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Avalanche Forecast

Archived

Mar 17th, 2024–Mar 18th, 2024

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
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

Purcells, Dogtooth, East Purcell.

⚠️ Avoid All avalanche terrain ⚠️Soaring freezing levels and solar radiation will likely continue to produce very large naturally triggered avalanches.

Check out our latest blog.

Confidence

High

Avalanche Summary

Numerous naturally triggered wet loose avalanches up to size 2.5 and persistent slab avalanches up to size 3.5 (very large) were reported on all aspects and elevations on Saturday.

Very large, natural avalanches are expected to continue to occur on Monday.

Snowpack Summary

High freezing levels overnight will result in no overnight re-freeze of the snow surface. As a result, the avalanche danger will rise rapidly throughout the day.

A widespread, hard crust down 40 - 110 cm with weak facets above continues to be the primary layer of concern for natural and human triggering of very large persistent slab avalanches.

Cornices have become large and looming, and are more likely to fail during periods of warming.

The bottom of the snowpack is generally weak and faceted, with the potential to produce very large avalanches. The most likely areas to trigger this deeply buried weak layer are steep, rocky areas in the alpine with a shallow or thin to thick snowpack.

Weather Summary

Sunday Night

Clear skies. 10 to 20 km/h west ridgetop wind. Treeline temperature 3 °C. Freezing level 2900 m.

Monday

Sunny. 10 to 20 km/h west ridgetop wind. Treeline temperature 8 °C. Freezing level 2900 m.

Tuesday

Mix of sun and cloud. 10 to 20 km/h southwest ridgetop wind. Treeline temperature 5 °C. Freezing level 2300 m.

Wednesday

Mix of sun and cloud. 30 to 40 km/h southwest ridgetop wind. Treeline temperature 4 °C. Freezing level 2200 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid all avalanche terrain during periods of intense solar radiation.
  • Only the most simple non-avalanche terrain free of overhead hazard is appropriate at this time.
  • Be aware of the potential for large, deep avalanches to run full path or even longer.
  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
  • Cornice failure may trigger large avalanches.

Problems

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.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.