Northwest Coastal Avalanche Forecast

Issued: Dec 30th, 2021 4:00PM

Fri Dec 31st Current Conditions
Alpine Moderate Treeline Moderate Below Treeline Low
Sat Jan 1st 2 Day Outlook
Alpine High Treeline High Below Treeline Considerable
Sun Jan 2nd 3 Day Outlook
Alpine High Treeline High Below Treeline Considerable

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

The calm before the storm ! Wind slabs will remain reactive to riders, especially at treeline where they are overlying a weak interface.

Summary

Confidence

High - Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

An arctic ridge of high pressure will briefly build, leading to another clear and cold day heading into Friday. The next round of snow is expected late Friday, with heavy rates of precipitations to invade the northern ranges for the weekend.

THURSDAY NIGHT: Clear / Moderate north winds in the alpine / Low of -18 

FRIDAY: Cloudy / Snow beginning in the evening / Light southwest winds in the alpine / High of -15 / Possible temperature inversion with -8 at 1500 m. 

SATURDAY: Snow 30-50 cm / Strong to extreme southwest winds in the alpine / High of -10

SUNDAY: Snow 20-40 cm / Strong southerly winds in the alpine / High of -10

Avalanche Summary

No human-triggered or natural avalanches were reported in the last 24h. 

If you go out in the mountains, please consider filling out a Mountain Information Network report.

Snowpack Summary

The region received 10-20 cm of new snow Wednesday night, along with strong to extreme northerly winds. Fresh and reactive widespread wind slabs can now be found at treeline and alpine on all southerly slopes. This new snow is likely to poorly bond to the old surfaces, especially in the alpine where the surface is hard wind slabs or scoured surfaces.

Two layers of surface hoar exist within the upper snowpack in protected areas near treeline; one is down 20-40 cm (Dec 21) and the other is down 55 cm (Dec 18) with larger grains up to 12mm. It will likely become a concern in isolated locations in the treeline where a wind slab has formed above it.

Snowpack depths vary greatly across the region, expect to find anywhere from 140-300 cm of snow around treeline.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • Be aware of the potential for large avalanches due to the presence of buried weak layers.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Parts of the region have seen up 20 cm of low-density snow Wednesday night with strong to extreme wind. Expect wind slabs to remain reactive at upper elevations on Friday. Be extra cautious near ridge crests and at treeline and below where wind slabs have formed above a surface hoar layer.

Aspects:

East, South East, South, South West.

Elevations:

Alpine, Treeline.

Valid until: Dec 31st, 2021 4:00PM

Forecast Trend

The latest forecast danger ratings, broken down to elevation. See how an elevation is trending.