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

Feb 12th, 2020–Feb 14th, 2020

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

North Rockies.

Ongoing stormy weather will maintain elevated avalanche danger through the second half of this week. Pay attention to new snow amounts and avoid wind-affected slopes. Areas that receive 25 cm or more new snow in a 24 hour period should consider the avalanche danger to be HIGH.

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

Wednesday night: 10-15 cm new snow focussed on the west of the region. Strong southwesterly winds.

Thursday: 10-15 cm new snow. Strong southwesterly winds. Freezing level around 800 m.

Friday: 10 cm early morning with snow easing by mid-morning. Moderate westerly winds. Freezing level lowering to surface with treeline temperatures around -6C. 

Saturday: 10 cm new snow. Moderate southwesterly winds. Treeline temperatures around -3C.

Avalanche Summary

A few loose snow avalanches were reported from the Torpy on Monday.

With new snow and wind in the forecast, I anticipate natural and human-triggered avalanches will increase in likelihood toward the end of this week.

Snowpack Summary

A layer of surface hoar appears to have become buried by light snow. We don't know too much about the distribution of this layer and it may have been impacted by strong winds in some areas. It is buried approximately 40 cm in the south of the region and 10-20 in areas further north and east. Initially the bond at this interface was reported to be reactive. However, cold overnight temperatures appear to have improved the strength at this interface.

Slightly lower in the snowpack, approximately 40-60 cm below the surface, there is a thin rain crust from the warm, wet storm on Feb 01. This rain crust has been reported to exist up to treeline elevations around 1700 m. Initially this layer was described as reactive and was the focus of a number of avalanches. However, it now appears to be gaining strength and probably won't end up being a significant long-term weak layer.

In the mid-pack there may still be a layer of surface hoar buried in late December. It's gaining strength, but should remain a concern since snowpack tests still demonstrate this layer has the potential to slide, albeit in isolated areas and/or with very large triggers.

Terrain and Travel

  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • Cornice failure may trigger large avalanches.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.