Regions
Northwest Inland.
Storm conditions will keep the hazard elevated in the south of the region for the next couple days. Stick to simple, mellow terrain and give the storm snow a few days to stabilize.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
The next storm pulse hits the NW on Monday night. Southern parts of the inland region may see 10-20mm of precipitation whereas the north is around 5-10mm. Alpine wind is expected to be moderate-to-strong from the SW and treeline temperatures are expected to be around -12C. There will be a bit of a break during the day on Tuesday before the next storm pulse hits on Tuesday night. Another 5-10mm is expected. On Wednesday, a temperature inversion is expected to form and a layer of above-zero air may sit in the alpine. Light precipitation is possible and winds are expected to be moderate from the SW. Thursday looks to be the warmest with freezing levels reaching up to 2500m. The inversion should keep the valleys cooler. Dry conditions are expected on Thursday with light winds.
Avalanche Summary
Reports of unobserved natural activity occurring on Sunday in the south of the region. Also reported was a size 1 skier triggered storm slab avalanche. This released down 15-30cm on a convex roll at treeline. Storm slabs are expected to continue to build in the south of the region. Wind slab formation is expected across the region.
Snowpack Summary
Recent winds have been highly variable with strong W-NW winds followed immediately by strong SE-NE winds. Hard and soft wind slabs should be expected on a variety of slopes in open terrain. rain was reported to almost 2000 m on New Years Day in the southern part of the region. Since then there's been around 20-50 cm of new snow. The new snow may be resting on older wind slabs or surface hoar in northern areas. Down 40-70 cm you may find another surface hoar layer, although it appears to be spotty in distribution. Near the bottom of the snowpack is a crust facet combo that was buried in mid-November. This layer is currently dormant and produces variable results in snowpack tests. I suspect it will remain sensitive to new inputs in the form of new snow and wind for the foreseeable future.
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.