Avalanche Forecast

Issued: Jan 1st, 2018 6:18PM

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

ghelgeson, Avalanche Canada

Sea To Sky.

Continued warm temperatures should allow the snowpack to further settle and stabilize, but small storm slabs in more extreme terrain may still be an issue. Watch for the odd loose wet avalanche on steep solar aspects in the afternoon too.

Summary

Confidence

High -

Weather Forecast

This week will see a complete reversal in the weather pattern as warmer temperatures and dry conditions are expected to dominate. Warmer air aloft will prevail as an off shore upper ridge pushes inland and the flow aloft switches from cold northwesterly to mild southwesterly. This warm dry period is expected to persist through Friday.TUESDAY: A few clouds in the morning, cloud cover increasing to broken by the afternoon, Freezing level around 2700 m, light southwest wind, no snow expected.WEDNESDAY: Clear skies, freezing level around 2500 m, light southwest wind, no snow expected.THURSDAY: Broken cloud cover, freezing level around 2000 m, light southwest wind, no snow expected.

Avalanche Summary

On Monday several loose wet avalanches to size 1 were reported from southeast and south facing features between 1800 and 2100 m. On Sunday there was one report of a size 2.5 natural avalanche on a steep east facing feature in the alpine. There was also a small skier triggered avalanche on a southeast facing moraine feature at 1800 m. Loose dry avalanches to size 1 were reported from a variety of aspects.

Snowpack Summary

On Sunday a slight crust began to form on south and southwest facing aspects as warm temperatures and sun combined to moisten the snow surface. Cooler north and east facing features remain cold and dry. Last Thursday and Friday two successive storms produced 50 to 70 cm of snow with wind mainly out of the south. The new snow rests on a variety of old surfaces including crust on solar aspects, old wind slabs, facets and isolated surface hoar below treeline, but avalanche activity on this interface continues to decrease as time and warm temperatures allow the old storm snow to settle and gain cohesion. Wind effect in the alpine has been widely reported but wind slab activity has been limited.40 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

Aided by wind, time and warmth, the storm snow is settling into a more cohesive slab. For the most part, this slab is bonding well to the underlying surface, but don't be too cavalier with your decision making, warming temps may change its behavior.

Caution with wind slabs, especially in steep, unsupported and/or convex terrain features.Storm slabs could become more sensitive to human triggering as alpine temps approach +5 C Tuesday.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Loose Wet

Natural loose wet avalanches remain possible Tuesday, especially on steep sun exposed slopes. With all the new snow in the last few days, loose wet avalanches could entrain considerable mass, especially in terrain traps like gulleys.

Minimize exposure to solar aspects overhead, loose avalanches could travel surprisingly far.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Avoid sun exposed slopes especially if the snow is moist or wet.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 2nd, 2018 2:00PM