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Avalanche Forecast

Archived

Feb 23rd, 2023–Feb 24th, 2023

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

Regions

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

Gusty and shifting wind patters tomorrow will make it tough to travel with confidence. Sheltered areas on north an west aspects are the best bet for soft snow.

Confidence

Moderate

Avalanche Summary

Several old avalanches were noted today. A mid storm failure in the tent ridge area triggered the basal layers. The light was poor, but it may have been a sz3. In other areas, there were more recent alpine windslabs that failed in the past 24 hours. These were up to sz2, maybe 2.5.

Snowpack Summary

Sustained easterly winds have taken our storm snow and left us with a combo of wind effected snow and a disturbed surface in many areas. Low elevation sheltered (north & north west) aspects have likely escaped the windy wrath of this upslope/easterly weather pattern. We are concerned about reactive windslabs at treeline and expect those slabs could easily produce a size 2 avalanche. The alpine has its own set of problems. The most concerning is still the deep persistent layer which has become reactive this past week. Slightly less worrisome, is the wind slab problem. These are on all aspects and are still in the human triggering realm.

Weather Summary

Good news everyone! It looks like the cold air will start to push out overnight tonight. It's almost like it is scheduled. At midnight the winds will start to shift to a more typical westerly flow. Tonight's low is -33, but tomorrow's high will be -18 with very little cooling Friday night. As the winds flop around expect strong gusts and likely a few flurries tomorrow. No significant snow, just a few flakes.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.