Avalanche Forecast

Issued: Nov 17th, 2015 6:52PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Avalanche control planned for Sunshine tonight, Bosworth, and Mt. Stephen on Wednesday. Depending on results we may also do Simpson, Whymper, and clean up on Sunshine. Please no recreational activities in these areas on Wednesday.

Summary

Weather Forecast

The cold front passes by midnight: the snow should end, temperatures continue to drop, and winds should taper. For Wednesday, expect isolated flurries and light winds from the W gusting to 50 km/hr. Stable weather is forecasted for the remainder of the week with 2 nights of -18C temperatures (Thur & Fri) and warmer for the weekend (-12C).

Snowpack Summary

Essentially 2 major snowfall events in the past week has created the snowpack. The midpack is supportive, but not glued to the ground very well with two column test failures at the ground level on Monday. A layer of surface hoar exists 15-20 cm off the ground, but no test results were found on this layer.

Avalanche Summary

Visibility has been poor today, but some avalanches were heard. Today ski cutting around Sunshine produced only small surface avalanches with nothing stepping down. This may change with more load overnight from snow and wind. We expect natural avalanche activity to continue tomorrow with moderate W winds adding load to the weak layers.

Confidence

Problems

Wind Slabs

Strong winds have been redistributing the loose snow into leeward areas where windslab failures should be expected in the upper 80 cm on leeward terrain. Continued moderate SW wind Wednesday will add to the load causing natural avalanches.

The new snow will require several days to settle and stabilize.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Storm Slabs

The entire snowpack is a result of 2 recent storms. Surface hoar and facets lye at the base of this storm snow where only a few days ago produced a few alarmingly large avalanches. It was becoming less reactive, but tonight's storm may wake it up.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Nov 18th, 2015 4:00PM