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

Apr 11th, 2015–Apr 12th, 2015

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

Regions

Northwest Coastal.

Wind effect in the alpine and a treeline are of prime concern with this storm, use caution when riding/traveling in the backcountry. If you have field observations to share here we'd love to hear from you.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

SUNDAY: Will ramp up precipitation with another 8 to 10 cm of snow at upper elevations. Freezing levels 500m overnight to 800m with daytime heating. MONDAY: Another 5 to 10 cm of snow. Precipitation will be heavier towards the coast, but the inland portion of the Northwest Coast may see as much as 45 cm of snow at upper elevations through the forecast period.TUESDAY: A brief break in the weather, cloudy with sunny periods, some flurries with freezing levels from 500 to 800m. Winds moderate to strong from the south west for the forecast period.

Avalanche Summary

Commercial operators are reporting strong winds in the alpine stripping the new snow down to old crust surfaces and building wind slabs and sastrugi. One operator has reported numerous size 2 and 2.5 avalanches with explosives control.

Snowpack Summary

New snow is being redistributed by strong south west winds into wind slabs on lee slopes. Reports of activity on the March 25th surface hoar / crust layer have diminished, but is still worth remembering. This interface was more reactive recently in the northern part of the region, but had been reported throughout the northwest coastal area and may reappear as a problem given the right conditions. For the most part, the chief concern is wind slabs over a variety of recent surfaces, crusts, facets and surface hoar that formed in in sheltered places during the last spell of clear cold weather. Large ripe cornices are also of concern with additional loading, especially when the sun and warm temperatures come back.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.