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Avalanche Forecast

Archived

Mar 24th, 2025–Mar 25th, 2025

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

Banff Yoho Kootenay, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

We anticipate an avalanche cycle on Tuesday and Wednesday as freezing levels rise to 2500 - 3000 m and the sun comes out on Wednesday. This, plus 5-10 cm of snow and rain to treeline on Tuesday will increase the likelihood of avalanches. Avoid avalanche terrain on both days and expect better conditions starting Thursday as it cools.

Confidence

Moderate

Avalanche Summary

Lake Louise and Sunshine ski resorts both reported numerous surface windslabs up to size 1.5 in leeward areas. Additionally, Sunshine reported a large (size 3) deep persistent slab in north-facing terrain at 2500 m elevation that started as a windslab, then propagated a 200 m wide fracture line that ran down into mature timber. This kind of large, deep avalanche should be expected over the next few days with the warm temperatures.

Snowpack Summary

Over the past few days, 15-20 cm of moist (heavy) new snow has been blown into windslabs up to 40 cm deep in leeward areas. This adds to the dense slab, 50-100 cm thick, overlying weak facets in the mid to lower snowpack and is responsible for the recent large avalanches. This condition has been most sensitive in the Bow Summit area, but expect the likelihood of avalanches to increase at all elevations with the warming.

Weather Summary

Warm air continues to invade the region on Tuesday, accompanied by 5-10 cm of snow which may turn to rain on Tuesday afternoon. Valley bottom temperatures in Lake Louise will hit +10 on Tuesday and +13 on Wednesday when the sun comes out. Freezing levels will peak on Wednesday between 2500 - 3000 meters.

Terrain and Travel Advice

  • Make conservative terrain choices and avoid overhead hazard.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.

Problems

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.

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.