Avalanche Forecast
Issued: Jan 7th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
cgarritty,
Avalanche Canada
Observations from the region are limited but we can expect our persistent slab problem became a bit more serious with the recent snowfall. Choose terrain with this deeper problem in mind, even if you're observing good settlement and bonding of the recent snow.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
Tuesday night: Isolated flurries and a trace of new snow. Light northwest winds, increasing into the morning.Â
Wednesday: Mix of sun and cloud. Light to moderate west or northwest winds. Alpine temperatures around -13.
Thursday: Cloudy with isolated flurries and a trace of new snow, continuing overnight. Light to moderate southwest winds. Alpine temperatures around -10 C.
Friday: Cloudy with continuing flurries and 2-day snow totals of approximately 10 cm by end of day. Light to moderate southeast winds. Alpine high temperatures around -12.
Avalanche Summary
There are no reports of avalanche activity over past two days.
A widespread avalanche cycle is likely to have occurred throughout the southern part of the region on Friday and Saturday, when more than 40 cm of snow fell.
Before the storm, reports of persistent slab avalanches associated with buried surface hoar were trickling in, from Ashman, Houston Telkwas, and the Howsons. They included natural and artificially triggered avalanches ranging in size from 1.5-3, and have occurred on all aspects mainly at treeline but also in the alpine. Loading from recent snowfall has increased the size and consequences of avalanches on these layers.
Snowpack Summary
40-60 cm of recent storm snow has been highly wind affected in the alpine. Expect to find deep wind loaded pockets below ridgetops and the lee sides of exposed features.
A couple of layers of surface hoar are now buried 50-100 cm below the surface in sheltered areas around treeline. Reports of avalanche activity on these layers before the last storm suggest they may be active and loading from recent snowfall has increased this potential.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Problems
Storm Slabs
40-60 cm of recent storm snow and strong southwesterly winds have promoted storm slab formation in lee features with deepest amounts in lee terrain. Watch for solar triggering of recent snow on solar aspects during periods of sun.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A couple layers of surface hoar are now buried 50-100 cm deep. There is uncertainty as to how the buried weak layers have reacted to the new load of storm snow. Human triggering of weak layers at this depth is definitely possible.
Aspects: All aspects.
Elevations: Treeline.
Likelihood
Expected Size
Valid until: Jan 8th, 2020 5:00PM
