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Avalanche Forecast

Archived

Dec 2nd, 2012–Dec 3rd, 2012

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

Regions

South Rockies.

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

Overnight and Monday: Light precipitation overnight should bring 4-6 mm to most of the region, areas to the west may see closer to 10 mm. Very strong winds are forecast overnight, and strong winds are expected from the SW on Monday.Tuesday: The next Pacific system is expected to bring a lot of moisture to the south and west of the region. The north and east parts of the region may only see 5-10 mm. Strong winds and high freezing levels will affect the areas that see the most moisture.Wednesday: Precipitation amounts should be light in the wake of the storm and freezing levels should drop down to near the valley bottom.

Avalanche Summary

No recent avalanche observations.

Snowpack Summary

A report from near Harvey Pass tells us that there is about 25 cms of storm snow that is "damp" at treeline and the ski penetration is only about 20 cms. The November crust was found to be buried down about 60 cms and was associated with a layer of facets either directly above or below. Light winds were not transporting much snow in this area. Alpine elevations may be quite different, as most of the recent precipitation has fallen as snow. We are hoping that the storm snow will bond well as temperatures cool, this may still take a day or two.

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.