Avalanche Forecast

Issued: Apr 16th, 2018 4:49PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Storm Slabs, Persistent Slabs and Loose Wet.

conrad janzen, Parks Canada

Banff Yoho Kootenay.

Winter conditions persist with more snow expected into Tuesday. The hazard is greatest near the divide where the most snow has fallen. Choose more conservative terrain and minimize overhead hazard until things have a chance to settle and bond.

Summary

Weather Forecast

Temperatures will remain relatively cool for the next few days, with freezing levels up to 1800m. Snowfall amounts of up to 15 cm near the divide are expected overnight and into Tuesday with a drying trend later in the day. Winds will switch to the West and increase into the moderate range on Tuesday.

Snowpack Summary

10-15 cm of new snow with light winds. Up to 40 cm of storm snow near the divide. Several buried temperature crusts exist to 2000m on all aspects and to ridge tops on solar slopes, including the Mar 15 sun crust down 35-50 cm in the alpine. Moist snow at lower elevations, with the entire snowpack becoming moist near valley bottom.

Avalanche Summary

Some sluffing in the alpine on Monday. Reports of several natural slab avalanches out of steep alpine terrain near the divide up to size 2 in the past 24 hrs. Several skier triggered storm slabs reported near the divide at treeline and above, up to size 2 in the past 48 hrs. Loose wet avalanches up to size 2 at lower elevations in the past 48hrs.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Problems

Storm Slabs

20-50 cm of storm snow has fallen over the past few days with the greater amounts near the divide, and more is expected on Tuesday. This is settling quickly but wind loaded areas and steep terrain will be suspect for the next couple days.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

While it has been several days since there have been any confirmed events directly associated with the March 15 crust, other temperature crusts have now become buried in similar locations and are providing a good sliding layer for the new storm snow.

Be cautious with convexities and steep slopes on solar aspects.The storm slab may be more sensitive to human triggering on solar aspects where it sits on a crust

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

Lower elevations may see loose wet avalanches start to occur later in the day with either temperature increases or rain as the storm finishes on Tuesday.

Use extra caution on slopes if the snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Apr 17th, 2018 4:00PM