Avalanche Forecast

Issued: Jan 10th, 2019 4:17PM

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

dsaly, Avalanche Canada

Sea To Sky.

Rising freezing levels will warm the snowpack and stress instabilities. Be alert to changing snow conditions and ready to adjust your travel plans accordingly.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

THURSDAY NIGHT: Flurries, accumulating up to 10 cm. Strong south-southwest wind. Freezing level rising above 1600 m.FRIDAY: Cloudy with isolated flurries, trace to 5 cm accumulation. Moderate south-southwest wind gusting strong. Freezing level rising above 2000 m.SATURDAY: Cloudy with sunny period. Light to moderate south wind. Freezing level above 2000 m.SUNDAY: Mainly cloudy. Light south wind with occasional moderate gusts. Freezing level 2000 m.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

On Thursday morning, loose wet avalanches were reported below 1700 m.Numerous storm slab avalanches to size 2 were triggered by explosives and skiers on Wednesday. Additionally, a large (size 2) cornice failed under the weight of a person. On Monday, Several small wind slabs were triggered by skiers near ridge crest.

Snowpack Summary

35 cm accumulating Thursday morning with 40-50 cm snow since January 7 being redistributed to moderate to strong south winds. Wind and warming temperatures have built storm slabs and cornices. As of Thursday morning, freezing levels were around 1700m, and some areas below 1600 m receiving rain. As freezing levels rise, warming temperatures and rain on snow can rapidly lead to loose wet avalanches.The new snow has buried old wind slabs on a variety of slopes at alpine and treeline elevations. At treeline and below, two weak layers exist in the upper 2 m of the snowpack. 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. There have been no recent reports of avalanches on this layer, but it may still be reactive to heavy loads (such as a cornice fall) in isolated areas.

Problems

Storm Slabs

Storm slabs have developed with recent snow and strong southerly winds. Deeper and more sensitive deposits of snow will be found in wind-loaded terrain: under cornices and roll-overs, cross-loaded areas, and lee terrain features.

Be alert to conditions that change with elevation.If triggered storm slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Loose Wet

Freezing levels are forecasted to rise above 2000 m. The chance for loose, wet avalanches will increase as the snowpack warms.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. Watch for terrain traps where small amounts of snow will acumulate into deep deposits.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Valid until: Jan 11th, 2019 2:00PM