Avalanche Forecast

Issued: Feb 26th, 2018 4:30PM

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.

tim haggarty, Parks Canada

Jasper.

A few cm of snow over the next few days will give the winds something to transport for the first time in a while. A conservative approach to terrain selection remains important with the existing weak snowpack structure.

Summary

Weather Forecast

NW flow to the upper atmosphere brings unsettled cool air to the region through Thursday.Tues: Cloudy with flurries (up to 5cm of snowfall). Alpine Low -16 C, High -12 C. Ridge wind light West (gusting strong)Wed: Cloudy with sunny periods and isolated flurries. Alp Low -15 C, High -12 C. Ridge wind light SW (gusting moderate)Thurs: Up to 10cm snow

Snowpack Summary

Old wind slabs and extensive wind effect found in open areas. The upper snowpack has settled to form a 50 to 80 cm slab that sits on three weak layers in the mid-pack which can be found throughout the forecast region, and produced many large avalanches during the Feb 8th cycle. The entire snowpack is faceting after two weeks of cold, dry weather.

Avalanche Summary

Helicopter patrol down highway 93 Sunday night noticed only a few recent windslabs in the alpine. There has been limited activity over that last two weeks following the extensive avalanche cycle on February 8-9 yet it is still prudent to treat slopes that did not avalanche during this cycle with a great deal of respect.

Confidence

Intensity of incoming weather systems is uncertain on Monday

Problems

Persistent Slabs

A 50 to 80cm thick slab, sits over sun Crusts (south and west aspects), Surface Hoar (at, and just above treeline) and weak Faceted Crystals (very developed in shallow snowpack features). Faceting has reduced slab strength in shallow and BTL areas.

Avoid shallow snowpack areas where triggering is more likely.Use conservative route selection, stick to supported terrain features, avoid overhead hazards.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3.5

Wind Slabs

Expect hardslabs in the alpine and a few softer slabs at treeline. The cold has kept these in check and helped them settle over the last few days but some caution is still warranted especially as new snow and winds arrive over the next few days.

The best powder will be found in sheltered locations at or below treeline.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 27th, 2018 4:00PM