Avalanche Forecast

Issued: Jan 5th, 2018 5:16PM

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

Avalanche Canada ghelgeson, Avalanche Canada

Wind stiffened storm slabs are expected to form Friday night into Saturday at upper elevations. These slabs may be resting on a slight crust which could make them that much more sensitive to human triggering.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Saturday

Weather Forecast

Rain is expected to turn to snow Friday night as the freezing level lowers and a couple of weak residual lows bring patchy light precipitation to the coast through the weekend.FRIDAY NIGHT: Freezing level beginning around 1800 m, lowering to 1500 m by dawn, moderate southwest/west wind, 5 to 15 cm of snow expected at upper elevations.SATURDAY: Overcast, freezing level around 1400 m, light to moderate south/southeast wind, 1 to 5 mm of precipitation expected.SUNDAY: High cloud, freezing level around 800 m, light south wind, 1 to 3 mm of precipitation expected.MONDAY: High cloud, freezing level around 900 m, light south wind, 3 to 6 mm of precipitation expected.

Avalanche Summary

On Friday several loose wet avalanches released naturally below 2000 m in elevation. Professionals conducting control work were able to ski cut avalanches to size 1.5 in the alpine. Snowballing and pinwheeling from steep rocky terrain was also observed.

Snowpack Summary

Rain Friday reportedly soaked the upper 15 to 20 cm of the snowpack and left all aspects with moist snow on the surface from valley bottom to at least 2000 m, maybe even ridgetop. As temperatures begin to cool Friday night we can expect a thin melt freeze crust to form on the surface. New snow and wind Friday night into Saturday will likely allow for the formation of fresh storm slabs on this crust at upper elevations.Up to 100 cm below the surface there is a widespread melt-freeze crust that was buried on December 15th. This layer has not produced much in the way of avalanche activity and is likely trending towards dormancy. Beneath the mid-December crust, the lower snowpack is generally strong and well settled.

Problems

Storm Slabs

An icon showing Storm Slabs
Light snowfall coupled with moderate winds out of the southwest will likely result in wind stiffened storm slabs at upper elevations Saturday. These wind slabs may be sitting on a thin crust which may increase their sensitivity to human triggering.
Use ridges or ribs to avoid pockets of wind loaded snow.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Storm slabs may become more sensitive to human triggering throughout the day.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 6th, 2018 2:00PM