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Avalanche Forecast

Archived

Dec 31st, 2012–Jan 1st, 2013

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

Regions

Northwest Inland.

Have a safe and fun new year!

Confidence

Fair

Weather Forecast

Monday night and Tuesday: The weak frontal systems weakens out and gives place to dryer conditions, moderate NorthWest winds switching to light SouthWest on Tuesday. Broken cloud cover is expected. Temperatures are expected to be quite mild in the alpine afternoon due to an inversion (above freezing levels between 1600 m. and 2400 m.)  Wednesday: A new frontal system is arriving which could give light to moderate amounts of precipitation with strong to extreme SouthWest winds. Thursday: The precipitations are expected to continue throughout the day and looks like winds could slow down considerably and temperatures cool off slightly as well.

Avalanche Summary

No recent avalanches were reported. A natural size 2 slab avalanche was observed in the Hankin area that would have happened around December 28th. Cornice fall is suspected to be the trigger. The slab happened on a North facing slope, it stepped down deeper in the snowpack, possibly on the November 6th crust. For more information check out the report here.

Snowpack Summary

Similar conditions as yesterday with a few more centimeters of snow. As a general overview, a shallow snowpack (about 1m deep) exists, with facets that have continued to develop at the surface of the snowpack and at the base of the snowpack in shallow and rocky areas. Strong winds have scoured some alpine slopes to ground. Wind slabs exist in many wind-exposed areas, however their distribution is quite variable and some areas have no wind-effect at all. Indeed, cold density snow is still possible to find at the surface in wind sheltered areas. Below treeline, very loose cold snow is sluffing easily from steep terrain and early season hazards like exposed stumps and rocks are still to watch for. Professionals are still mindful of a facet/crust layer near the base of the snowpack. Although triggering it has become unlikely, it may be possible from a thin-spot trigger point, with a very heavy load (e.g. cornice fall) or from a shallower slab stepping down to it. The natural slab avalanche that happened on December 28th is a good example of this concern.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.