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Avalanche Forecast

Archived

Mar 17th, 2024–Mar 18th, 2024

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

Regions

Kananaskis, Bow Valley, Highwood Pass, North 40, Spray - KLakes, Ghost.

A weak freeze overnight (especially at higher elevations) and a slightly cooler day on Monday should lead to decreased avalanche activity. However, keep an eye on localized conditions as any significant solar input will drastically increase the avalanche hazard. Be aware of overhead terrain and time your travel to be out of avalanche terrain before the day warms up.

Confidence

Moderate

Avalanche Summary

A widespread natural cycle continues with a loose wet avalanche cycle to size 1.5 on all solar facing terrain to mountain top. A couple new slabs were noted on steep East facing terrain below cliffs that were likely cornice triggered.

Avalanche activity should decrease on Monday with slightly cooler temps and cloudier skies.

Snowpack Summary

Warm temperatures are settling the upper snowpack and creating moist snow up to 2200m on all aspects and likely over 3000m on solar aspects. This new snow is settling and in some places overloading the weak layers triggering natural avalanches that are either failing on the ground or on the February crust down 60-90cm. Polar aspects in the alpine may still hold dry snow but isolated wind slabs should be expected if you are headed into this area. With our generally weak snowpack and the big pulse of heat, its a good time to avoid avalanche terrain in general. Extensive settlements were heard on Friday while travelling in any open areas indicating the snowpack is highly susceptible to human triggering. Avalanches have the potential to go full path reach all the way down to the valley floors. Cornices are large and looming over many features at this time of year and with the heat, they may act as a big trigger on underlying slopes.

GHOST FORECAST AREA

The Ghost area has more snow than usual. With this warming trend, pay close attention of what is above you. Wet loose avalanches and cornice failures are possible in this forecast region. Ice climbers should choose routes appropriately. Check out a recent MIN for more details.

Weather Summary

Freezing levels will again remain elevated on Monday, but not quite as high as the last couple of days. Temperatures will reach +1C with freezing levels near 2100m. A temperature inversion is likely, so despite cooler overnight temps in the valley floor, treeline elevations (2200m) may not freeze. Clear skies mean that the mid-March sun will pack a punch. Winds will be moderate from the NW at ridgetop.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Cornices become weak with daytime heating or solar exposure.
  • Extra caution for areas experiencing rapidly warming temperatures for the first time.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.

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.