Avalanche Forecast

Issued: Apr 5th, 2017 4:00PM

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

grant statham, Parks Canada

Banff Yoho Kootenay.

The next big warm-up comes this way starting on Wednesday evening and continuing through Friday. The snowpack is unlikely to re-freeze overnight, and with continued rain and snow, the conditions will not be great for the next couple of days.

Summary

Weather Forecast

A series of warm low pressure systems are moving across BC and AB starting Wednesday night and continuing through Thursday evening. For Thursday expect freezing levels to 2300m, with treeline temperatures at +2. Rain in the valley bottom and snow above 2000m may accumulate 10cm before it stops. Friday will be cloudy and warm.

Snowpack Summary

A settled, mostly dry snowpack exists on shaded aspects above 2300m. On other aspects and below 2300m, expect morning crust and wet snow by mid-day. The base of the snowpack continues to be unstable with a layer of facets failing approximately 60cm above the ground. For this reason, most avalanche prone slopes are out unless they have already slid.

Avalanche Summary

No new avalanches were observed or reported today (teams on the western side of the Wapta and at the Sunshine Village area).

Confidence

Freezing levels are uncertain on Thursday

Problems

Deep Persistent Slabs

The snowpack is generally unstable, despite the strong feel of the surface layers. This next warm-up will again test the snowpack and we expect increased avalanche activity over the next several days. Patience is a virtue with this kind of problem.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 4

Cornices

April is cornice season, and we are getting regular reports of cornices failing. Mature cornices can propagate much further than you expect, so give them a wide margin when traveling on ridges and get up early and hurry if you must travel below them.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Wet

Wet snow flows like water in gullies during warm spring days, and the next few days we expect wet snow avalanches to be common in gully areas at and below treeline. Ice climbers - avoid steep low elevation gullies.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 6th, 2017 4:00PM