Avalanche Forecast

Issued: Jan 10th, 2019 4:01PM

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

South Coast Inland.

Recent snow and wind have developed slabs. The deepest and most reactive deposits of snow will be found in wind-loaded terrain.

Summary

Confidence

Low - Freezing levels are uncertain

Weather Forecast

THURSDAY NIGHT: Cloudy with scattered flurries, up to 5 cm snow. Moderate south wind gusting strong. Freezing level rising above 1500 m.FRIDAY: Cloudy with isolated flurries. Light south wind gusting to strong. Freezing level rising above 1600, weak inversion.SATURDAY: Mix of sun and cloud. Light to moderate south wind. Freezing level above 2000 m, weak inversion. SUNDAY: Cloudy with sunny periods, Light south wind with moderate gusts. Freezing level 2000 m.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

On Thursday, wind slab avalanches (size 1-1.5) were had released naturally on north-facing alpine terrain.In the neighboring Sea to Sky region loose wet avalanches were reported below 1700 m on Thursday morning. And on Wednesday, numerous storm slab avalanches to size 2 were triggered by explosives and skiers. Additionally, a large (size 2) cornice failed under the weight of a person. In the South Coast Inland, skiers triggered small wind slabs near ridge crest on Monday, but generally little avalanche activity has been reported over the last couple of days.

Snowpack Summary

Approximately 20 cm new snow adds to the previous 100+ cm of settled storm snow. Recent strong winds have redistributed recent snow built wind slabs and cornices on a variety of slopes. New snow has buried older slabs and developed new storm slabs and cornices.Around the Coquihalla, the top 30-40 cm recent snow sits on a thick 10-15 cm crust up to 1550 m. This crust is not found in the north of the region.Professionals continue to monitor two suspicious layers in the mid-pack. A surface hoar layer buried December 26 is down 60-90 cm and has produced harder results in snowpack tests. Down 100-150 cm in a surface hoar and crust layer buried early December. This layer consist of surface hoar (feathery crystals) in sheltered areas and a sun crust on steep south facing slopes. The surface hoar is reported to be most prominent on north and east aspects at treeline, and has been well reported in the southern part of the region in areas like the Coquihalla Summit and Manning Park.In the lower snowpack, a crust/facet (sugar snow) layer may still be reactive to heavy loads such as a cornice fall in isolated areas.

Problems

Storm Slabs

Storm slabs have developed from new snow, wind, and warming that can be triggered by a person. 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.

If triggered the 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: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Rising freezing levels are forecasted. The chance for loose, wet avalanches will increase as the snowpack warms and freezing levels rise into the alpine this weekend.

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: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1 - 2

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