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Avalanche Forecast

Dec 1st, 2016–Dec 2nd, 2016
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
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

Regions: Sea To Sky.

Fridays storm is driving the danger ratings. If your local riding area receives more than 30 cm of new snow expect the danger to be HIGH at upper elevations.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

An organized low pressure system continues to intensify over the Pacific Ocean bringing strong winds and significant precipitation by Friday and through the weekend. A ridge of high pressure will set up Sunday with an arctic front forming along the coast. Residual moisture will exist Sunday and Monday so you can expect unsettled conditions through Tuesday before the Arctic front sets in with a typical clear, dry and cooling trend. Friday: Freezing Levels 1200 m, alpine temperatures -2.0, snow amounts 10-25 cm, strong SW winds.Saturday: Freezing levels 1100 m, -6.0, snow amounts 5-10 cm, moderate-strong SW winds.Sunday: Freezing levels dropping to valley bottom, alpine temperatures high of -9.0,  isolated flurries, and moderate West winds.

Avalanche Summary

Reports on Wednesday suggest that recent wind slabs remain reactive to rider triggers in isolated lee terrain. This next system will bring significant wind and snow to the region and natural avalanche activity will be on the rise for Friday and Saturday.

Snowpack Summary

New storm slabs will blanket the region, continuing to bury a recent surface hoar layer. Areas with this layer and where buried wind blasted surfaces exist may be more reactive. Watch for shallow wind affected areas that may not gain strength as quickly as deeper well settled snowpack areas. Snow depths increased rapidly last week bringing treeline snow depths to about 200 cm. The mid- November crust is buried anywhere from 20-200 cm depending on aspect and elevation. So far this crust has been unreactive, however; this new load may be the breaking point especially in shallower snowpack areas.

Avalanche Problems

Storm Slabs

Storm slabs will build and likely be reactive during this next storm. Strong SW winds will load lee slopes and terrain features.
Be alert to conditions that change with elevation.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2

Persistent Slabs

The early November crust is now buried between 30-200 cm deep. The bond between the crust and the storm slab from last week is variable. Avoid convex slopes where the storm slab may be able to propagate wide and deep fractures above the crust.
Use caution on open slopes with convex rolls that may propagate long avalanche fractures.Use caution in areas where the old surface crust was polished by the winds before it was buried.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3