Another 25 cm of new snow is forecast to blanket the region overnight. Natural avalanche activity is expected at all elevations on Thursday. Storm slab reactivity may persist for longer than typical, due to the weak surface they are sitting on. Human triggering remains likely.
In areas where the recent storm snow lacks cohesion, dry loose avalanches will be likely from steep terrain features. Avoid areas with terrain traps like gullies and cliffs.
More snow and strong winds will build touchy storm slabs on Thursday. The recent storm slab is averaging 30-60 deep and up to 100 cm deep in wind-loaded areas may have bonded poorly to the underlying surface.
Storm slab reactivity is expected to persist for longer than is typical, particularly in areas where slabs are sitting on a weak layer of facets and/or a crust.
On Tuesday, a few natural storm slab avalanches were reported at treeline and below treeline elevations up to size 2. Most of the slabs were 30 cm deep with one significant one being 60 cm deep. Skier-controlled dry loose avalanches were easily triggered up to size 1 from steep terrain features on all aspects.
Last weekend, a widespread natural cycle occurred throughout the region. Reports came in of very touchy human-triggered storm slabs (size 1-2) averaging 30-60 cm deep and up to 100 cm deep in wind-loaded areas.
Storm slab reactivity is expected to persist for longer than is typical due to the weak surface they are sitting on.
Check out last Friday's North Shore Snowpack Update for a picture of the unusual snowpack setup leading into last weekend's storm.
Another storm tonight could bring 20+ cm of new snow to all elevations above the 50-70 cm that has accumulated since last weekend. The recent cold temperatures have kept the snow mostly dry and unconsolidated, however, storm slabs will likely be more reactive with the additional load from wind, rising temperatures, and more snow. The recent snow will likely have a poor bond to the underlying old snow surfaces. This interface consists of weak faceted snow, old hard wind slabs, and a crust between 1100 and 1600 m.
The mid and lower snowpack is well-settled, strong, and consolidated.
Snowpack depths are reaching 250 cm at treeline.
Wednesday Night
New snow 20 to 30 cm. Treeline temperatures -5°C. Ridge wind southwest 30 to 60 km/h. Freezing level 300 m.
Thursday
Cloudy with snow up to 10 cm. Possible sunny breaks and treeline temperatures -4 °C. Southwest wind 25 to 60 km/h. Freezing level 600 m.
Friday
Snow amounts 10-15 cm. Ridgetop wind 20 to 55 km/h from the southwest. Treeline temperatures -3 °C. Freezing level 500 m.
Saturday
Cloudy with isolated flurries. Treeline temperatures near 1 °C. Ridge wind southwest 15 km/h gusting to 40 km/h. Freezing level 1000 m.
More details can be found in the Mountain Weather Forecast.
