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

Mar 4th, 2021–Mar 5th, 2021

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

Northwest Coastal.

As the storm eases off and temperatures drop, the snowpack is beginning to gain some strength. However, storm slabs are still likely to be encountered at upper elevations and human triggering remains likely, especially in wind loaded areas. Stick to conservative terrain.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

THURSDAY NIGHT - Flurries, 5-10 cm / strong southwest wind / alpine low temperature near -7 / freezing level 1200-1500 m, dropping to near valley bottom overnight

FRIDAY - A mix of sun and cloud with flurries starting in the afternoon, 5-10 cm / strong southwest wind easing to moderate southeast in the afternoon / alpine high temperature near -4 / freezing level 800 m

SATURDAY - Mainly cloudy with scattered flurries / moderate south wind / alpine high temperature near -5 / freezing level 800 m

SUNDAY - Mainly cloudy with isolated flurries / light south wind / alpine high temperature near -4 / freezing level 800 m

Avalanche Summary

Storm slabs are expected to be reactive on Friday with new snow and strong winds creating conditions that are primed for human triggering.

On Wednesday there were several size 1-2 explosive triggered storm slabs and wet loose avalanches reported in the north of the region, somewhat close to the Ningunsaw area.

On Tuesday, a notable natural size 3 persistent slab avalanche was reported on a south to southwest aspect along the Highway 16 corridor between Terrace and Prince Rupert. It is suspected to have failed on the mid-February persistent weak layer. 

There was an ongoing natural avalanche cycle occurring throughout much of the region on Tuesday.

Last weekend a widespread natural avalanche cycle occurred up to size 3 and explosive control initiated numerous size 2-3 storm slabs and persistent slabs.

Snowpack Summary

60-100 cm of recent storm snow blanketed the region over the past week. This was accompanied by strong to extreme southwest winds which have formed deep wind slabs on leeward slopes. Massive cornices exist on ridgelines at treeline and in the alpine. 

There is now 100-200 cm over two persistent weak layers that were buried in mid-February and late January. These layers consist of surface hoar in areas sheltered from the wind, and facets that developed during the cold snap. These weak layers have been the cause of several large avalanches in the past week. 

There are currently no layers of concern in the mid and lower snowpack.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Avoid freshly wind loaded terrain features.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

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.