Regions
Kootenay Boundary.
A big change is on the way beginning Thursday. Keep your eyes peeled for small sensitive wind slabs and fast running sluff, especially if you're hunting some of the bigger trophy lines Wednesday.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Thursday
Weather Forecast
Freezing levels should begin to climb Wednesday as warm air begins to move in from the coast. I expect the freezing level to top out at 1300m Wednesday as the warmth begins to make it's presence, but it should return to Valley Bottom overnight. Looks like light variable winds at treeline with moderate west winds at ridgetop, but no significant precipitation on Wednesday. The freezing level should only climb to 800m Thursday as it snows/rains. We're expecting between 4 & 13mm of precipitation during the day with moderate SW winds at treeline and strong SW winds at ridgetop. The current timing shows the warm air coming in with a vengeance Thursday night which should push the freezing level to 2000m overnight along with a healthy amount of precipitation (7 - 17mm) which will likely fall as rain below 2000m with the potential for 10 - 25cm of snow above treeline. By Friday winds should be screaming out of the SW with the bulk of the expected 8 -25mm falling as rain below around 2200m. Saturday looks super warm, wet and windy as well.
Avalanche Summary
New avalanche activity has been limited to minor sluffing in steep terrain.
Snowpack Summary
5 - 20 cm of new snow which was initially accompanied by moderate SW winds now sits on a widespread and mostly supportive melt-freeze crust 1 - 15cm thick that is topped by 6 - 15mm surface hoar. This combo has been reported on all aspects and elevations. The mid-January weak layer of buried surface hoar is down 25-65 cm and continues to give planar results in snow profile tests. The mid-December crust/facet/surface hoar combo found down 50 - 100cm is largely unreactive.
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.