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 12th, 2022–Mar 13th, 2022

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

Regions

Northwest Coastal.

Storms slabs may remain reactive to human triggers, especially in wind loaded terrain features. 

Choose simple terrain, and use small slopes with low consequence to test the bond of the storm snow.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

SATURDAY NIGHT: Mainly cloudy, isolated flurries. Light and variable winds are expected. Freezing levels drop to valley bottom. 

SUNDAY: A mix of sun and cloud. Isolated flurries possible. Light southerly winds becoming strong in the afternoon. Freezing level around 1000m. Alpine high -2. 

MONDAY: Snowfall begins overnight, around 10 cm by morning and another 10-20 cm possible over the day. Freezing levels around 1000 m. Alpine high -3. Strong southwest winds. 

TUESDAY: Light snowfall continues, up to 10 cm possible. Moderate southwest winds. Freezing levels around 1000 m, alpine high of -2. 

Avalanche Summary

On Friday, as storm totals increased skier and naturally triggered slabs were reported to size 1.5. Increased reactivity was noted where storm snow overlies a crust. 

Natural wet avalanches occurred in steep terrain features below treeline to size 1.5 as freezing levels rose. 

Over the last 10 days, a few size 1-2 persistent slabs have been triggered on the buried weak layers described in the snowpack summary section. Avalanches were mainly triggered on North through East aspects, between 1200 and 1800 m. Recent activity suggests they are becoming less reactive with the last reported avalanche on Sunday the 6th.

Snowpack Summary

Storm totals have reached 20-40 cm. In exposed terrain, west-southwest winds may have redistributed this into wind loaded pockets. 

Storm snow sits over a crust on south facing slopes and on hard wind pressed surfaces in most other terrain. A layer of surface hoar may sit below the storm snow in very isolated and sheltered terrain features.

Low elevations have seen 5-15 cm of wet snow that sits over a widespread crust on all aspects below 1000 m.

Several weak layers sit in the upper/mid snowpack that have been recently reactive. A spotty layer of surface hoar buried early March is down 20-40 cm, with another surface hoar layer from late February is buried 35-60 cm deep, and is most prominent at treeline elevations. A thick crust from mid-February is buried 70-110 cm. The snowpack below is well consolidated.

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.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

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.