Avalanche Forecast

Issued: Mar 8th, 2019 4:00PM

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

tim haggarty, Parks Canada

Banff Yoho Kootenay.

More new snow has arrived than expected in most areas with touchy new slabs observed in the alpine. Expect conditions to have changed significantly from the last few weeks.

Summary

Weather Forecast

Much more snow than was expected arrived in the majority of the region Friday with moderate to strong SW - W winds. Saturday, look for winds to back off and snow to stop with partly cloudy skies remaining. Temperatures will be steady at around -10 to -15 at treeline through Saturday before warming about 5 degrees overall Sunday afternoon.

Snowpack Summary

A trace to 20 cm of new snow came with moderate to strong SW-W winds. This sits over weak surface facets, previous wind effect and crusts isolated to steep solar slopes. Weaker layers like the Jan.17 surface hoar/facets linger down 40-60 cm in some locations, but are currently lying dormant. A weak basal snowpack exists in thin snowpack areas.

Avalanche Summary

A flight in the Lake Louise area this morning saw several examples of loose dry avalanches running a good distance that had failed with the new loading. While only a few examples of fresh slabs were seen on the flight with poor visibility, the ski hills reported working with a touchy new slab up to 40 cm deep, up to 40m wide and running up to 150m.

Confidence

Due to the number of field observations on Friday

Problems

Loose Dry

Cold weather created weak, faceted surface snow. In steep terrain, these facets are easily triggered and can gain enough mass to affect skiers and climbers. The new snow and winds have triggered many events in the last 24 hrs.

Use caution above cliffs and terrain traps where small avalanches may have severe consequences.Good group management is essential to manage current conditions safely.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Wind Slabs

Touchy new slabs can be found in wind loaded areas up to 40cm thick. These slabs will be found sitting on the weak, faceted snow that was previously on the surface and we expect the bond to this snow to be poor.

Watch for surface cracking and stiffer surface layers of snow.The new snow will require several days to settle and stabilize.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 9th, 2019 4:00PM