Avalanche Forecast

Issued: Mar 10th, 2016 4:03PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Deep Persistent Slabs and Wind Slabs.

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Avalanche Control planned for Friday on Mt. Bosworth, Stephen, Field and Dennis. Please no recreational activities in these areas on Friday. Thank-you.

Summary

Weather Forecast

Snowfall will taper off Thursday night and winds should back off through the morning Friday. Freezing levels to 1600 m. Expect sunny periods Friday and flurries on Saturday.

Snowpack Summary

20 -35 cm of new snow over the past few days overlies buried sun crusts on solar aspects. Moist snow exists up to 1700 m. Recent moderate S-SW winds with strong gusts have formed slabs in lee areas. A firm upper snow pack sits over a weak mid-pack of facets & depth hoar. In thin snowpack areas tests results are typically collapses near the ground.

Avalanche Summary

A few cornice collapses triggered size 1.5 avalanches in the Sunshine area, otherwise no new avalanches reported, but visibility has been poor. A couple of recent close calls are worth remembering however: last Monday a skier accidental size 2.5 on the Collie Glacier and on Sunday a skier accidental size 2.5 near Bow Summit.

Confidence

Due to the number of field observations

Problems

Deep Persistent Slabs

The mid-pack facets remain weak, especially in thin or rocky areas. Avoid steep or unsupported terrain, and watch for signs of instability such as whumphing and cracking. This weakness will be present for some time and is stressed with new snow load.

Caution around convexities or areas with a thin or variable snowpack.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

Recent W winds and new snow have created soft slabs in leeward ares near ridge crests. Pay attention to the snow surface conditions while touring - you can usually detect wind slabs easily and avoid these spots.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 11th, 2016 4:00PM