Avalanche Forecast

The frontal system drifts south on Tuesday night, leaving a lull before the next storm arrives Thursday morning...

TUESDAY NIGHT: 5-15 cm of snow, strong northwest wind, freezing level drops to valley bottom with alpine temperatures around -6 C.

WEDNESDAY: Mostly cloudy with some isolated flurries and trace accumulations, moderate west wind, freezing level climbs to 500 m with alpine high temperatures around -4 C.

THURSDAY: The next storm brings 20-40 cm of snow, strong to extreme wind from the south, freezing level climbs to 800 m with alpine high temperatures around -3 C.

FRIDAY: Scattered flurries with 5-10 cm of snow, light to moderate snow from the south, alpine high temperatures around -5 C.

A steady pulse of storms over the past week has produced numerous cycles of large natural avalanches. These avalanches have failed on a mix of storm interfaces and persistent weak layers. The most recent cycle will likely occur at higher elevations on Tuesday night, leaving storm slabs primed for human triggering on Wednesday.

Reports from Monday include several natural (size 2) storm slab avalanches, some of which were observed on open rollovers at treeline which likely failed on the March 1 surface hoar layer. On Friday and Saturday there were reports of natural and skier triggered size 2-3 avalanches failing on the February 19 surface hoar layer, primarily on north and east facing slopes around treeline.

There have also been some isolated reports of very large (size 2.5-2.5) natural and explosive triggered avalanches on deeper weak layers (including one on March 1 that failed on the January facet layer on a northeast slope at 1500 m near Kitimat and a few on March 2 that failed on basal facets on east and southeast alpine slopes near Ningunsaw).

Large cornice and glide crack failures continue to be reported too.  

New storm slabs will continue to form throughout the week with significant snow and wind in the forecast. There will be a lull between storms on Wednesday, but 15-30 cm of fresh snow snow from Tuesday will leave widespread and reactive storm slabs, especially on wind loaded slopes.

Recent storms have buried two layers of surface hoar that continue to be reactive and produce large avalanches. One layer was buried on March 1st and is currently 30-60 cm below the surface, the other was buried on February 19th and is currently 75-125 cm below the surface. On solar aspects (south through west) surface hoar may be resting on a buried crust which could be a very problematic setup. A rain crust can be found up to roughly 1000 m, but you should be very suspect of slopes at treeline elevations and at the higher end of below treeline where preserved surface hoar most likely exists.

A layer of weak and sugary faceted grains that formed in January may be found about 120 to 170 cm deep, and an early-season melt-freeze crust linger at the base of the snowpack. These layers have produced a few very large natural and explosive triggered avalanches over the past two weeks.

• Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
• Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
• Avoid travelling on slopes below cornices.
• Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.