Avalanche Forecast
Issued: Jan 13th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
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Avalanche Canada
Dial back your exposure to avalanche terrain when temperatures increase. Large avalanches are possible as buried weak layers adjust to the warming.
Summary
Confidence
Weather Forecast
THURSDAY NIGHT: Partly cloudy, no precipitation, moderate wind from the northwest, treeline temperatures cool to -4 C with freezing level dropping somewhere below 1500 m.
FRIDAY: Mix of sun and cloud, no precipitation, light wind from the northwest, treeline and alpine temperatures around -2 C with freezing level around 1200 m.
SATURDAY: Mostly cloudy with isolated flurries, trace amounts of new snow, moderate wind from the southwest, treeline temperatures around -2 C with freezing level around 1200 m.
SUNDAY: Mostly sunny skies, no precipitation, moderate wind from the west, treeline temperatures around -4 C.
Avalanche Summary
Wednesday's storm resulted in some small (mostly size 1) slab avalanches in the top 15 cm of new snow. Explosive control in the Invermere area produced a few size 2 avalanches that failed on the early December persistent weak layer. These occurred on relatively shallow northeast-facing slopes at 2000 m, where the layer was buried 60-80 cm deep.
We have seen sporadic avalanche activity on this persistent weak layer since Jan 4. These have included some large human triggered avalanches, such as this size 3.5 avalanche just outside the region at Pedley Pass on Jan 4 and this avalanche near Golden on Jan 9, as well as large natural avalanches like this one reported in the South Purcells on Jan 9. These avalanches suggest the persistent slab problem is an ongoing concern in the Purcells.
Snowpack Summary
15 cm of recent snow is rapidly settling, with surfaces at lower elevations likely going through a daily melt-freeze cycle. Dry snow can likely be found in alpine terrain, although it will likely be wind-affected. This most recent snow has buried some small surface hoar and melt-freeze crusts. The snow should bond to these layers relatively quickly, but could remain unstable in isolated pockets. The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 90-160 cm. Activity on this layer has been sporadic, but has generally been triggered on steep, rocky slopes, with a shallow or thin-to-thick snowpack.
Terrain and Travel
- The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Use ridges or ribs to avoid areas of wind loaded snow.
Problems
Persistent Slabs
A persistent slab problem formed by a crust down 90-160 cm has created a low likelihood, high consequence scenario that is difficult to forecast. It is uncertain how the forecast warm temperatures will affect the snowpack and if we will see more activity on this layer during the warm period. Avoid likely trigger spots such as steep, rocky slopes with a shallow or thin-to-thick snowpack.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Wind slab avalanches are possible at upper elevations where wind has blown dry snow into unstable slabs. While these slabs may be thin, they could be poorly bonded to the underlying snow, so be extra cautious in lee terrain and convex rolls.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 14th, 2022 4:00PM
