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Archived

Avalanche Forecast

Nov 26th, 2019–Nov 27th, 2019
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Northwest Coastal.

Strong wind will maintain dangerous conditions in alpine terrain on Wednesday. Stick to sheltered terrain and be aware that the recent snow may need more time to stabilize.

Confidence

Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack.

Weather Forecast

TUESDAY NIGHT: Clearing skies, 50-70 km/h outflow winds from the northeast, alpine temperatures drop to -12 C.

WEDNESDAY: Sunny, 50 km/h outflow winds from the northeast, alpine temperatures around -10 C.

THURSDAY: Sunny, light wind from the northeast, alpine temperatures around -8 C.

FRIDAY: Sunny, light wind from the northeast, alpine temperatures around -5 C.

Avalanche Summary

While the storms over the weekend likely caused a widespread cycle of natural avalanches, there are few observations at this time of year. Reports from northern parts of the region confirm there were some natural storm slab and wind slab avalanches over the weekend. Looking forward, clearing weather is likely to make travel in the mountains a more inviting prospect, however this is a time to be on high alert in any areas where new snow buried a smooth surface and where winds have formed new slabs. Concern is reduced in areas where the new snow hasn't yet overcome the depth of ground roughness.

Snowpack Summary

Strong wind from the northeast will form new wind slabs on west and south facing slopes at higher elevations. The succession of storms over the weekend delivered much more snow towards the coast than inland (150 mm of precipitation at Shames and only 36 mm at Rosswood). Recent observations from Shames suggest this resulted in about 30 cm of snow at 750 m, 100 cm of snow at 1200 m, and likely over a metre of snow in the high alpine (see this MIN report). Beyond the sheer quantity of new snow (easily tripling the previous snowpack depth), the bond between the new snow and the old crust will remain in question for a few days. Forecast cool temperatures are expected to contribute to a slow bonding process.

Avalanche Problems

Wind Slabs

Watching for blowing snow forming new wind slabs in open terrain. As the wind shifts you may find old hard slabs on all aspects and softer fresh slabs on west and south facing slopes. Picking out where the new snow sits on a smooth surface and where it is anchored in place by rocks may still be tricky.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5