Avalanche Forecast

Archived

Mar 19th, 2022–Mar 20th, 2022

Alpine

Natural avalanches possible, human triggered probable.

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

Kananaskis.

Crusts on solar aspect are becoming more the norm. Dry snow is found on the more polar aspects but watch for windslabs in alpine areas. The sun has got some strength to it these days so keep in mind intense solar radiation and its ability to destabilize the snow.

Confidence

Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

5-10cm of snow is forecast over the next few 24hrs with increasing winds out of the SW. Temperatures will again be dropping back into the cooler range with daytime highs on Sunday around -8C. Expect the sun to pack a punch tomorrow as clear skies are forecast and we can expect stability to deteriorate on solar aspects later in the day.

Avalanche Summary

One new cornice collapse on a N aspect near Burstall Pass parking area was observed. The cornice triggerred a sz 2 avalanche on the underlying slope that ran to valley floor.

Snowpack Summary

Moist snow was found on solar aspects above 2000m. On steep solar aspects, there are two crusts of concern. A crust was formed in early March and is found about 30-40cm down and was producing a hard clean sheer in only one pit dug. The Feb 19 crust is down about 60-80cm. There is still uncertainty with the reactivity of these crusts. Take the time to dig and evaluate these layers on steep solar aspects. Otherwise windslabs in alpine terrain should be expected from the recent SW flow and 10-15cm that fell throughout teh day on Friday. These slabs are widespread above 2600m and more isolated below this elevation to ridgelines and gullied terrain. The sun packs a punch these days and when it comes out, stability quickly deteriorates on solar aspects. These effects are most apparent on steep thin solar aspects. Numerous cornices collapses have recent been observed also as temperatures warm up.

Terrain and Travel

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
Be alert to conditions that change with elevation and wind exposure.
Wind slabs may be poorly bonded to the underlying crust.
Cornices become weak with daytime heating or solar exposure.

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.