Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Jan 16th, 2021–Jan 17th, 2021

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

Northwest Coastal.

The stormy weather continues to hit the coast. Avalanche danger will remain elevated, give the snowpack time to settle and bond.

Confidence

Low - Uncertainty is due to the track & intensity of the incoming weather system.

Weather Forecast

SATURDAY NIGHT - Snow, 10-20 cm and continuing into Sunday / southwest wind, 40-60 km/h / alpine high temperature near -4 / freezing level 1000 m in the south, near valley bottom in the north 

SUNDAY - Flurries, 5-10 cm / southwest wind, 30-60 km/h / alpine high temperature near -2 / freezing level 1000 m in the south, near valley bottom in the north

MONDAY - Mainly cloudy / increasing southwest wind, 30-60 km/h / alpine high temperature near -2 / freezing level rising to 1400 m in the south, near valley bottom in the north

TUESDAY - Snow, 20-30 cm / southwest wind, 50-90 km/h / alpine high temperature near -2 / freezing level dropping to valley bottom

Avalanche Summary

Continued stormy weather will mean that storm slabs are anticipated to be widespread and natural avalanches are expected. Wet loose avalanches may still be possible at lower elevations.

A natural avalanche cycle occurred Thursday into Friday, large (size 2-3) storm slab avalanches were reported along highway corridors. The largest (size 3) avalanches were observed in wind-loaded start zones in the alpine and treeline, but also included below tree line avalanches to size 2 failing on unsupported features. Wet-loose avalanches to size 1.5 were reported from steep rocky slabs below tree line.

There were a few natural avalanches up to size 3 reported in the north of the region on Wednesday. There was also one remotely triggered size 3 persistent slab avalanche reported in the north of the region.

There was a natural avalanche cycle reported on Tuesday, as well as numerous explosives triggered avalanches up to size 2.5 and a few human triggered size 1 avalanches.

On Monday, there were reports of widespread natural and explosives triggered avalanches up to size 3. The largest avalanches were reported in the north of the region where there has been more recent snow. The avalanches being reported closer to Terrace were generally in the size 1-2 range.

Snowpack Summary

Another 10-20 cm will accumulate through Sunday. Storm snow totals range around 80-140 cm, with 30-50 cm recent loose snow over older, more settled storm snow. Southerly winds have formed deep deposits in lee terrain and mild temperatures have encouraged settlement. Below 800 m rain on snow produced a moist and upside down snowpack, a crust will form as temperatures cool. 

In the Shames area, a weak layer of surface hoar has been reported in sheltered areas down around 120-180 cm. 

A bit further north in the Nass/Sterling/Beaupre areas, there is potentially still concern about an older weak layer overlying a crust that is now roughly 180-200 cm deep. 

In the far north of the region, there is concern about weak snow at the bottom of the snowpack.

Terrain and Travel

  • Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
  • Avoid avalanche terrain during periods of heavy rain.
  • Storm slabs in motion may step down to deeper layers resulting in large 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.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.