Avalanche Canada ghelgeson, Avalanche Canada

South Coast Inland Avalanche Forecast

Jan 13th, 2020 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Storm Slabs and Persistent Slabs.

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. 

Summary

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

An icon showing Storm Slabs

Likelihood

Possible-Likely

Expected Size

1 - 2

Recent storm snow combined with unusual northerly wind has likely formed wind fueled storm slabs in strange places. These should be easy to avoid, if the snow feels stiff under your skis, track or feet, back off to more wind sheltered terrain.

Aspects:

All aspects.

Elevations:

All elevations.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3

Two layers that cause concern:

  • In many parts of the region, with the exception potentially being near Coquihalla summit, settling storm snow may overly a surface hoar layer found around treeline elevations in sheltered areas. This layer previously produced large avalanches that have propagated far.
  • In the north half of the region, a weak layer is buried near the bottom of the snowpack which continues to produce sporadic very large avalanches.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Jan 14th, 2020 5:00PM