Avalanche Forecast

Wednesday night: Clearing. Moderate northerly wind. Alpine temperatures around -7. Freezing level valley bottom.

Thursday: Mix of sun and cloud. Northwest wind increasing to strong. Alpine high temperatures around -6. Freezing level 900 m.

Friday: Mostly cloudy. Strong northwest wind shifting southwest. Alpine high temperatures around -5. Freezing level 1000 m.

Saturday: Mostly cloudy. Strong southwest wind. Alpine high temperatures around -5. Freezing level 1000 m.

We are still awaiting observations of avalanche activity during and since the storm. Observations from Tuesday were mostly from below treeline, due to poor visibility at higher elevations.

• Debris from a size 2 storm slab was observed mid path in the CN corridor west of Terrace. 
• Natural loose wet avalanches size 1-1.5 were observed below treeline throughout the region.
• In the north of the region, low elevation explosive control work produced a few size 1.5-2.5 loose wet and storm slabs, the largest of which ran on a crust buried in mid March.

Reports from Monday:

• At Shames, a skier accidentally triggered a storm slab size 1.5 on a northwest aspect around 1400 m.
• East of Kitimat, a natural cornice-triggered wind slab size 2 on an east aspect around 1000m. Crown depth ranged from 70 cm up to 2 m. The failure plane is suspected to be a layer of surface hoar buried in early March.
• Along the CN corridor west of Terrace, low elevation loose wet and wet slabs ran naturally size 1.5-2
• Also along the CN corridor west of Terrace, several natural glide slabs were observed size 2-3. This serves as a great reminder to avoid slopes with glide cracks on them at all times. They are inherently unstable and can release at any time.

Tuesday's storm dropped 30-50 cm of new snow over the region, depth varying with elevation. After a lull toward the end of the storm, wind is forecast to pick up again from the northwest on Thursday, likely building deep slabs in lee terrain features at upper elevations.

A crust is buried 60-80 cm below the surface on solar aspects and below 1400 m. At higher elevations where this crust tapers out, the new snow has added significant load to a couple of deeply buried weak layers that we haven't quite ruled out as problems.

The first and most concerning is a roughly 70-100 cm-deep persistent weak layer of surface hoar buried March 12 on sheltered northerly aspects around treeline. Deeper down, around 100 to 300 cm now overlies another layer of surface hoar (and faceted snow) buried in mid-February that may still be a concern in shallower snowpack areas. Although they haven't produced recent avalanches, professionals in the region have been tracking and treating these layers with caution. If it hasn't already been occurring, there is a chance further loading during Tuesday's storm could result in some step-down activity to produce very large and destructive avalanches.

The mid and lower snowpack is well settled and strong in most areas.

• The new snow may require another day to settle and stabilize.
• Even brief periods of direct sun could produce natural avalanches.
• Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
• Seek out sheltered terrain where new snow hasn't been wind-affected.
• Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.