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Avalanche Forecast

Archived

Nov 22nd, 2012–Nov 23rd, 2012

Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.

Regions

South Rockies.

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

A Pacific frontal system will be dominating the coastal regions tonight. This system will move into the Interior regions on Friday bringing light –moderate snow accumulations.  Through the weekend a NW flow will set up, bringing cooler, dryer conditions and partially sunny skies. Freezing levels remain in valley bottom through the period.Friday: Alpine -5, snow 5-10 cm, winds SW 30 – SE 40 km/hr.Saturday: Alpine -10, snow 2- 5 cm, winds W 20 km/hr switching NW.Sunday: Alpine -15, snow 5 cm, winds NW 10km/hr.

Avalanche Summary

No current avalanche observations have been submitted. If you and your friends have been out exploring and riding in the backcountry, and have some observations to share please send us an email to [email protected].

Snowpack Summary

Snowpack observations and information are extremely limited, and conditions across the region vary. In the alpine I suspect anywhere from 50-100 cm of snow. Storms slabs and wind slabs likely exist in alpine and treeline elevations. An early season (Nov 8) rain crust has been reported to exist around 2000 m and above on NW-NE aspects. I have no further information in regards to this crust, how deep its buried or reactive it may be. I do know that it has been a reactive sliding layer in other regions to the North, which makes me suspect this problem may extend into the South Rockies.Snow depths at treeline are roughly sitting around 30-50 cm in depth, and below treeline snow levels may still be below threshold.

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.

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.