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Avalanche Forecast

Dec 23rd, 2017–Dec 24th, 2017
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
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: Sea To Sky.

Strong northerly, outflow winds have scoured windward slopes and created hard wind slabs on lee slopes at upper elevations. Watch for areas of "pillowy" or hollow, drum-like sounding snow.

Confidence

High - The weather pattern is stable

Weather Forecast

SUNDAY: Cloudy, flurries. Accumulation 2-5 cm. Ridge wind light from the southeast. Temperature -7. Freezing level surface. Strong outflow winds near coastal valleys.MONDAY: Mostly cloudy, flurries. Accumulation trace. Ridge wind light from the northwest. Temperature -6. Freezing level surface.TUESDAY: Mostly sunny. Ridge wind light from the southwest. Temperature -8. Freezing level surface.

Avalanche Summary

There have been no reports of avalanche activity since Thursday when there was a report of a small (size 1) skier accidental wind slab release on a north aspect in the alpine. On Wednesday, several small, skier-triggered avalanches were reported as well as explosives triggered slab avalanches up to Size 3 on wind-loaded slopes in the alpine and at treeline. See here and here for recent Mountain Information Network (MIN) reports.And earlier in the week, numerous natural, skier controlled and skier remote storm slab avalanches to Size 2 were reported on various aspects and all elevations running both within the storm snow as well as on the Dec 15th melt-freeze crust. See here for details.

Snowpack Summary

The recent storm snow has been redistributed by strong northerly winds scouring windward, north to west aspects and building wind slabs on leeward, south to east aspects in the alpine and exposed treeline areas. This has created a highly variable upper snowpack with areas of both soft and hard snow as well as areas of exposed crust, depending on aspect and elevation. An average of 30-50cm of storm snow now sits on a melt-freeze crust (December 15th layer) that formed on all aspects and elevations. On high north aspects this crust is thin with dry, sugary snow crystals (facets) below. Below the December 15th layer, the late November crust is now buried 70-100 cm with a thin layer of facets above. Beneath this crust the lower snowpack is well settled.

Avalanche Problems

Wind Slabs

Wind affect at upper elevations is highly variable with both soft and hard wind slab on leeward slopes slopes and exposed treeline areas. These may still be reactive to light loads such as a skier or rider.
Watch for whumpfing, hollow sounds, and shooting cracks.Be cautious as you transition into wind affected terrain.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2