Avalanche danger will increase on Thursday with the incoming snow, wind, and mild temperatures. Monitor accumulations of new snow in your local riding area and reduce your exposure to avalanche terrain accordingly.
A buried surface hoar layer has been a problem around Pine Pass, and could exist in other parts of the region too. It is typically 50-80 cm below the surface, but deeper on wind-loaded slopes. Treeline slopes are most likely to harbour this problem, as seen by photos of avalanches reported on the Mountain Information Network here and here.
New snow and wind will form dangerous storm and wind slab avalanches on Thursday. Natural wind slab avalanches will be likely in alpine terrain and dangerous storm slabs could form at all aspects and elevations in parts of the region that receive more than 20 cm of new snow. Natural avalanche activity should reduce on Friday and Saturday, but storm and wind slabs will remain reactive to human triggers.
A series of frontal systems crossing the region Wednesday to Friday will deliver moderate to heavy snowfall to the region with strong wind and mild daytime temperatures.
WEDNESDAY NIGHT: 5-15 cm of snow along the western side of the continental divide and 2-5 cm along the eastern side, strong southwest wind, freezing level climbing to 1000 m with alpine temperatures around -5 C.
THURSDAY: Heavy snowfall in McBride and Kakwa (15-20 cm), moderate snowfall at Pine Pass and Torpy (10 cm), and light snowfall around Tumbler (5 cm), strong southwest wind across the region, freezing level climbing to 1200-1400 m with alpine temperatures reaching -2 C.
FRIDAY: Snowfall continues Thursday night and eases midday Friday with another 5-10 cm of snow, cloudy with sunny breaks in the afternoon, moderate southwest wind, freezing level rises to 1200-1400 m in the afternoon, alpine temperatures reaching -2 C.
SATURDAY: Current forecasts suggest an upslope storm could deliver up to 10 cm of snow to the eastern slopes of the region and less on the western slopes (stay tuned for more up-to-date forecasts), moderate northeast wind, freezing level drops back to valley bottom with alpine high temperatures around -7 C.
No notable avalanches have been reported since the weekend when two large (size 2.5) persistent slab avalanches were reported on northeast slopes at Bijoux (see the Mountain Information Network report for photos). One appeared to be triggered by a snowmobile, while the other was triggered naturally by a cornice fall. Similar persistent slab avalanches were reported last week on buried surface hoar layers up to 100 cm below the surface.
Variable amounts of new snow over the coming days will develop new storm and wind slab avalanche problems that will be more dangerous in areas that receive heavier accumulations of new snow. In areas where buried surface hoar exists, triggering large persistent slab avalanches remains a concern. Cornices are also becoming an increasing concern with mild temperatures.
Between Monday and Friday anywhere from 15 to 50 cm of new snow is possible in the region. Areas with heavier accumulations will likely have widespread storm slabs, while areas with lighter accumulations will have more localized wind slabs. The new snow is accumulating above hard wind affected snow in open terrain and crusty snow at low elevations and on south and west facing slopes. Some of these interfaces could form sliding surfaces for the new snow.
Cornices will likely grow larger and could become fragile with the mild temperatures in the forecast.
The lower snowpack is strong in many parts of the region with two main exceptions:
