We've added a Persistent Slab problem due to the slow build of a 40cm slab sitting on top of the Feb.16 crust. Few avalanches reported yet, but this problem is worth paying attention to. Hopefully it will be short lived with the colder air arriving.
20-30 cm has fallen over the last 4 days but with light winds, the windslab formation should be limited to immediate leeward areas only. We have minimal observations from alpine areas.
This is an emerging problem with enough accumulated snow forming a slab on top of the Feb. 16 crust. Be very careful on treeline and alpine slopes that face east, south and west. It's easy to dig down 40 cm and look for the layer too.
The weather pattern is changing overnight on Thursday as a ridge of high pressure brings colder, northern air down into the region. Expect flurries to taper off overnight while the temperature drops to -15 overnight in some areas. Friday will see lingering fog and temperatures from -5 to -10 and Saturday looks like a clear day. Winds light north.
Thursday's moist surface snow will have frozen into a crust up to 2000m on solar aspects. Above 2000m, 40 cm of storm snow has solidified into a slab overlying a suncrust buried on February 16. This combination should now be watched closely, as it produces whumphs and tests indicate propagation (ECTP 21). North aspects don't hold this crust.
No new avalanches observed or reported today, but whumphs (unstable snow) observed on Hawk Ridge in Kootenay Park on Thursday. On Wednesday in Kananaskis Country, a size 2.5 skier remote slab 40 cm deep was triggered on a SE aspect at 2500 m (ran on the Feb. 16 crust).
