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 3rd, 2021–Feb 4th, 2021

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.
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.

Recent new snow in the central and southern parts of the region has woken up persistent weak layer. Adopt a conservative approach to selecting terrain in the coming days.

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack. Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.

Weather Forecast

WEDNESDAY Night: Mainly cloudy with flurries, accumulation 5-10 cm, moderate to strong northwest wind, treeline temperatures around -15 C.

THURSDAY: Cloudy with flurries and accumulation 3-8 cm, strong northwest wind, treeline temperatures around -10 C.

FRIDAY: Isolated flurries, moderate northwest wind, treeline temperatures around -12 C.

SATURDAY: Cloudy with flurries, moderate northwest wind, treeline temperatures around -17 C.

Avalanche Summary

There have been numerous reports of shooting cracks and whumpfs in the past two days.

In the Renshaw area there were reports of several natural size 2-2.5 persistent slab avalanches running on surface hoar buried 40 cm on Tuesday. There were also reports of few size 2 suspected persistent slab avalanches running naturally in the lower alpine on north and east aspects.

In the Kakwa area on Wednesday morning there were reports of several size 1-2.5 naturally triggered wind slab avalanches in the alpine running on east and south aspects. 

Snowpack Summary

In the southern part of the region from the (Torpy area south) there is likely 15-30 cm of new snow that fell Monday through Tuesday. 

Down 30-50 cm there is likely a hard melt-freeze crust up to roughly 1600 m, weak and feathery surface hoar crystals above 1600m to the lower alpine. Otherwise the new snow sits on wind packed snow in the upper alpine.

Additionally there may be a spotty weak layer of surface hoar 40 to 70 cm deep in sheltered treeline terrain in areas around Pine Pass. See this MIN post here.

There are presently no deeper concerns in the snowpack.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Choose conservative terrain and watch for clues of instability.

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.