Weekend snowfall has produced storm slabs in sheltered areas and wind slabs at higher elevations
Monday brings a warming trend that will increase avalanche hazard.
Three weak layers are buried at a prime depth for human triggering within the top metre of the snowpack. The likelihood of triggering these layers may increase with warming temperatures.
Fresh low density snow is sitting on a variety of weak surfaces that were formed during this past week's cold spell.
Weekend storm snow has been redistributed at higher elevation. Southwest winds will have likely developed wind slabs and they will be thickest and touchiest in lee terrain features.
A warming trend starting late Sunday evening will increase reactivity.
Avalanche activity has increased substantially over the weekend producing numerous small and large-scale avalanches. Most of this cycle has been natural but has also been human triggered. Storm slabs have been the main concern but persistent slabs are still produced and an increase in wind and temperature has been promoting wind slabs as well. With Monday's rising temperatures, avalanche activity is expected to continue.
Accumulated weekend snowfall will vary in depth throughout the region with most areas receiving 50 to 60 cm and some getting as much as 90 cm. South southwest winds will likely redistribute this into wind slabs at higher elevations. In more sheltered areas the recent snow will have formed a storm slab. A warmer trend starting Sunday night and continuing into Monday is expected to promote the formation of these slabs. The new snow may not bond well to the variety of surfaces that it overlays. These include hard wind-packed snow in exposed alpine, crust on steep sun-exposed slopes, small surface hoar crystals in wind-sheltered areas, and sugary facet crystals in other areas.
Numerous other problematic layers exist in the top 50 to 100 cm of the snowpack, consisting of surface hoar, faceted grains, and/or a crust. Avalanches have been most prominent between 1700 and 2200 m and on all aspects. Read our forecaster blog for managing a persistent slab problem.
Sunday Night
Cloudy, up to 7 cm accumulation, 25 to 35 km/h south wind, treeline temperatures -1 °C with freezing levels up to 1500 m.
Monday
Cloudy, 5 to 15 cm accumulation with possibility of rain in many areas, 25 to 45 km/h south southwest wind gusting to 75, treeline temperatures 1 °C and freezing levels getting up to 2000 m.
Tuesday
Cloudy, up to 15 cm accumulation, 25 km/h south wind, treeline temperatures -8 to -1 °C and freezing levels up to 1500 m.
Wednesday
Cloudy, 2 to 8 cm, 15 to 25 km/h southwest wind, treeline temperatures -8 to -3 °C and freezing levels up to 1200 m.
More details can be found in the Mountain Weather Forecast.
