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

Feb 7th, 2013–Feb 8th, 2013

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

Regions

Northwest Coastal.

Confidence

Good

Weather Forecast

Friday: Expect clouds to build with flurries developing in the afternoon. 5-10cm are possible, focussed on west facing terrain. Winds should turn westerly and increase to moderate/strong values with alpine temperatures reaching -5.Saturday & Sunday: A ridge will build giving mostly clear skies, light west/southwest winds and alpine temperatures reaching -2 in the afternoons.

Avalanche Summary

The region saw a natural avalanche cycle. Natural slabs and cornice falls up to size 3.0 were reported, predominantly on north-northeasterly terrain. Many loose wet avalanches up to size 2.0 have occurred below treeline, where the recent precipitation fell as rain. Both explosive and rider controlled avalanches were observed up to size 2.5, predominantly in wind loaded areas. Some areas reported reverse loading from changing wind directions and have seen windslab failures in southeast facing terrain features.

Snowpack Summary

Recent weather has been relatively benign, with precipitation pulses giving incremental loading (5-10cm at a time). Relatively light winds have accompanied these snowfall pulses with some stronger outflow winds closer to the coast.Previous strong southwest winds gave intense snow transport and cornice growth. Extensive windslabbing in lee zones and behind ridges in the alpine and treeline was the result. Some areas saw swirling winds resulting in some cross and reverse loading on southeasterly features. These significant windslabs are now lightly buried.In the upper snowpack, a melt-freeze crust buried on Jan. 17 remains a concern. Recent compression tests show both resistent and sudden planar results and an extended column test shows a continued propensity for propagation if the layer was triggered. The Jan. 17th crust is down 60-100cm. It is certainly worth keeping this layer on your radar in regards to distribution and reactivity for the short term. The mid and lower snowpack is generally well settled.At lower elevations (below 700m), the drizzly rain is saturating and eroding the snowpack.

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.