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Avalanche Forecast

Archived

Jan 13th, 2020–Jan 14th, 2020

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

Regions

South Coast Inland.

Reverse loading has likely formed wind fueled storm slabs in strange places at and above treeline, but cold temperatures should allow them to settle out rather quickly. The ticket Tuesday is seek out wind sheltered terrain where the riding should be great. 

Confidence

Low - Uncertainty is due to how quickly the snowpack will recover and gain strength. Uncertainty is due to extremely variable snowpack conditions reported through the region.

Weather Forecast

After a stormy period it looks like the intensity of the weather will briefly back off until Tuesday night before a series of storms line up for the rest of the week and into the weekend. The storms that are lining up are not particularly juicy, but the snowfall should be pretty consistent.

MONDAY NIGHT: Freezing level at valley bottom, light northwest wind at most elevations, moderate northwest wind at ridgetop, no significant precipitation expected.

TUESDAY: Scattered cloud cover, freezing level at valley bottom, light northwest wind at most elevations, moderate west wind at ridgetop, 1 to 3 cm of snow possible during the day, another 1 to 3 cm possible Tuesday night.

WEDNESDAY: Broken cloud cover at dawn with some clearing in the afternoon, freezing level at valley bottom, moderate southeast wind, trace of snow possible during the day, 1 to 5 cm of snow Wednesday night.

THURSDAY: Broken cloud cover, freezing level at valley bottom, light south/southwest wind at most elevations, strong south/southwest wind at ridgetop, trace of snow possible.

Avalanche Summary

No new avalanche activity to report from Sunday.

On Saturday, the snowpack was reactive to explosive triggers. Some avalanches stepped down to a feathery surface hoar layer buried 50-60 cm deep.

On Thursday explosive control work produced a size 2 avalanche off the Duffey Lake road that released on the mid November facet/crust layer.

Snowpack Summary

On Sunday funky wind out of the N/NE associated with an Arctic Front likely formed fresh wind slabs in locations we aren't used to seeing them. The subsequent cold temperatures should be helping the upper snowpack to settle out quite rapidly.

Previous to Sunday's wind event the riding quality has been phenomenal throughout the region, but there are still some areas for concern deeper in the snowpack:

  • A deep persistent weak layer is at the bottom of the snowpack in the northern half of the region (e.g., Duffey, Hurley). It's made up of sugary faceted grains and a hard melt-freeze crust. This is an atypical setup for this part of the province, it's not going away anytime soon and we should all probably remain a bit wary of big alpine lines, at least for now.
  • There are currently no concerns about deep weaknesses in the snowpack near Coquihalla summit. 
  • Most of the region has an unusually thin snowpack in the alpine.
  • Almost no snow is found below about 1500 m.

Terrain and Travel

  • Be aware of highly variable recent wind loading patterns.
  • Seek out sheltered terrain where new snow hasn't been wind-affected.
  • Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.