Avalanche Forecast

Issued: Mar 10th, 2018 5:21PM

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

Ruari Macfarlane, Parks Canada

Waterton Lakes.

The first real Heat Wave of Spring - use increasing caution with rising temps into next week. Scale back your exposure to large slopes, consequential terrain, and cornices.

Summary

Weather Forecast

High pressure, clear skies, warm temps, and Light SW winds dominate the forecast period - expect strong solar input every day. Cool temps overnight Saturday, Freezing Level (FL) to Treeline Sunday. Cool again overnight Sunday, then FL into the Alpine Monday, staying high (warm) overnight, then soaring to mountaintop for Tuesday & beyond.

Snowpack Summary

10-15 cm of new snowfall from Friday night became moist on solar aspects up to treeline on Saturday. Light wind transport observed from the SW at ridges. On solar aspects the new snow overlies a crust 15cm down. The midpack is strong, but near the bottom of the snowpack is a weak layer of sugary facets; in deeper areas poorly bonded above a crust.

Avalanche Summary

On Saturday, a natural avalanche cycle was observed within recent storm snow, on steep slopes, all aspects and elevations. Both Loose Dry and Storm Slab avalanches, mainly Small (size 1) but a few Large (Size 2). Many occurred on solar aspects as cold new snow rapidly became Moist in the sun. More activity expected during warm temps Monday onward.

Confidence

Freezing levels are uncertain

Problems

Deep Persistent Slabs

The first sustained warming event of the season will put the deeply buried December Facet layer to the test. The 'where' and 'when' of this problem is difficult to evaluate, but likelihood will rise with the sustained warm temps forecast.

Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3.5

Loose Wet

More of a problem Tuesday on, especially if overnight temperatures remain high.

Avoid terrain traps, such as gullies, where the consequences of a small avalanche could be serious.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Cornices

Extra caution needed around cornices with current conditions.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Mar 13th, 2018 5:00PM