Avalanche Forecast

Issued: Mar 12th, 2017 4:00PM

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

aaron beardmore, Parks Canada

Banff Yoho Kootenay.

A warming trend is producing uncertainty as to how deep persistent slabs will react in the coming days.

Summary

Weather Forecast

Cloud cover and very light precip (<10cm) is forecasted for the next few days. However, wind is expected to be, at times, in the strong range from the west. Temperatures will likely be just below zero at 2000m for the next 24 hours.

Snowpack Summary

60-80cm of storm snow settling with warmer temps has been reactive this past week. Expect moist snow on solar aspects below treeline due to warmer temps and sun. Wind slabs have formed in alpine lee areas. Below this storm snow a more settled slab sits over the weaker facets and depth hoar near the base which is widespread.

Avalanche Summary

A size 2.5 deep persistent slab avalanche was observed on Fossil Mountain today near Skoki Lodge. The slide covered the trail to Cyclone cabin and pushed right up to the trim line. With recent storm snow and warming temps, there was surely much naturally activity through out the region today.

Confidence

Freezing levels are uncertain on Wednesday

Problems

Wind Slabs

60-80cm of dry snow from the past week is being blown into cohesive wind slabs at higher elevations. Warmer temperatures will help settle these out and become less reactive, but it may take a few days for the snowpack to fully adjust to the new load.

Be aware of the potential for wide propagations.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

The entire snowpack is built upon a structurally weak base, which can produce very large avalanches. Recently, large deep persistent slabs have been observed, suggesting that likelihood of triggering is increasing.

Be aware of thin areas that may propogate to deeper instabilites.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Mar 13th, 2017 4:00PM