Danger remains elevated as buried weak layers continue to produce large and unnerving avalanches. Stick to small and supported terrain features. Be cautious of areas where the snowpack depth changes rapidly, such as thin and rocky start zones.
Remember that small avalanches may step down to deeper weak layers as southerly winds are expected to build fresh wind slabs.
Low density snow on the surface is available for southerly winds to redistribute into pockets of wind slab in north facing terrain.
Small avalanches in wind loaded features have the potential to step down to deeper weak layers creating larger then expected avalanches.
Two concerning layers are responsible for most of the recent large avalanche activity. A layer of surface hoar, facets and/or a crust from late December is buried 40 to 70 cm deep.
A layer of large and weak facets also sits near the base of the snowpack, buried in November. Recent avalanche activity has occurred on both of these layers, with many avalanches stepping down to the deeper facets.
Although widespread, both layers appear to be most reactive around treeline and lower alpine elevations, in terrain with shallow, variable snow depths.
Numerous large to very large (size 2 to 3) avalanches have been naturally and human triggered over the last week, failing on the weak layers described in the Snowpack Summary, 70 to 200 cm deep. Activity was mostly reported between 1800 m and 2500 m elevation and on all aspects. Check out this recent MIN.
These avalanches continue to indicate that these buried weak layers remain reactive, and are capable of producing large consequential avalanches. Many of these human-triggered avalanches were a surprise to the individuals triggering them.
Please continue to share any observations or photos on the Mountain Information Network.
30-50 cm of low density snow sits at the surface of the snowpack. As southerly winds increase expect wind slabs to build in north facing terrain. New wind slabs may sit over a layer of reactive surface hoar and or crust.
The upper snowpack is generally settled and bonded well, however buried weak layers continue to be a concern, with large and surprising (remote or accidental triggered) avalanche activity reported throughout the last week.
A weak layer of crust, facets and/or surface hoar buried just before Christmas is buried 40-70 cm deep. The lower snowpack is generally weak and facetted with a weak layer of large facets from mid November near the bottom.
Snowpack depths are roughly 150 to 200 cm at treeline.
Wednesday Night
Increasing cloud with moderate southerly winds developing. No snowfall expected. Freezing level below valley bottom.
Thursday
Mostly cloudy with moderate to strong southerly winds. Freezing levels remain below 500 m, alpine highs of -7 °C expected. Scattered flurries possible
Friday
Mostly cloudy. Strong southerly winds ease back to moderate. Light snowfall brings up to 5 cm. Freezing levels peak around 800 m. Alpine highs of -4 °C.
Saturday
Mostly cloudy with moderate southerly winds. Scattered flurries continue. Freezing levels peak around 800 m. Alpine highs of -4 °C.
More details can be found in the Mountain Weather Forecast.
