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Avalanche Forecast

Archived

Dec 7th, 2020–Dec 8th, 2020

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

Regions

Purcells.

The danger rating reflects forecast snowfall amounts near Golden. For most of the region, where less than 5 cm of new snow falls, avalanche danger will remain LOW at all elevations.

Confidence

Low - Uncertainty is due to the track & intensity of the incoming weather system.

Weather Forecast

Monday night: Up to 10 cm new snow in the north of the region, flurries elsewhere. Light to moderate southwest wind, freezing level 700 m.

Tuesday: Up to 5 cm new snow in the north and west border, flurries elsewhere. Light to moderate southwest wind, freezing level 1000 m.

Wednesday: Up to 5 cm new snow, light west wind, freezing level 1000 m.

Thursday: Flurries, light west wind, freezing level 700 m.

Avalanche Summary

Results from explosive work were limited to size 1 loose dry out of rocky terrain Sunday.

Small loose dry sluffing may be observed in the new snow Tuesday. Storm slabs may be triggerable in wind loaded lee features at upper elevations.

Our eyes and ears in the mountains are limited this winter due to fewer professional observations. If you go out in the mountains, please share your observations on the Mountain Information Network (MIN). Photos are especially helpful! Thank you so much for all the great MINs submitted so far! 

Snowpack Summary

Around 5-15 cm of new snow falls ontop of a melt-freeze crust on south aspects and widespread surface hoar treeline and below. Generally speaking, new snow does not bond well to these types of surfaces.

The lower snowpack is characterized by a couple of crusts, the most notable of which is sitting near the base of the snowpack, likely surrounded by a weak layer of sugary facets. It is most likely to be reactive to human triggers on south facing slopes and in shallow, rocky areas in the alpine.

Terrain and Travel

  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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.

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.