Avalanche Forecast
Northwest Coastal
An persistent weak layer buried earlier this month has woken up. The consequences of triggering this layer could be very high. Time to step back and stick to supported terrain.
Avalanche Problem 1: Persistent Slabs
What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?
Travel and Terrain Advice
- Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.
- Use extra caution around steep rolls and sheltered openings where surface hoar may be preserved.
- Be aware of the potential for loose dry avalanches in steep terrain where snow hasn't formed a slab
Avalanche Problem 2: Wind Slabs
What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?
Another short pulse of new snow and wind is set to fuel wind slab formation at higher elevations. Very large avalanches may result if shallower slabs step down to our buried weak layers.
Travel and Terrain Advice
- Be especially careful with wind loaded pockets near ridge crests and roll-overs.
- Watch for signs of instability such as shooting cracks or recent avalanches.
Avalanche Summary
Reports from Tuesday showed numerous large (size 2-3) persistent slabs releasing with remote (from a distance) triggering over a layer of surface hoar buried 40-60 cm deep in the Terrace area. This activity was focused on shaded aspects at treeline and below.
There was a report of a small (size 1) skier-triggered storm slab on Sunday that occurred on a north aspect at 1400 metres. The slab was 40 cm deep and failed on a more recently buried layer of surface hoar. Numerous natural wind slab and storm slab releases from size 1.5-2.5 were observed from the highway in Bear Pass. Poor visibility had been noted for limiting observations throughout the region.
Reports from Saturday showed ski cutting in the Bear Pass area producing both slab and loose dry avalanches to size 1.5. Slabs failed all the way down to the melt-freeze crust buried 60 cm deep at treeline on north aspects.
Snowpack Summary
Stormy weather brought 50-80 cm of new snow to the region over the past week. These accumulations taper quickly at lower elevations as well as moving inland from the coast. Strong southwest to northwest winds have been redistributing the new snow into wind slabs at high elevations. Beneath the wind effect, the storm snow overlies old surfaces that include a layer of surface hoar on high shaded aspects as well as a melt-freeze crust on all aspects at treeline and below.
Another lingering layer of surface hoar can be found just below the first on shaded aspects at lower elevations. With the overlying storm snow now settled into a stiffer slab, this layer became touchy in the Terrace area on Tuesday, producing numerous large, remotely-triggered avalanches.
Deeper in the mid-pack, layers of crusts, facets, and isolated surface hoar buried 50 to 100 cm exist from mid- and late-February and a surface hoar/ crust layer from January is buried around 150 to 200 cm. Near the bottom of the snowpack, sugary facets exist in colder and dryer parts of the region, such as the far north. These buried layers are currently dormant.
Weather Forecast
Thursday: Cloudy with flurries bringing 10-15 cm of new snow, continuing overnight. Moderate to strong south winds. Freezing level to 700 metres with alpine high temperatures around -4.
Friday: Mainly cloudy with continuing isolated flurries and a trace of new snow. Light northwest winds. Freezing level to 700 metres with alpine high temperatures around -5.
Saturday: A mix of sun and cloud. Light southeast winds. Freezing level to 800 metres with alpine high temperatures around - 3.
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We have reports of a deeply buried layer of surface hoar becoming very reactive on shaded slopes at treeline and below in the Terrace area. Numerous large (size 2-3) persistent slabs have been remotely triggered, with slab depths of up to 60 cm.