Avalanche Forecast

Issued: Mar 18th, 2019 4:01PM

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

jsmith, Avalanche Canada

Purcells.

A widespread natural avalanche cycle is forecast to continue on Tuesday. Travel in avalanche terrain is NOT recommended.

Summary

Confidence

High -

Weather Forecast

NOTE: Freezing levels are forecast to remain elevated overnight throughout the forecast period. This will significantly increase the impact of day time warming on the snowpack.MONDAY NIGHT: Clear / Light, northeasterly winds / Alpine low 3 / Freezing level 3000 m.TUESDAY: Sunny / Light, northeasterly winds / Alpine high 7 / Freezing level 3000 m.WEDNESDAY: Sunny / Light, southeasterly winds / Alpine high 8 / Freezing level 3000 m.THURSDAY: Sunny / Light, westerly winds / Alpine high 7 / Freezing level 2700 m.

Avalanche Summary

On Sunday, a widespread loose wet avalanche cycle to size 2.5 and numerous size 3 persistent slabs were reported on solar aspects at all elevations. A natural avalanche cycle is expected to continue on all aspects and at all elevations on Tuesday.

Snowpack Summary

15-30 cm. of well settled snow has created a cohesive slab sitting on a pile of facets (sugary snow), as well as a crust on sun exposed slopes. Natural avalanches on this layer are expected to continue.At lower elevations below treeline, a weak layer of surface hoar (weak, feathery crystals) buried in mid-January can be found approximately 50-90 cm. deep and may be combined with a crust on south aspects. The current warming event may awaken this layer, resulting in large, destructive avalanches. Steep cutblocks and large open glades at lower elevations are the most likely places to trigger this layer. Smaller loose wet avalanches may "step-down" to this deeper layer.The base of the snowpack is composed of facets (weak, sugary snow) that sit on a crust. Very large avalanches failing on this persistent weak layer will become more likely with the intense sunshine and rising freezing levels.

Problems

Persistent Slabs

Warming temperatures have settled the recent storm snow into a cohesive slab sitting on weak facets (sugary snow) that is ripe for human triggers; especially at treeline and above.

Avoid steep terrain where the snow feels moist or slabby.Use extra caution on solar aspects where the new snow is sitting on a crust.Avoid convex slopes on rocky terrain with a variable snow depth.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1.5 - 3

Loose Wet

A widespread loose wet avalanche cycle has been occurring up to size 2.5. Natural loose wet avalanche activity is forecast to continue.

Avoid steep, sun exposed slopes when the solar radiation is strong.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Avoid re-grouping at the bottom of large avalanche paths.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Cornices

Sunshine and rising freezing levels will elevate the potential for cornice failures resulting in large avalanches.

Avoid exposure to cornices and sun exposed slopes when the solar radiation is strong.Cornice failures have the potential to trigger large avalanches on deeply buried weak layers.Cornices often break further back than expected; give them a wide berth when traveling on ridgetops.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1.5 - 3

Valid until: Mar 19th, 2019 2:00PM