Avalanche Forecast

Issued: Apr 30th, 2017 4:24PM

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, Wind Slabs and Deep Persistent Slabs.

snow safety, Parks Canada

Banff Yoho Kootenay.

Pay attention to freezing levels this week. The first really big warmup is forecasted for Wednesday when freezing levels are expected to rise to 3000m.

Summary

Weather Forecast

Mixed sun and cloud with some convective flurries are forecast for Monday. Freezing levels will be around 2000 m on Monday and rising significantly to 3000m by Wednesday as an upper ridge moves into the region from the west.

Snowpack Summary

15 cm of overnight snow and 40-60cm of storm snow from this past week. There is moist surface snow and variety of melt freeze crusts in the upper snow pack in all areas except for due north above 2300 m. 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

Several fresh wind slab avalanches (up to size 2) were observed in the alpine on north aspects in the Field and Lake Louise area on Sunday. Loose wet avalanches and several slab avalanches (associated with day time heating) were also observed on Sunday.

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.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Wind Slabs

Recent winds have created soft wind slabs on north aspects in the alpine.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible - Likely

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

Unlikely - Possible

Expected Size

2 - 4

Valid until: May 1st, 2017 4:00PM