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.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
Purcells.
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
Poor - Due to limited field observations for the entire period
Weather Forecast
Monday-Tuesday will with clear with sunny skies. No precipitation is expected, ridgetop winds will be light from the NW. Alpine temperatures will remain near -10 with freezing levels generally sitting near 800 m rising to 1100 m Tuesday. 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 1500 m, and winds will switch out of the South.
Avalanche Summary
No new information today. However, if the recent load did not produce avalanches, I would keep in mind that human triggering is likely. If you and your friends have been out riding in the backcountry, and have observations to share, please send an email to [email protected]
Snowpack Summary
The region received 15 to 30 cm of snow in the recent storm. Storm slab and wind slabs instabilities exist; however, with the current cooling dry trend this new snow may start to settle and bond. Wind loaded slopes that haven't produced avalanches already are my main concern for human triggering since two fairly deep persistent weak layers are found on all aspects and in the alpine and at treeline. The surface hoar layer is buried under approx. 60 cm, and the early season November crust is deeper, near the bottom of the snowpack ranging from 80 to 100 cm. The facet-crust layer is less reactive, however we do not have recent information about the sensitivity of the surface hoar layer. There is still a sharp transition in snow depth from treeline to below treeline making backcountry travel more challenging under the 1300 m range.
Problems
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.
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.