Avalanche Forecast

Issued: Dec 28th, 2017 5:09PM

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

ghelgeson, Avalanche Canada

Sea To Sky.

Natural avalanche activity is expected to tapper off early Friday morning, but human triggered avalanches remain possible or even likely in wind loaded features, especially those that are steep and unsupported.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

Most of BC finds itself under the influence of a massive arctic high-pressure system that has enveloped the province in an unseasonably cold, dry arctic air mass. In contrast, a milder, moisture-laden stream of air has taken aim at southwestern BC. These two air masses are set to clash over southern BC through Friday night, producing potentially heavy snowfall along the south coast before expected clearing begins on Saturday.THURSDAY NIGHT: Freezing level at valley bottom, moderate to strong west wind, 1 to 5 cm of snow possible. FRIDAY: Overcast, freezing level at valley bottom, light to moderate southwest wind, trace of snow possible. FRIDAY NIGHT: Freezing level at valley bottom, 5 to 30 cm of snow possible. SATURDAY: Skies clearing throughout the day, freezing level at valley bottom, light to moderate NW wind, no snow expected.SUNDAY: Clear skies, freezing level at valley bottom, light variable wind, no snow expected.

Avalanche Summary

On Wednesday small loose dry avalanches were reported running in steep terrain features. Control work on Thursday produced soft storm slabs to size 1 in the alpine with crowns up to 45cm in depth. Natural avalanches to size 1 were also observed.

Snowpack Summary

As of Thursday afternoon the region has picked up 10 to 30 cm of new snow accompanied by moderate to strong winds out of the south/southwest. Snowfall is expected to continue through Thursday night. The new snow covers a medley of old surfaces which include stubborn wind slabs and wind-scoured exposed crust in the alpine, and soft unconsolidated snow in sheltered areas at treeline and below. Up to 60 cm below the surface you'll likely find a widespread melt-freeze crust that was buried on December 15th. This layer has not produced much in the way of avalanche activity, but could come to life with the additional load of new snowfall, especially in areas where loose facets exist above the crust.Beneath the December 15th layer, the lower snowpack is generally strong and well settled.

Problems

Storm Slabs

A brief break in the storm cycle Friday should begin to reduce the likelihood of human triggered avalanches, but you need to remain vigilant in your travel practices, especially when it comes to convexities, terrain traps and wind loaded slopes.

Use caution in lee alpine and treeline terrain where human triggering is most likely.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Use caution above cliffs and terrain traps where small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 29th, 2017 2:00PM