Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Mar 11th, 2024–Mar 12th, 2024

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

Regions

Glacier.

Locally heavy snowfall delivered 20cm more than forecasted. Reactive storm slabs are present where wind has stiffened the snow surface at Alpine and Tree-line elevations.

Gusty winds tonight and more snowfall Tuesday will increase the avalanche danger.

Avalanche control in Rogers Pass is anticipated Tuesday.

Confidence

Moderate

Avalanche Summary

Natural avalanche activity in the hwy corridor picked up Mon morning with 20-30cm of snow and moderate SW winds. Avalanches to sz 2.5-3 were observed.

Last Thursday, we observed naturally-triggered size 3 slab avalanches from Catamount Mtn SE face and Mt. Leda NE face. These were both deep, likely failing on the Feb 3rd crust.

We continue to see daily reports in the region of human triggered avalanches on the Feb 3rd layer.

Snowpack Summary

A 30-40cm storm slab now rests upon variable old surfaces: a thin suncrust on South & West aspects; previous wind effect from variable winds in open terrain; and settled powder in sheltered areas.

80-140cm of settled snow sits atop a sugary facet layer. These facets are not bonding well to the widespread, very firm crust from Feb 3rd. This crust is a significant persistent weak layer and will be the main layer of concern for the foreseeable future.

Weather Summary

Continued unsettled weather, with flurries (locally heavy), gusty SW winds, and fluctuating freezing levels.

Tonight: Flurries, trace to 5cm, low -8°C, mod/strong S winds, FZL 700m.

Tues: Flurries, 5-10cm, Alp high -5°C, mod SW winds, FZL 1500m.

Wed: Mix of sun/cloud, isolated flurries, Alp high -8°C, light W winds, FZL 1300m.

Thurs: Sun/cloud, Alp high -4°C, light W winds, FZL 1500m

Terrain and Travel Advice

  • Watch for fresh storm slabs building throughout the day.
  • Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
  • Remote triggering is a concern, avoid terrain where triggering slopes from below is possible

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.