Avalanche Forecast

Issued: Nov 24th, 2017 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

Conditions are improving after Thursdays monsoon, but there is still uncertainty around the persistent slabs and how reactive they are, especially above 2500m where the rain line ended. SH

Summary

Weather Forecast

Another 5 cm possible on along the divide on Saturday with lesser amounts on the Eastern slopes. Winds will be in the moderate range from the SW and temperatures will go above zero in Banff and stay just below freezing further into the mountains. On Sunday another 5-10cm is expected with increasing winds.

Snowpack Summary

There is up to 75 cm new in the alpine from the last week with specific wind slab development on lee aspects. Below approx. 2600 there is a new Nov.23 rain crust forming from the torrential rains Thurs. The concern before the storm was the Halloween crust and/or facets near the bottom of the snowpack,which may now be of most concern in the alpine.

Avalanche Summary

Activity has slowed dramatically after the big rain event Thursday which saw natural and man made avalanches up to size 3 which were a combination of persistent slabs and loose wet avalanches. Lake Louise ski hill was reporting some explosive controlled persistent slab results to size 2 today in alpine features.

Confidence

Due to the number and quality of field observations

Problems

Persistent Slabs

Terrain at higher elevations did not get the rain from Thursdays storm and the halloween facets/crust will still be reactive to human triggering with a thicker slab on top.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

There has been lots of new snow up high over the past few days, and some wind slabs have been noted on lee aspects that in the short term may still be reactive. So far, reports from the field have reported these wind slabs to be "stubborn" in nature.

Avoid freshly wind loaded features.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Nov 25th, 2017 4:00PM