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Avalanche Forecast

Archived

Nov 25th, 2012–Nov 26th, 2012

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

Kootenay Boundary.

This bulletin is based on limited data. Local variations in conditions are likely to exist. Check out the Forecasters Blog for further details on interpreting early season bulletins.

Confidence

Fair - Due to limited field observations for the entire period

Weather Forecast

Monday-Tuesday will see patchy valley cloud in the mornings with clear, sunny skies in the afternoon.  No precipitation is expected, ridgetop winds will be light from the NW. Alpine temperatures will remain near -4 with freezing levels generally sitting near 800-1100 m. Wednesday should start to see a change as the next system sets up. Timing and intensity of Wednesdays system is uncertain.  Freezing levels may climb to 1900 m, and winds will switch out of the South.

Avalanche Summary

No new avalanches were reported. If you and your friends have been out exploring and riding in the backcountry, and have some observations to share please send an email to [email protected].

Snowpack Summary

The previous storm has formed new storm slabs which may have buried existing wind slabs. Storm slabs may be touchy and easy to trigger and may take a couple days before they settle out. An early November crust is located near the bottom of the snowpack under the past weeks snow accumulations.  This crust has been seen from 1700 m to ridgetop on all aspects. Recent tests done have resulted in CTM-H ranges with SP characteristics. I have also received reports of a SH layer buried 100 cm down. The SH sits about 10 cm above the November crust and is 3-4 mm in size. Tests on this layer are in the mod-hard range with a SP characteristic. At this time the SH may just be localized and not widespread, not sure?  Dig down, do some detective work, and see how the snowpack is looks, feels and reacts in your neck of the woods. 

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.