Avalanche Forecast

Issued: Apr 7th, 2019 4:00PM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Wind Slabs, Loose Wet and Persistent Slabs.

aaron beardmore, Parks Canada

Banff Yoho Kootenay.

Recent snow and wind has created fresh windslabs in many leeward alpine locations. Take note that many small slabs were observed in steep couloirs on Saturday.

Summary

Weather Forecast

A clear-ish morning will be followed by increasing cloud and light precipitation. Light precip will continue until late on Wednesday when a front will deposit up to 15cm of new snow. Throughout the period, temperatures at the valley bottom will be just above zero.Â Wind will remain in the Mod/Strong (West) range through tonight and then dissipate.

Snowpack Summary

Up to 15cm recent snow at upper elevations. Melt-freeze crusts are common. On North and East aspects in the alpine, up to 30cm of unconsolidated snow can be found. Below this, a stiff slab overlying weak facets remains a concern in some places and a weak, faceted snowpack, remains a concern in thin areas.

Avalanche Summary

On a flight to the Wapta Icefields and through the Lake Louise group, forecasters observed several size 1 windslabs. These were typically on North aspects on alpine features, and often were observed having pulled out at the top of fans (bottoms of couloirs). While risk of burial is low, the risk of being carried to an undesirable location is there.

Confidence

Problems

Wind Slabs

A period of strong wind overnight on Saturday has created slabs in lee features in the alpine. Of note, evidence of these slabs was observed at the base of cones that are situated below couloirs. The windslabs were small in size (max size 1).

Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Loose Wet

The new snow will react notably with localized solar input, so position yourself away from steep features while the sun is beating down. This is particularly relevant at higher elevation where recent snowfall amounts are greater.

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

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 1.5

Persistent Slabs

A hard slab sitting over weak facets up to 60cm down remains a concern where found: mainly on N aspects in the alpine. We have seen a few human triggered avalanches in steep, isolated features such as moraines and glacier rolls over the past week.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Apr 8th, 2019 4:00PM