Archived

Avalanche Forecast

May 3rd, 2017–May 4th, 2017

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: Banff Yoho Kootenay.

Expect no overnight freeze for the next few days (freezing levels to 2800 m tonight and higher Thurs. night). Larger avalanches may occur with incoming hot weather - be mindful of terrain overhead. The hazard will quickly climb to HIGH on Thursday.

Weather Forecast

Freezing levels will rise to 3000m by tonight with no overnight recovery, rising through tomorrow to 3600m for Thursday night. Expect a mix of sun and showers with light to moderate SW wind for Thursday - Friday.

Snowpack Summary

Dry snow still exists on high north aspects. Moist surface snow and a variety of melt freeze crusts other aspects and elevations. Unsupportive isothermal conditions to 1900 m. A basal weakness remains at the bottom of the snow pack - reactive to large triggers but may wake up with the incoming warm weather, 2800 m freezing level, & solar input.

Avalanche Summary

Wind kept things cool most of the day, only some loose wet late to size 1.5 late in the day on S-W aspects in the alpine. This was caused by a combination of warm ambient air temperatures and rocks in the slope absorbing the sun's radiation and additionally heating the slope.

Confidence

Avalanche Problems

Loose Wet

Loose wet avalanches can be expected on solar aspects in the afternoon when the day warms up.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.Pay attention to sluffing off cliffs and steep solar terrain, signs of a warming snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 3

Deep Persistent Slabs

The weak basal facets can produce large avalanches with large triggers or heat. There will be no substantial recovery for the next few nights.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 2 - 4

Cornices

Cornices are big this time of year and will fall off at some point in the next few weeks. They will be more frequent with the forecasted warming and solar effect over the next few days.

Cornices become weak with daytime heating, so travel early on exposed slopes.Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood: Likely - Very Likely

Expected Size: 2 - 3