Major warming and sun are expected to destabilize the snowpack over the next few days. The recent storm snow is expected to be reactive on Friday, cornices will start to weaken, and deep weak layers may begin to wake up. Wet loose activity is expected on steep sun exposed slopes.
The recent storm snow may become reactive as it settles rapidly with warming on Friday. It will likely be touchy in high elevation wind loaded terrain. Cornices will also begin to weaken with warming Friday.
Wet loose avalanches will become possible at all elevations with warming this weekend. Extra caution will be required around steep south facing slopes when the sun is strong.
An old persistent weak layer buried deeply in the snowpack has been dormant recently but will get tested this weekend with the sustained warming event. Cornice falls or smaller avalanches have the highest potential to step down to a deeply buried weak layer.
A warm ridge of high pressure establishes itself over the region on Friday and is expected to bring sustained freezing levels around 3000 m with an inversion for the weekend.
Thursday Night: Partly cloudy, light to moderate NW wind, freezing levels 1200-1400 m.
Friday: A mix of sun and cloud, light to moderate NW wind, freezing levels climbing to around 3000 m with an inversion.
Saturday: Mainly sunny, light NW wind, freezing levels around 3200 m with an inversion.
Sunday: A mix of sun and cloud, moderate SW wind, freezing levels around 3000 m dropping to around 2000 m by the end of the day.
On Wednesday, a size 1.5 glide slab was observed at 1400 m in the Coquihalla area as well as several size 1 loose wet avalanches sliding on the crust. On Tuesday, a ski cut triggered a size 1 wind slab on a NE aspect at 1950 m in the north of the region failing down 30 cm on a crust. A size 1.5 wind slab was also remotely triggered from a ridge on a NW aspect at 1950 m.
At higher elevations, the recent storm snow has buried the widespread January 16 melt-freeze crust which extends into alpine elevations. There have also been reports of a layer of small surface hoar above this crust in the north of the region. The most recent storm snow is expected to have formed reactive wind slabs in exposed high elevation terrain. At lower elevations, the upper snowpack is moist or wet from the recent rain event.
The early December crust/facet layer is now typically down 100-150 cm but may be as shallow as 60 cm and as deep as 200 cm with lots of variability through the region. The layer is most prominent between 1700 and 2100 m. The crust appears to be breaking down in the south of the region but remains a concern in the north. The layer has been dormant recently but is a concern for the period of major warming and sun forecast for the weekend. The most likely place to trigger it would be in thin, rocky snowpack areas where it is shallowest.
