light winds. TUESDAY: Sunny and warm. Freezing level near 1900 m. Alpine high near +4. Light winds. WEDNESDAY: Mix of sun and cloud. Freezing level below 1600 m. Alpine high near 0. Light winds. THURSDAY: Cloudy with isolated flurries, up to 10 cm. Freezing level 1400m. Alpine high near -1. Light to moderate east winds.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

Several large cornice falls were triggered naturally and with explosives on Saturday. Some of these triggered size 2 slabs on slopes below. There is a trend of cornice falls increasing in size and frequency as the warm weather continues. Loose wet avalanches to size 2 were also failing naturally on sunny aspects on Saturday with continued reports into Sunday.On Sunday, three very large (size 3) slab avalanches were reported in the region. These avalanches occurred around 1500-1900 m and two of these avalanches were observed on south-south east aspects. It is likely that that solar warming and sluffing triggered these avalanches Friday or Saturday.

Snowpack Summary

Warm temperatures are weakening surface snow layers has made cornices extra touchy. The warmth can also penetrate into more deeply buried weak layers. Minimal overnight freeze is expected, meaning warming is likely to affect the snowpack early in the day.Refrozen crusts may be found on all aspects below about 1800-2000 m; and on sunny aspects in the alpine in some places. These may break down through the day. Cold, dry and possibly wind-affected snow may still be found on various aspects in the alpine. Variable instabilities exist in recent storm snow layers. Two weak layers exist in the upper 2 m of the snowpack at and below treeline. These layers consist of surface hoar (feathery crystals) in more sheltered areas and a crust on solar aspects and on all aspects below 1600m.In the lower snowpack, a crust/facet (sugar snow) layer is now over 2 m deep. This layer may still be reactive to heavy loads (such as a cornice fall) in isolated areas.

Problems

Cornices

Cornices can weaken quickly with warming, and can act as triggers for avalanches on the slope below.

Minimize exposure to cornices overhead and stay well back on ridges.Be aware of the potential for very large avalanches du to a deeply buried weak layer.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Loose Wet

Sun and warm temperatures are causing loose wet and wet slab avalanche conditions. Look for clues like sticky snow, rollerballing or recent avalanche activity, that indicate the snowpack is losing strength.

Watch for terrain traps where small amounts of snow will acumulate into deep deposits.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 2

Valid until: Jan 15th, 2019 2:00PM