Regions
Northwest Inland.
New snow and wind may form reactive storm slabs on Tuesday. Watch for signs of increasing danger such as cracking, whumpfing, or avalanche activity.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
TUESDAY: Scattered flurries with 5-15 cm of new snow, moderate south wind, alpine high temperatures near -10 C, freezing level up to 400 m.WEDNESDAY: Mostly cloudy and light snowfall with accumulations of 1-3 cm, light south wind, alpine high temperatures near -9 C, freezing level up to 500 m.THURSDAY: Light flurries with trace accumulations, light to moderate south wind, alpine high temperatures near -10 C, freezing level up to 400 m.
Avalanche Summary
Avalanche activity on Sunday was limited to a few small loose avalanches on steep sun-exposed slopes.On Saturday, a large persistent slab avalanche was reported in the north of the region, failing on the early-March weak layer. It failed on an easterly aspect around treeline. Portions of the avalanche stepped down to sugary facets near the bottom of the snowpack.Otherwise, there was further evidence of a large natural cycle that occurred on Friday within the recent storm snow, with storm slab and loose dry avalanches. They were small to large (size 1 to 2.5), on all aspects and elevations.
Snowpack Summary
5-15 cm of new snow is expected on Tuesday. The new snow will sit above a sun crust on southerly aspects from the weekend's clear skies.A reactive slab about 50 cm thick has developed after last week's storm. On shaded aspects at high elevations, this slab overlies two layers of weak surface hoar. On all aspects below treeline, the slab sits on a melt-freeze crust. The storm snow may still be loose in sheltered and shady locations.Near the bottom of the snowpack, weak and sugary facets are found in shallow, rocky snowpack areas. Storm slabs have stepped down to these facets recently, producing very large avalanches.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.