Avalanche Forecast
Issued: Nov 22nd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
Aaron Beardmore,
Potential still exists to trigger wind slabs on steep alpine features like convex roll overs and couloirs. Conditions appear to be improving but step out with forethought and careful consideration.
Summary
Weather Forecast
Seasonal temperatures will persist in the region for the next 3 days. The valley will be near zero, with the ridge line being about -10. Upper level winds are expected to drop significantly tomorrow, with calm conditions up high. This will be disrupted by a once again strong wind pattern from the SW on Tues. Snow arriving again late Tuesday.
Snowpack Summary
Wind slabs present at treeline and above from W-SW winds. At treeline 20-50 cm of storm snow sits over a layer of preserved stellars. The Nov. 5 facet/crust combo is down 50-80 cm and producing variable test results from easy to hard. The Nov crust extends up to 2500 m on N aspects and higher on solar aspects. Snow depths at treeline are 50-130 cm.
Avalanche Summary
Today's field team, was near Bow Summit today. No avalanches were observed or reported in that area. Sunshine ski patrol, however, did report a size 2.5 avalanche that ran near the ground, likely yesterday, but was observed today. Control work at Sunshine produced avalanches up to size 1.5, in the form of wind slabs.
Confidence
Due to the number and quality of field observations on Sunday
Problems
Wind Slabs
Little wind slab activity was observed today, even with evidence of the public skiing steeper alpine features on Sunday. Wind slabs can be felt underfoot in many locations, however the sensitivity has decreased. Don't let your guard down yet.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The Nov.5 crust/ facet layer exists up to 2500m on shady aspects, and higher on solar aspects. Where there is a dense slab overlying this layer, it remains a concern, and likely will be for the foreseeable future.
- Be aware of thin areas that may propogate to deeper instabilites.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 23rd, 2020 4:00PM
