A trending temperature inversion may see a change in storm slab development. Watch for signs of instability such as whumphing, cracking and new natural avalanche activity.
Weather Forecast
A temperature inversion will see alpine highs up to -5C with a mix of sun and cloud today. Warming will continue into Tuesday with alpine temperatures reaching zero degrees. Wednesday freezing level should reach 1700m with alpine temps reaching zero degrees.
Snowpack Summary
25cm of low density storm snow now buries the Dec 27 surface hoar/ facet layer. The Dec 15 surface hoar/sun crust layer, which is widespread at treeline, is buried down 60cms. An inversion warming trend could mark a change in storm slab formation. Expect to find pockets of wind slab in the alpine and open areas at tree line.
Avalanche Summary
A natural avalanche cycle occurred on Dec 30 with numerous loose dry and storm slab avalanches up to sz 3.0, from steep, confined terrain. Dec 31, 4 slides to size 2.0 were observed in the hwy corridor. Be aware of naturals from above especially while traveling in confined valley bottoms as avalanches have the potential to reach into run-out zones.
Confidence
Due to the number of field observations
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.