Avalanche Forecast

Fair - Forecast snowfall amounts are uncertain on Sunday

Expect freezing levels to drop back to valley bottoms by Friday morning as a weak ridge of high pressure moves in from the coast. High clouds may become broken skies by afternoon, providing a bit of sunshine to some of the more western areas. Friday night is forecast to be cooler again, with mountain top temperatures dipping to at least -15.0 C. The ridge should continue to affect the interior mountains on Saturday resulting in mostly clear skies and ridgetop highs around -8.0 C. The next Pacific system is on track to bring warm windy and wet weather for Sunday. Preliminary models show freezing levels rising to about 1400 metres combined with about 20 cm of new snow.

There have been a few reports of natural cornice falls landing on slopes and entraining enough snow to get to size 2.5. The interesting thing here is that these cornice falls did not propagate wide releases on buried persistent weak layers. These slopes may have already released from natural or human triggers. I suspect that there was a natural avalanche cycle Wednesday night or early Thursday morning that has not been reported due to poor visibility and travel conditions.

The height of snow in the region is between 200 cm in the drier areas and close to 300 cm in the wetter areas. There was another 10-20 cm of new snow on Wednesday night. This new snow combined with the previous nights 30 cm brings the recent storm total to about 50 cm. The storm has been very mild, with freezing levels near 1800 metres on Wednesday. The temperatures started to fall early Thursday morning when the rain and snow moved out of the region. The winds have been very strong from the south and southwest. Expect to find windslabs on north and northeast aspects in the alpine and at treeline. There may be a rain crust developing below 1600 metres as the freezing levels drop back to valley bottom. The previous storm snow is now fairly well consolidated and makes for a generally strong mid-pack. A surface hoar layer buried around Christmas is well preserved, now buried around 80 cm below the surface and is producing sudden "pop" results in stability tests. A surface hoar/facet/crust interface from mid-December is also still preserved. This one is buried 100 to 150 cm deep and is still reactive to natural and human triggers. Despite sudden snowpack test results, triggering these weak layers is proving difficult; however bear in mind if anything did release on either of these layers, the consequence of the resulting slide would be large.