Avalanche Forecast

Issued: Dec 16th, 2017 5:10PM

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

ghelgeson, Avalanche Canada

Northwest Inland.

Plan to avoid potentially wind loaded slopes just below ridge crest and areas with a thin or variable snowpack, especially if you are traveling in the alpine.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

A frontal system is currently impacting the coast, and some spill over into the Inland region is probable. Light precipitation and strong southwest wind is expected through Saturday night. Snow and wind, albeit modest in quantity, is expected on Sunday and Monday before the ridge rebounds on Tuesday giving way to a cool dry pattern.SATURDAY NIGHT: Freezing level falling from 1400m down to around 600m through the night. 5 to 10cm of snow possible, strong to extreme southwest wind.SUNDAY: Broken cloud cover, freezing level around 500m, moderate to strong west/southwest wind, trace to 5cm of snow possible.MONDAY: Scattered cloud cover, freezing level near valley bottom, moderate to strong southwest wind, trace to 5cm of snow possible. TUESDAY: Scattered cloud cover, freezing level at valley bottom, light variable wind, no new snow expected.Visit avalanche.ca/weather for a more detailed mountain weather forecast.

Avalanche Summary

No recent avalanche observations. Please submit your information to the Mountain Information Network.

Snowpack Summary

5cm of new snow fell Friday night into Saturday accompanied by moderate to strong southwest wind. This new snow rests on a wide variety of old surfaces including solar and temperature crusts on sun-exposed slopes and stiff, stubborn wind slabs in leeward alpine terrain. Feathery surface hoar and surface facets previously formed below treeline from valley bottom up to around 1500m. Approximately 30 to 50cm of snow sits on two crusts that were buried near the end of November. These crusts are widespread and extend into the alpine. Although snowpack tests have previously shown hard results at these crust interfaces, more recent observations have been limited. Below these crusts, a well settled mid-pack overlies the late October crust near the base of the snowpack. This "crust/facet combo" layer is widespread and has not been reactive to rider and remote triggers since the end of November. These rain crusts will likely be with us all winter but may not pose a problem until we see a significant change in the weather.Average snowpack depths now total 80-140 cm at treeline elevations and up to 160 cm in the alpine.

Problems

Wind Slabs

These wind slabs are most likely to be found immediately lee of ridge crest and around mid-slope terrain features like rock outcroppings. While relatively small, these could be problematic in complex terrain.

Be cautious as you transition into wind affected terrain.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The late October crust lies near the base of the snowpack with a thin layer of weak, sugary snow above it. This layer should be gaining strength, but a heavy trigger in a thin snowpack area could initiate a failure and subsequent large avalanche.

Be especially cautious in shallow snowpack areas where triggering a deeper layer may be easier.Be aware of the possibility for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Dec 17th, 2017 2:00PM