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

Dec 1st, 2012–Dec 2nd, 2012

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

Regions

South Coast.

Limited field observations and reports exist from this region. Conditions may be variable. It is important to be familiar with the snowpack and avalanche problems that may exist in your local mountains.

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

The recent weather pattern continues, with a very persistent deep low off the coast driving a moist, mild SW flow over the region. Moderate accumulations are expected through the forecast period, accompanied by moderate S-SW winds. Sunday: Fzlvl’s 1300 m, snow amounts near 5 cm, ridgetop winds S 20-30 km/hr, alpine temps -4.Monday: Fzlvl’s 1200 m, snow amounts 8-15 cm, ridgetop winds S 35 km/hr, alpine temps -4.Tuesday: Fzlvl’s 1300 m in the am then falling to 700 m in the afternoon, snow amounts up to 20 cm, ridgetop winds S 30 km/hr, alpine temps -5 falling to -8.

Avalanche Summary

No new avalanche observations have been reported.

Snowpack Summary

Continued pulses of light-moderate snow accumulations, and strong ridgetop winds. Storm slabs and new wind slabs will load a variety of weak surfaces. These surfaces consist of large surface hoar, a thin sun crust, surface facets. The new snow may have a poor bond to these underlying weaknesses. Below the surface, the mid-pack seems to be settled and bridging over the early Nov facet/crust. However, near the bottom of the snowpack under the crust exists large, low density faceted crystals.Snowpack tests from earlier this week showed sudden collapse ("drops") results on the early November facet/crust deep persistent weakness. Because this weakness is so close to the ground in most areas, associated avalanche activity will likely be limited to slopes with smooth ground cover (e.g. scree slopes, rock slabs, summer firn, glaciers, etc.). Be aware of triggering this layer from thin, rocky areas, this persistent weakness my be a low probability/ high consequence scenario.Below treeline the snowpack generally sits below threshold.

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.