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Archived

Avalanche Forecast

Feb 11th, 2020–Feb 12th, 2020
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Northwest Coastal.

New snow and strong wind are coming together to form fresh slabs that may run naturally and are almost certain to be sensitive to human triggering. Watch for increasing avalanche hazard Wednesday afternoon as the next storm begins to impact the region.

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

The northwest coast is set to be the wettest zone in the province for the foreseeable future as a series of storms that began Monday night continue to impact the region, a trend that is expected to be with us through the weekend. It’s worth noting that there is quite a bit of wind in these systems too.

TUESDAY NIGHT: Freezing level at valley bottom, moderate to strong northwest wind, trace of snow possible.

WEDNESDAY: Overcast, freezing level around 500 m,strong to extreme west/southwest wind, 2 to 10 cm of snow possible during the day, 8 to 20 cm possible Wednesday Night.

THURSDAY: Overcast, freezing level around 800 m, moderate southwest wind, 2 to 10 cm of snow possible.

FRIDAY: Overcast, freezing level around 900 m, strong to extreme southwest wind, 5 to 20 cm of snow possible.

Avalanche Summary

Not much new activity to report from Monday other than glide slabs that continue to open up. There is likely some storm slab avalanche activity occurring in the region Tuesday with the 15 to 20 cm of snow that fell Monday night.

Over the weekend wind slabs were widespread to size 2 with an average depth of 30 cm.

We got an observation from the Shames backcountry Saturday of some natural avalanches, more details here. There have been a few observations of natural cornice failures in the last week, some are not having any result when they impact slopes below, others are producing small wind slabs. 

We recently received a report of a very large (size 3.5) persistent slab avalanche that likely ran on February 5th. It ran naturally on a north/northwest facing feature at 1850 m, this avalanche failed on the January facets.

It's also worth noting that glide slabs continue to release randomly, a size 2.5 natural glide slab avalanche was reported from an east facing feature at 700 m near the Basalt Creek Rest Area east of Prince Rupert On Friday February 7th. Glide cracks have reportedly been opening and releasing glide slab avalanches. Avoid slopes with glide cracks, as they are unpredictable.

Snowpack Summary

15 to 20 cm fell across the region Monday night which is being blown into fresh slabs by wind out of the west, southwest and northwest. Wind has been strong from these directions over the last few days which has allowed open terrain to be heavily wind affected, hard slabs are widespread at and above treeline. Cornices are reportedly large on north, northeast and east facing terrain features too.

Wind sheltered features have 10 to 20 cm of faceted snow underneath the 15 to 20 cm that fell Monday night.

A thin layer of facets that formed during the January cold snap is now 100-150 cm below the surface and an early season crust exists at the base of the snowpack. These layers produced a few large naturally triggered avalanches in early February but have more recently been nonreactive.

Terrain and Travel

  • Watch for changing conditions today, storm slabs may become increasingly reactive.
  • Minimize exposure during periods of heavy loading from new snow and wind.
  • Recent new snow may be hiding windslabs that were easily visible before the snow fell.
  • Caution around slopes that are exposed to cornices overhead.

Avalanche Problems

Storm Slabs

15 to 20 cm of new snow fell with strong wind out of the southwest and northwest Monday night. Strong wind is expected to continue Tuesday night into Wednesday. New snow is also expected Wednesday which should allow for the continued formation of fresh sensitive storm slabs. These slabs rest on heavily wind affected terrain which could allow for them to be fast and very sensitive to both human and natural triggering. Storm slabs will be hiding old hard slabs and there is potential for the step down triggering of larger avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1.5 - 2.5