Archived

Avalanche Forecast

Apr 28th, 2018–Apr 29th, 2018

Alpine

Below Threshold

The avalanche danger rating in the alpine will be below threshold

Treeline

Below Threshold

The avalanche danger rating at treeline will be below threshold

Below Treeline

Below Threshold

The avalanche danger rating below treeline will be below threshold

Alpine

Below Threshold

The avalanche danger rating in the alpine will be below threshold

Treeline

Below Threshold

The avalanche danger rating at treeline will be below threshold

Below Treeline

Below Threshold

The avalanche danger rating below treeline will be below threshold

Alpine

Below Threshold

The avalanche danger rating in the alpine will be below threshold

Treeline

Below Threshold

The avalanche danger rating at treeline will be below threshold

Below Treeline

Below Threshold

The avalanche danger rating below treeline will be below threshold

Regions: Little Yoho.

Overnight rain will cause natural avalanches. While refreeze is expected up high by noon, The snowpack is unlikely to recover before Monday. A good day to avoid travel in the mountains.

Weather Forecast

Rain is forecast overnight Saturday and into Sunday. This, combined with the warm temperatures from last week will almost certainly preclude recovery and lead to high hazard in the morning. Temperatures will cool Sunday and will likely refreeze the snow at Treeline and in the Alpine. Isothermal snow can be expected below treeline throughout the day

Snowpack Summary

Isolated wind slabs are present in the alpine. Crust or moist snow on all solar aspects depending on temperatures. Buried temperature crusts to 2000m on all aspects and to ridge top on solar slopes, including the Mar 15 crust down 40-70 cm in the alpine. Moist snow at lower elevations, with the entire snowpack becoming moist near valley bottom.

Avalanche Summary

The last few days have seen many wet avalanches up to size 3 running on all aspects in the afternoon and early evening.

Confidence

Avalanche Problems

Loose Wet

Rain on a relatively warm snowpack will certainly cause avalanches overnight Saturday

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2.5

Persistent Slabs

A few deeper avalanches have occurred in the last few days. Some stepped down to the March 15 crust. On shaded aspects these were likely sliding on facets formed at the same interface. This will wake up again with intense heating or large triggers.

Pay attention to overhead hazards like cornices which could easily trigger persistent slabs.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2.5

Cornices

Cornice failures are occurring on a regular basis now with warm temperatures and intense solar inputs. These large triggers have caused failures on the persistent weak layers deeper in the snow pack in a few places in the last couple days.

Minimize exposure to overhead hazard from cornices.

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

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 3