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Avalanche Forecast

Archived

Dec 14th, 2020–Dec 15th, 2020

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Sea To Sky.

New snow and strong southwest winds are forming reactive slabs. Avoid freshly wind loaded terrain features. The buried crust offers a slick bed surface for avalanches.

Confidence

Moderate -

Weather Forecast

Monday night: 5-10 cm new snow, wind increasing to strong southwest, freezing level 700 m.

Tuesday: 10-20 cm new snow, strong southwest ridgetop wind, alpine high -5 C, freezing level 1200 m.

Wednesday: 5-15 cm new snow, light to moderate southwest ridgetop wind, alpine high -4 C, freezing level 1200 m.

Thursday: 10-20 cm new snow overnight, wind easing to light northwest, alpine high -5 C, freezing level 1300 m.

Avalanche Summary

On Sunday, small natural and skier controlled size 1 loose dry and wind slab avalanches were reported running on the crust.

Solar triggered loose snow avalanches size 1-2 were reported on steep solar aspects in the alpine on Saturday. A size 1.5 natural cornice fall was also reported in this MIN from the Garabaldi area.

Have you been out and about in the mountains? If so please submit your observations to the Mountain Information Network (MIN). It doesn't have to be technical - photos are especially helpful! Thank you so much for all the great MINs submitted so far! 

Snowpack Summary

15-25 cm of new snow is forecast to fall by the end of the day Tuesday. As it falls, the new snow iis being loaded into lee features in wind exposed areas by strong southwest wind. 

In wind sheltered areas, the new snow may be falling on a layer of small surface hoar crystals. A second layer may also exist in close proximity below.

A crust is now buried by 20-50 cm of snow at elevations above 1000 m. Prior to the new snow, the crust was punchy below 2000 m with a moist snowpack below. The new snow will likely help with bridging, and improve travel conditions.

Snowpack depths change rapidly with elevation, with 0-50 cm below treeline to 170 cm in the alpine.

Terrain and Travel

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Avoid freshly wind loaded terrain features.
  • Keep in mind the crust offers an excellent bed surface for avalanches.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.