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Avalanche Forecast

Archived

Feb 17th, 2023–Feb 20th, 2023

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

Regions

Waterton Lakes, Waterton.

Use careful assessment as the Mid January Crust begins to get buried deeper. This crust has weak facets above and below it.

The field team was able to find good skiing on mellow slopes in more sheltered areas. Ridge crests have been more dramatically affected by the wind.

Confidence

Moderate

Avalanche Summary

Several natural wind slab avalanches up to size 2 were observed while on a field day this week.

Thanks to all the great posts this week on the Mountain Information Network, keep it up!!!

Snowpack Summary

10-20 cm of new windslab sits atop of older wind slabs at treeline and above or on steeper exposed slopes below treeline. Extreme W winds in the last two weeks have scoured some windward slopes down to the Jan crust. The total snow depth above the crust at treeline is approx. 50-70 cm. The crust is widespread and exists up to 2400 m. We are starting to see weak crystals develop above the crust and have observed at least 1 size 2 avalanche on this layer in the park.

Weather Summary

Saturday

Partially cloudy with flurries through the day. Alpine temps steady around -5. Winds S-X SW

Sunday

Partially cloudy with flurries through the day. Alpine temps steady around -5. Winds S-X SW

Monday

Overcast with snow getting heavier through the day. Alpine temps climb to -2 with winds M-W.

Terrain and Travel Advice

  • Recent new snow may be hiding windslabs that were easily visible before the snow fell.

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.