Archived

Avalanche Forecast

Apr 23rd, 2018–Apr 24th, 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.

Start and finish early to minimize the avalanche hazard. Watch for solar effect on the slopes above you and for isolated wind slabs in the high alpine. Corn skiing is starting on solar aspects, with powder on due N aspects in the alpine.

Weather Forecast

Clear skies Monday night with a good refreeze overnight, but warming up Tuesday by mid-day with freezing levels to 2500m and increasing winds in the afternoon. Freezing levels stay a little higher Tuesday night and climb to 2500m again on Wednesday before spiking to 3400m on Thursday. No precipitation is expected during the next several days.

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

A skier triggered size 2.5 persistent slab avalanche occurred on Mt Fairview late in the day Sunday. It failed 40-50 cm down on a buried sun crust. Lots of loose wet avalanche activity on steep solar aspects starting by 1000 in the morning. Several cornice failures triggering deeper slabs up to size 3 have been observed in the past 48 hrs.

Confidence

Avalanche Problems

Loose Wet

Loose wet avalanches are starting by mid morning on steep East facing terrain. This pattern will continue for the next while as temperatures increase. Plan your day to be off steep solar aspects early and watch for sun effect on the slopes above you.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. Use extra caution on slopes if the snow is moist or wet.

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

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2

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.

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

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.Cornices become weak with daytime heating, so travel early on exposed slopes.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 3