Diligence may be required to maintain conservative decisions in the face of fair weather and decent riding conditions over the weekend.
Weather Forecast
Mostly cloudy with a chance of light flurries Friday evening and Saturday, but generally dry for Sunday. Freezing levels remain in valley bottoms for the forecast period, with above freezing alpine temperatures expected for Friday. Winds should remain generally light and variable.
Avalanche Summary
Reports from Wednesday include several explosive triggered persistent slab avalanches up to Size 3, some running on facets near the ground. Numerous natural 40-60 cm thick slab avalanches up to Size 2 were also observed south through west facing treeline and alpine slopes in response to sun-exposure.
Snowpack Summary
There is a great deal of variability across the region. The West and South have received up to 60 cm of storm snow earlier in the week, quickly followed by high freezing levels and warm air up into the alpine. The North and East of the region have had 20-30 cm of cold dry new snow with light Northeast winds. This new slab may be bonding poorly to a patchy layer of surface hoar that was buried near the end of December. Deeper in the snowpack there is a persistent weak layer of surface hoar and crust that is now down about 60 cm.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.