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Avalanche Forecast

Archived

Feb 21st, 2025–Feb 24th, 2025

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

Waterton Lakes, Waterton.

We are in a period of change with significant warming this week and between 15 - 35 cm of new snow over the next few days.

The new snow will fall on a relatively weak snowpack - make conservative terrain choices this weekend until the new snow stabilizes and we understand better how the persistent layer will react to this new load.

Confidence

Moderate

Avalanche Summary

On Wednesday, a few natural windslabs in steep slopes below cliffs were observed, and one natural size 2 slab avalanche which we suspect was a persistent slab.

Snowpack Summary

15 - 35 cm of new snow is expected to fall over the weekend and into Monday.

Strong southwesterly winds are building windslabs at all elevations. The January drought layer is 30 - 60 cm down. This layer includes facetted snow on northerly aspects or a melt freeze crust below treeline and on steep solar slopes into the alpine. Generally, the snowpack is weak and facetted.

Snowpack depths at treeline range from 100 - 160 cm.

Weather Summary

Warm temperatures and strong winds continue with up to 35 mm of precipitation by Monday. See table for details.

Check out the Mountain Weather Forecast for the most up to date information.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.

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.

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.

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.