New snow and strong winds are building fresh and reactive storm slabs while rain soaks the snowpack at low elevations. Natural and rider triggered avalanches are likely on Friday.
20 to 40 cm of storm snow has formed fresh and reactive storm slabs. Sensitivity could be greater in areas where storm and wind slab has formed over a crust, facets, or surface hoar.
Loose-dry avalanches and sloughing will likely be seen on steeper terrain features in the alpine/ treeline where the new snow falls on a crust.
Fluctuating freezing levels may bring rain rather than snow at lower elevations. Wet loose avalanches may be widespread, especially from steeper slopes with an underlying crust.
Thursday night: 5-15 cm in most areas, heavier amounts in coastal areas, falling as rain at low elevations. Extreme SW wind. Freezing level 500 m.
Friday: 5-15 cm in most areas, falling as rain at low elevations. Strong SW wind. Freezing level 1000 m. Alpine temperature around -1 C.
Saturday: A mix of sun and cloud. Moderate to strong W wind. Freezing level 800 m. Alpine temperature around -4 C.
Sunday: Snowfall 10-20 cm. Strong SW wind. Freezing level 1000 m. Alpine temperature -2 C.
On Wednesday, natural activity was limited to a few size 1 storm slabs. Storm slabs were reactive to ski cuts to size 1 and explosives averaging size 2.
10-30 cm of new snow is forecast to accumulate by the end of Friday. This now brings 50-100 cm of recent snow above a variety of surfaces that formed during the end of January. This interface is made up of a crust, facets, and surface hoar. The crust can be found at or below treeline as well as on south-facing terrain in the alpine. In isolated sheltered terrain at treeline surface hoar has formed along with facets above this crust. Where a crust did not form facets will likely be found.
The January 19th surface hoar layer can still be found down 40 to 60 at treeline and above in sheltered terrain. Recent reports indicate that it is becoming less of a concern.
