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Avalanche Forecast

Archived

Mar 14th, 2023–Mar 15th, 2023

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Glacier.

Allow time for the new snow to bond before committing to bigger slopes.

Avoid thin areas where the deep persistent weakness will be closer to the surface and easier to trigger.

Confidence

Moderate

Avalanche Summary

Numerous natural avalanches size 2-3.5 were observed through the hwy corridor on Monday running far into the runout zones. Natural activity has subsided in the wake of the storm but human triggering remains possible.

Snowpack Summary

40cm of new snow on Monday fell on a variety of surfaces (wind affect, sun crust and/or surface hoar), this sits over a generally strong snowpack however the basal weakness of rounding facets/decomposing crust persists near the ground and should not be left out of your decision making.

Weather Summary

Calm weather will prevail for the remainder of this week with light to moderate winds and no significant precipitation.

Wed: Cloudy w/ sunny periods and isolated flurries, Alp low -12*C, moderate west winds, freezing level (FZL) 1100m

Thurs: mix of sun and cloud, no precipitation, Alp low -13*C, variable light winds, FZL 1300m

Fri: Cloudy w/ sunny periods, no precipitation, Alp low -10*C, light south winds, FZL 1600m

Terrain and Travel Advice

  • Closely monitor how the new snow is bonding to the crust.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.