6:30 AM PST UPDATE: A weak layer of surface hoar is buried at a prime depth for human-triggering as well as large consequential avalanches.
The most activity has been noted on northerly alpine slopes, but until we gain more information about this layer riders should take a very cautious approach to avalanche terrain. Check out this MIN report from the Avalanche Canada field team on Friday.
Be wary of isolated pockets of surface hoar buried by stiff wind slabs, in wind loaded, northeasterly alpine terrain. Recent avalanches have shown an impressive capability to propagate.
A weak layer of surface hoar overlying a crust is now buried 50-100 cm deep, a prime depth for human-triggering and large consequential avalanches. The most activity has been noted on northerly alpine slopes, but until we gain more information about this layer riders should take a cautious approach to avalanche terrain. Keep in the mind the potential for remotely triggered avalanches.
Numerous large (size 2-3) natural and human-triggered persistent slab avalanches have been reported in the past 3 days. These avalanches are failing on a weak layer of surface hoar with a crust below.
In alpine terrain, recent winds have created a variety of wind-affected surfaces. Wind slabs remain in steep, lee terrain features and may be burying isolated pockets of preserved surface hoar. The surface hoar is reported to be roughly 50 to 80 cm down from the surface. Below roughly 1700 m a widespread, melt-freeze crust is present, with moist snow below.
Sunday night
Becoming overcast, with flurries beginning in the early morning. Treeline temperatures -5 to -10 C. Moderate west alpine winds.
Monday
Cloudy, with flurries, 0 to 2 cm. Treeline temperatures -5 to -10 C. Moderate westerly alpine winds.
Tuesday
Cloudy, with flurries, 0 to 2 cm. Treeline temperatures -5 to -10 C. Light southwest alpine winds.
Wednesday
Cloudy with sunny periods, no precipitation. Treeline temperature -10 to -15 C. Moderate alpine winds.
More details can be found in the Mountain Weather Forecast.
