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Avalanche Forecast

Archived

Nov 24th, 2012–Nov 25th, 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 Forecaster Blog for further details on interpreting early season bulletins.

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

The weather is doing a shift from a fairly active pattern to a more benign pattern through the forecast period. A cooler, dryer NW flow will be entering the mountains with patches of lower level clouds and sunny periods in the alpine. Freezing levels will stay near valley bottom, rising to 1200 m in the afternoons. Ridgetop winds will moderate be light from the NW, switching to a Westerly flow on Tuesday.

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

In the alpine I suspect 100 + cm of snow, and treeline seeing an average around 90 cm. 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 could be a problem also in the South Rockies. In the alpine I suspect 100 + cm of snow, and treeline seeing an average around 90 cm. Below treeline snow levels may just be reaching 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.