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Archived

Avalanche Forecast

Mar 25th, 2017–Mar 26th, 2017
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Little Yoho.

The sun will pack a punch at all elevations Sunday, be weary of overhead terrain on ice climbs that is exposed to solar inputs. Starting early and finishing early is recommended.

Weather Forecast

A diurnal weather pattern is forecasted for Sunday, Monday with daytime highs at valley bottom approaching 10 degrees and lows below freezing. Expect short convective pulses bringing in snow and rain, with mostly clear skies Sunday.

Snowpack Summary

100cm of dense, rounded snow comprises the upper half of the snowpack and sits on a variety of different foundations depending on location. In shallow areas (eg: Field ice climbs) the base is weak depth hoar. In deeper areas (eg: Little Yoho Valley), the base is rounded and stronger. Shears persist in the deep facets, and within the storm snow.

Avalanche Summary

The natural activity has decreased over the last few days however daily reports of activity continue to come in, Na size 3 observed on 93S in the Numa falls area suspect cornice trigger today. It appears to take only very small inputs of sun, wind or precip to trigger natural events and artificial / human triggering should be considered likely.

Confidence

Avalanche Problems

Persistent Slabs

Natural activity is starting to taper, but the snowpack is considered very suspect right now. Large avalanches initiating TL and above have recently run to valley bottom with crowns up to 2m + deep and several hundred meters in length.

  • Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
  • Be wary of slopes that did not previously avalanche.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 3 - 4

Wind Slabs

Wind transport was significant Thursday and has continued to a lesser extent Friday. Expect the fresh slabs that have formed at higher elevations to be easy to trigger. Expect the new growth on cornices to be fragile.

  • If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.
  • Pay attention to overhead hazards like cornices which could easily trigger persistent slabs.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Loose Wet

Strong solar inputs and increased daytime highs will deteriorate the snowpack structures below tree line. Take note of overnight refreezes, and strength of the sun effect on steep solar aspects.

  • Avoid ice climbs exposed to steep rocky terrain on solar aspects during the middle of the day.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 2