Avalanche Forecast

Issued: May 2nd, 2017 4:00PM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Loose Wet, Deep Persistent Slabs and Cornices.

ian jackson, Parks Canada

Banff Yoho Kootenay.

Get up early and take advantage of the last good freeze for a while. We are expecting a widespread avalanche cycle with the forecasted warming temperatures on Thursday and Friday!

Summary

Weather Forecast

Tuesday should see a good overnight recovery with freezing levels to ~1200m. Freezing levels will rise to 3000m by Wednesday PM with no overnight recovery, further rising to 3500m the next morning. Skies should be mostly sunny with the occasional flurry/shower and winds are forecasted to increase to moderate SW through the day on Wednesday.

Snowpack Summary

Dry snow still exists on high north aspects. Moist surface snow and a variety of melt freeze crusts exist in the upper snow pack on all other aspects and elevations. A basal weakness remains at the bottom of the snow pack. It is currently only reactive to large triggers but may wake up with solar warming.

Avalanche Summary

A size 2 out of a low alpine (2400m) rocky solar aspect failed to ground today in the Sunshine backcountry. 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

Problems

Loose Wet

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

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

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The weak basal facets can produce large avalanches with large triggers or heat. Remember that the snowpack is generally strongest in the morning when it is cool.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Cornices

Cornices are big this time of year and will fall off at some point in the next few weeks. Warm temperatures and sun may be the trigger, so minimize your exposure during these times.

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

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: May 3rd, 2017 4:00PM