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Avalanche Forecast

Mar 11th, 2017–Mar 12th, 2017
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: South Rockies.

Conditions are tricky with a complex mix of avalanche problems and weather factors. Err on the side of caution when dealing with such uncertainty.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

SATURDAY NIGHT: Passing frontal system will bring 5-10 cm of new snow with strong southwest winds.SUNDAY: Light flurries easing off throughout the day, moderate southwest winds, alpine temperatures around -4 CMONDAY: Chinook conditions, cloudy with sunny breaks with possible flurries in the southeast part of the region, strong west winds, freezing level around 1900 m.TUESDAY: Cloudy with sunny periods, moderate southwest winds, freezing level around 2100 m.

Avalanche Summary

On Saturday, several loose wet avalanches were reported from steep solar aspects and a size 2 wind slab was reported on a windloaded ridge crest. On Thursday, explosive avalanche control along the White River (in the northwest corner of the region) produced over 10 deep persistent slab avalanches releasing on basal facets. Most of the avalanches were size 3, included several than ran full path to valley bottom taking out mature forest and blocking the river with up to 8 m of debris. An older size 2 natural avalanche failing on basal facets was also reported in the Crossing Creek area.New snow will form fresh storm slabs on Sunday, while warming and loading may stress deeper weaknesses and create the potential for large destructive avalanches.

Snowpack Summary

Warm temperatures from an alpine inversion have rapidly settled the most recent 20-30 cm of storm snow. March has delivered regular storms with roughly 50-90 cm of snow sitting above crust and facet interfaces from February. In some areas the snow above these interfaces may have a poor bond. The mid-pack in this region is generally strong, but the bottom third of the snowpack is composed of weak sugary facets roughly 1-1.5 metres deep. This remains a concern and should be on your radar, especially with the recent loading and upcoming warming.

Avalanche Problems

Storm Slabs

Another round of snow on Saturday night will form fresh storm slabs that will be thickest and most reactive in wind-exposed terrain.
Be cautious as you transition into wind affected terrain.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Be alert to conditions that change with elevation and time of day.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2

Deep Persistent Slabs

Storm loading and warming may increase the likelihood of triggering large deep persistent slab avalanches.
Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Avoid steep convexities or areas with a thin or variable snowpack.Watch for clues, like sluffing off of cliffs, that the snowpack is warming up.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3