Avalanche Forecast
Issued: Jan 8th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
cgarritty,
Avalanche Canada
Analyze slopes for patterns of wind effect to navigate around wind slab problems at higher elevations. Observations from the region are limited but we can expect our persistent slab problem became a bit more serious with the recent snowfall.
Summary
Confidence
Weather Forecast
Wednesday night: Cloudy with isolated flurries. Light to moderate northwest winds.
Thursday: Cloudy with scattered flurries bringing a trace to 5 cm of new snow, easing over the day and beginning again overnight. Light to moderate west 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 southeast winds. Alpine high temperatures around -12.
Saturday: Mainly cloudy with isolated flurries and a trace of new snow. Light west winds. Alpine high temperatures around -16
Avalanche Summary
Reports from the region are limited, however 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.
A report from Tuesday includes an observation of a large, audible natural avalanche in the Howson range. Details on the event are limited, but the natural trigger suggests touchy conditions still exist in parts of the region.
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. Loading from recent snowfall has increased this potential.
Terrain and Travel
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Avoid freshly wind loaded terrain features.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
Problems
Wind Slabs
40-60 cm of recent storm snow and strong, variable winds have promoted wind slab formation in the lee of exposed terrain features. This problem should be anticipated on all aspects. It may still be possible to trigger a storm slab on steeper slopes in sheltered areas at lower elevations
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 9th, 2020 5:00PM
