Regions
Northwest Inland.
Confidence
Poor - Due to limited field observations for the entire period
Weather Forecast
Cool arctic air remains embedded in Northern Regions bringing light snow amounts and moderate SE winds. Strong outflow winds will persist through Friday, easing off Saturday. The arctic air will keep cold surface temperatures through the weekend with no inversions. Friday: FLVL’s surface, snow amounts near 5 cm, ridgetop winds SE 30 km/hr with strong valley outflows, alpine temps -12.Saturday: FLVL’s surface, snow amounts near 5 cm, ridgetop winds SE 20km/hr, alpine temps -10.Sunday: FLVL’s surface, ridgetop winds SE 20 km/hr, alpine temps -11.
Avalanche Summary
No new natural avalanches have been reported. Fresh wind slabs have been observed in exposed areas, but slope testing produced very few results. Storm slab and fresh wind slab instabilities may be easily triggered by a rider.
Snowpack Summary
New storm slabs, and wind slabs continue to form over the next few days, and instabilities are likely to exist. The new snow will add to the variable snow depths, and weaknesses that rest below. At treeline depths in the southern part of the region range between 70 – 125 cm, but highly variable in the alpine with deep wind drifts and scoured slopes in exposed areas. A couple of notable weaknesses have been observed in the snowpack: first, a storm snow weakness (may also include small surface hoar) down 40-50cm. Second, a facet/crust combo that formed in early November is now down 40-75cm. This layer has produced moderate "drops" results in recent snowpack tests. Because this weakness is so close to the ground in most areas, associated avalanche activity will likely be limited to slopes with smooth ground cover (e.g. scree slopes, rock slabs, grassy areas, etc.)It will be important to keep tabs on this layer through the next storm cycle, and monitor its reaction to the additional load. Check out the recent forum posts here.
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.