Avalanche Forecast

Unsettled weather continues with light snowfall. Heavier snowfall is forecast for the immediate coast and further up some inlets, but it is looking unlikely that it will push very far inland.

Saturday night: Flurries around 5 cm. Moderate southwest ridgetop wind. Alpine high around -8 °C. Freezing level valley bottom.

Sunday: Snowfall 2-10 cm of snow expected. Moderate to strong south wind. Alpine high around -5 °C. Freezing level rising to 800 m through the day. 

Monday: Snowfall 10-20 cm. Strong southwest wind. Alpine high around -1 °C. Freezing level rising to 1500 m through the day. 

Tuesday: Snowfall 20-40 cm. Strong south wind. Alpine high around -1 °C. Freezing level dropping to 1000 m through the day. 

On Thursday and Friday, northwest of Terrace, large to very large avalanches were being triggered by riders and vehicles. These avalanches:

• had crowns 60-100 cm deep.
• were failing on a layer of fairly large (10 mm), weak, feathery, surface hoar crystals that were buried early in March.
• were occurring mostly on northeast facing slopes around treeline.
• were easily triggered, sometimes remotely and propagating long distances.

Also on Friday, explosive control work near Shames produced large avalanches on an even deeper weak layer, buried in mid February.

40-80cm of recent snow has fallen, with strong southwest winds creating deeper deposits in lee terrain features. Low elevations may hold 10-30 cm of wet/moist snow sitting over a widespread crust on all aspects below 1200 m.

50-100 cm below the snow surface, a weak layer of feathery surface hoar crystals could be preserved in sheltered terrain at and above treeline. This weak layer has started producing large avalanches, mostly north and west of Terrace, where moderate to heavy snowfall and wind have continued through the week. In areas further inland, where the storm tapered off earlier, this layer may not be at its tipping point, but I'd still be suspicious of it through the weekend. 

A thick rain crust from mid-February is buried 100-150 cm. The snowpack below is well consolidated.

• Uncertainty is best managed through conservative terrain choices at this time.
• Be aware of the potential for remote triggering and large, deep avalanches due to the presence of buried surface hoar.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Caution around convexities or sharp changes in terrain.
• Be careful as you transition into wind affected terrain.