Avalanche Forecast
Issued: Jan 7th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
zryan,
Avalanche Canada
Avalanche danger will rise through the day as new snow and wind form fresh, reactive slabs. If you see more than 25 cm of new snow, treat avalanche danger as HIGH.
Summary
Confidence
Weather Forecast
Friday Overnight: Snowfall, 5-15 cm of accumulation. Strong southwest winds. Alpine temperatures around -15 C.
Saturday: Continued snowfall, 10-20 cm of accumulation. Strong southwest winds. Alpine temperatures rising to -10 C. Snowing overnight, 10-30 cm accumulation.
Sunday: Snowfall easing, 5-10 cm accumulation. Strong southerly winds. Alpine temperatures rising to -5 C.
Monday: Snowfall increasing again overnight, 10-25 cm of accumulation. Strong southwest winds. Alpine temperatures around -5 C.
Avalanche Summary
Highway avalanche control near Shames produced several size 1.5 to 2 wind slab avalanches with explosive control on Thursday.
On Thursday, operators north of Terrace reported a size 1 skier triggered persistent slab avalanche on an east aspect in an open area at treeline. This avalanche failed on a layer of surface hoar buried at the end of December. There has been no other reports of reactivity on this layer and it seems like a fairly isolated event.
Snowpack Summary
Overnight, 5-15 cm of new snow accompanied by southwest winds will have created wind slabs in open areas in the alpine and treeline. Continued snow and wind through out the day will build fresh, reactive wind slab in lee areas.
This new snow overlies a previously wind affected surface, comprised of older hard wind slabs, sastrugi, and areas scoured to the ground or old crusts. Near surface faceting, and in isolated areas surface hoar, above the old surface may increase the reactivity of newly formed wind slabs.
The early December rain crust is up to 10 cm thick, down 80-150 cm in the snowpack, and exists to an average of 1400 m in elevation. Up to 2 mm facets have been reported above this crust, and it is producing hard but sudden planar results in snowpack tests in areas north of Terrace. While this layer has generally gone dormant in the region, it still has the possibility of waking up with new snow load or warming, and wind slab avalanches may still have the potential to step down to this deeper layer in isolated areas.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be aware of highly variable recent wind loading patterns.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Keep your guard up at lower elevations. Wind slab formation has been extensive.
Problems
Wind Slabs
Expect avalanche danger to increase throughout the day as snowfall and southwest winds build fresh, reactive wind slabs in lee areas in the alpine and treeline.
Older, hard windslabs exists below the new snow from northeasterly outflow winds earlier in the week. These slabs exists at all elevations and may be quite stubborn to trigger, but would be larger and more consequential.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 8th, 2022 4:00PM
