Avalanche Forecast

Issued: Mar 18th, 2021 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Loose Wet and Loose Dry.

mark herbison,

Banff Yoho Kootenay.

Poor overnight crust recovery and rain at lower elevations would make for a grim start to your day.

Snow at higher elevations will bury crust and surface hoar. Sluffs could have high consequences.

Watch for small pockets of wind slab at ridge top.

Summary

Weather Forecast

Mainly cloudy over the region with snow accumulations of 5-10cm along the Continental Divide (less to the East) over the day Friday and into the evening. Expect periods of rain below the 1900m freezing level with a valley bottom high of +8. Ridge top winds will be 20-60km/hr from the SW. Cooler temps and additional snow into Saturday.

Snowpack Summary

Sun crust on steep solar aspects (East to West) into the Alpine and a temperature crust on all aspects below 1800m. Soft snow still available on high North aspects. Surface hoar up to 10mm has formed in isolated, shaded areas and will become a failure layer for future snow falls. Otherwise the snowpack is relatively strong and well settled.

Avalanche Summary

Several loose wet avalanches hit the Field Back Road over the past 48 hours (The Descent Gully for Guinness)

Lake Louise ski area reported 2 skier controlled wet loose avalanches, sz 1.5 and sz 2.0 late in the afternoon on Thursday in steep, rocky terrain below tree line.

Confidence

Problems

Loose Wet

An overnight freezing level of 1800m and forecasted rain at lower elevations does not bode well for the snowpack at tree line and below. There will be minimal crust recovery overnight and the snowpack will loose strength quickly.

Use extra caution on slopes if the snow is moist or wet.
If triggered, loose wet sluffs may step down to deeper layers resulting in larger avalanches.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Dry

Snowfall amounts of 5-10cm will fall on sun crust on steep solar aspects into the alpine, a temp crust below 1800m on all aspects and surface hoar 5-10mm in isolated shaded areas. Sluffs in steep, confined terrain could have severe consequences.

Be careful of loose dry power sluffing in steep, confined or exposed terrain.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Valid until: Mar 19th, 2021 4:00PM