Avalanche Forecast
Regions: Glacier.
Sunday's storm will bring snow to higher elevations and rain at and below Treeline.
For the die-hards out there, expect warm, mushy snow down low, while the Alpine should still sport some cold snow up high.
Confidence
Moderate
Avalanche Summary
Expect avalanche activity to increase on Sunday afternoon/evening as lower elevations get saturated by rain and higher elevations receive 10-15cm of snow and moderate winds.
No new avalanches were observed or reported for the last 3 days.
Snowpack Summary
Below treeline, a series of supportive crusts are present, but they break down with daytime warming/rain.
In the upper Treeline and Alpine, N'ly aspects hold dry snow. On solar aspects, a breakable crust overlies a series of buried crusts, which may provide a failure plane for slab avalanches as temps rise.
The Nov 17 basal weakness can still be found in many areas, ~20-40cm above the ground.
Weather Summary
A Spring storm, delayed by a day, hits Rogers Pass Sunday. 10-15cm is expected Sunday through early Monday morning, with mod/strong SW winds and freezing levels spiking around 2000m midday Sunday. Limited to no surface crust recovery expected Sunday night due to rain/cloud cover.
Terrain and Travel Advice
- Storm slab size and sensitivity to triggering will likely increase through the day.
- The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
- Avoid terrain traps such as gullies and cliffs where the consequence of any avalanche could be serious.
- If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Storm Slabs
10-15cm of snow will fall at higher elevations and will be deeper in wind loaded areas. On solar aspects it will fall onto a crust and may be quite reactive until it has time to bond. Conditions will change as you gain elevation or change aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2.5
Persistent Slabs
Up to 60cm of settled snow covers a series of crusts combined with surface hoar/facets in some locations. Loose wet avalanches in motion have the potential to step down to these layers, creating large avalanches.
Aspects: East, South East, South, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 3
Loose Wet
Lower elevations will see 10mm of rain, as the freezing level rises up to 1900m. The snowpack below treeline will lose strength and wet loose avalanches will become likely in steep terrain.
Aspects: South East, South, South West, West.
Elevations: Treeline, Below Treeline.
Likelihood: Likely
Expected Size: 1 - 2.5