Avalanche Forecast

Issued: Feb 28th, 2018 4:00PM

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

Jonas Hoke, Parks Canada

Jasper.

A weak and variable snowpack (from recent strong winds and cold temps) warrants a cautious approach.

Summary

Weather Forecast

Arctic air creeps into the region on Thursday and confronts the warmer low resulting in snow fall through Friday.Thursday: Cloudy with flurries (up to 5 cm). Alpine Low - 13C High -4C. Ridge wind light SE. Freezing level: 1600 meters.Friday: Flurries (up to 6 cm). Alpine Low -13 C, High -6 C. Ridge wind light SE. Freezing level: 1400 metres.

Snowpack Summary

Wind slabs and extensive wind effect found in all open areas. The upper snowpack is a 50 to 80 cm thick slab that sits on three weak layers in the mid-pack. The entire snowpack is faceting after two weeks of cold, dry weather. Whumpfing and collapses are more prevalent in the northern half of the forecast area.

Avalanche Summary

Isolated large Na avalanches were observed on a road patrol Wednesday, one windslab from a cross loaded pocket on a W aspect, and one persistent slab on an E aspect. Otherwise there has been minimal activity since the extensive avalanche cycle on February 8-9. Slopes that did not avalanche during this cycle should still be carefully assessed.

Confidence

Timing of incoming weather systems is uncertain

Problems

Persistent Slabs

A slab up to 80cm thick overlies: weak faceted crystals (well developed in shallow areas), surface hoar (at, and just above treeline), and sun crusts ( on steep S and W aspects). Faceting has reduced slab strength below treeline and in shallow areas.

Be wary of slopes that did not previously avalanche.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3.5

Wind Slabs

Previous wind effect will be difficult to assess under new snow. Expect hardslabs in the alpine and at treeline. The cold has reduced the tension in these but caution is still warranted, especially as new snow arrives over the next few days.

Best conditions on sheltered northerly aspects.If triggered the wind slabs may step down to deeper facet layers resulting in larger avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Mar 1st, 2018 4:00PM