Avalanche Forecast

Issued: Apr 11th, 2016 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 Loose Wet, Cornices and Wet Slabs.

Ruari Macfarlane, Parks Canada

Waterton Lakes.

A warm night on Monday will lead to the snowpack weakening quickly on Tuesday. Avalanche danger should drop steadily through the week with cooler temperatures. But, if we see 10cm+ of snow on Thursday, expect danger to rise again, with new Problems.

Summary

Weather Forecast

An approaching Pacific trough brings increasingly cool and unstable air. TUESDAY: Freezing level 2900m, dropping to 2400m. Increasing Cloud, moderate - strong SW winds. WEDNESDAY: Freezing Level 2000m, Cloudy, Strong SW winds easing. THURSDAY: Moderate upslope (Easterly) winds, easing, bring low cloud, cold temps, and light snowfall above 1600m.

Snowpack Summary

The snowpack is moist to wet in most areas. Strength depends on how well the surface crust recovers each night (expected poor on Tuesday). The snow will be strong while frozen, but increasingly weak with any sustained warm temperatures / during periods of strong sun. Wet Slab and glide avalanches, although Unlikely, are a concern all times of day.

Avalanche Summary

A widespread avalanche cycle (Cornice, Loose Wet, and Wet Slab avalanches, Size 1 - 2) occurred late Friday and Saturday with high freezing levels. This has slowed somewhat, but a few large natural avalanches were observed on Sunday (Loose Wet), and Monday (a Size 2.5 Cornice and Wet Slab avalanche). Many glide cracks exist - avoid these areas.

Confidence

Problems

Loose Wet

These may occur naturally, and be triggered by humans, during daytime warming on Tuesday. Watch your exposure, especially during sunny breaks. They should become unlikely later in the week.

Minimize exposure to steep slopes on warm or sunny days.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Cornices

Keep these in mind during daytime warming, particularly on Tuesday.

Minimize exposure to overhead hazard from cornices.Give cornices a wide berth when traveling on ridges.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Wet Slabs

Wet Slab avalanche timing is unpredictable. Although becoming unlikely late in the week, any Wet Slab avalanche will be large and destructive. Cracks in the slope (Glide cracks) are strong indicators of Wet Slab potential.

Avoid slopes with glide cracks.Avoid exposure to overhead slopes with Glide Cracks. Avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Apr 14th, 2016 4:00PM