Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Nov 23rd, 2019–Nov 24th, 2019

Alpine
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.

Strong southwest wind combined with up to 20 cm of new snow is expected to form wind slabs which will be most problematic near ridge crest. The weak & highly variable snowpack will likely need time to adjust. Conservative terrain selection is prudent Sunday.

Confidence

Low - Uncertainties in both the snowpack structure and the weather forecast limit our confidence.

Weather Forecast

Saturday Night’s storm should offer the Purcells (especially the northern section) a nice re-fresh before we move into a period of high pressure next week.

SATURDAY NIGHT: Freezing level around 1100 m, moderate to strong west/southwest wind, 5 to 20 cm of snow possible.

SUNDAY: Broken cloud cover, freezing level around 1100 m, light to moderate northwest wind, 1 to 5 cm of snow possible.

MONDAY: Broken cloud cover, freezing level around 700 m, light variable wind, trace of snow possible.

TUESDAY: Scattered cloud cover, freezing level at valley bottom, calm, no significant precipitation expected.

Avalanche Summary

No recent avalanche activity has been reported. A natural avalanche cycle is possible late Saturday Night into Sunday as strong southwest wind and up to 20 cm of snow is forecast.

Snowpack Summary

Winter is slowly creeping down to the valley, but avalanche hazard is largely confined to the alpine at this time. Snowpack depths range from 10 to 100 cm. The young snowpack is higly variable due to previous wind transport and areas of shallow snow which are highly faceted. Most treeline and below treeline areas are probably below threshold for avalanches at this time. A pottentially problematic melt freeze crust from late October can be found above basal facets in the lower snowpack. There's a great summary of current conditions in the Golden area here.

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.