Avalanche Forecast

Issued: Jan 11th, 2019 4:21PM

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

dsaly, Avalanche Canada

South Coast Inland.

How warm will it get? A rapidly warming snowpack can quickly lose strength and stress buried instabilities. Best to choose conservative terrain and be aware that conditions may deteriorate through the day limiting your exit plans.

Summary

Confidence

Low - Freezing levels are uncertain

Weather Forecast

FRIDAY NIGHT: Partly cloudy. Light south-southeast wind gusting moderate. Alpine temps reaching +1C, freezing level rising above 1000 m, weak temperature inversion.SATURDAY: Mix of sun and cloud. Light southeast wind gusting strong. Alpine temps reaching +2, freezing level above 2000 m.SUNDAY: Cloudy with sunny periods. Light south-southeast wind with moderate gusts. Alpine temps reaching +4C, freezing level 2000 m.MONDAY: Mix of sun and cloud. Light mostly south variable wind. Alpine temps reaching +6, freezing level above 2500 m, alpine temperature inversion.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

On Thursday, a recent natural wind slab avalanches to size 1.5 were observed on wind-loaded and cross-loaded terrain.On Thursday morning in the neighboring Sea to Sky region, a natural storm slab avalanche cycle size 2-3 was reported on rocky features around 2000 m and loose wet avalanches were observed below 1700 m. Explosives triggered numerous size 1-2 storm slabs with good propagation across features.

Snowpack Summary

Warming temperatures and moderate to strong south winds have have redistributed recent snow and promoted settlement. Freezing levels pushed above 1600 m on Thursday with no overnight recovery into Friday. 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 70-100 cm and has produced harder results in snowpack tests. Down 120-150 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

Loose Wet

A major input of heat into the snowpack can stress deeper instabilities and activate buried weak layers. Use caution as the snowpack responds to the initial punch of rapid warming and spiking freezing levels.

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

Expected Size

1 - 2

Storm Slabs

Storm slabs have developed from new snow, wind, and warming that can be triggered by a person. Southerly winds have redistributed snow. Deeper and more sensitive deposits of snow will be found in lee features and cross-loaded 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: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 12th, 2019 2:00PM