Avalanche Forecast

Issued: Mar 30th, 2018 4:00PM

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

conrad janzen, Parks Canada

Little Yoho.

With 20cm of fresh, Saturday looks like a great day to be out in the mountains, but the avalanche risk is elevated due to Friday's storm. Stick to more conservative terrain choices until better information is known about how the new snow is bonding.

Summary

Weather Forecast

A clearing trend is expected on Saturday with light winds and cool temperatures between -10 and -15'C during the day. Sunday will see a 3-5 cm's of new snow, continued light winds and slightly warmer temperatures.

Snowpack Summary

15-20 cm of new snow on Friday with strong W winds has formed wind slabs in lee features down to treeline. The March 15 sun crust is down 30-50 cm on solar aspects and has been sensitive to skier triggering over the last week. The mid- pack and basal layers have been dormant.

Avalanche Summary

Some explosive triggered wind slabs up to size 2 where observed at the local ski areas Friday but observations were limited. Thursday there were a few cornice triggered wind slabs up to size 2 in the Bow Hut area and Sunshine Village. Several skier triggered slides on steep solar aspects have occurred in the past week on the persistent sun crust.

Confidence

Due to the number of field observations

Problems

Wind Slabs

The new snow Friday arrived with strong SW winds and formed wind slabs in lee areas. Some older wind slabs will now be buried in specific features at upper elevations as well. This new snow will need a few days to settle and bond.

Use caution in lee areas in the alpine and treeline. Recent storm snow has formed wind slabs.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Persistent Slabs

The buried March 15th sun crust is down 25-50cm and has provided a good sliding layer for several skier triggered avalanches over the past week. The new snow load may make this more touchy so avoid steep solar aspects until this has a chance to bond.

Watch for signs of instability such as whumpfing, or cracking. Dig down to find and test weak layers before committing to a line.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Mar 31st, 2018 4:00PM