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 17th, 2020–Mar 18th, 2020

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

Regions

Purcells.

A ridge of high pressure has set in for the forecast period. Expect to see mainly sunny skies. Minimize exposure to steep slopes facing the sun during the hottest part of the day.

Confidence

High - Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

TUESDAY Night: Mostly clear, light northwest wind, alpine temperature -8 C.

WEDNESDAY: Mix of sun and cloud, light to moderate northwest wind, alpine temperature -2 C, freezing level 1900 m.

THURSDAY: Mix of sun and cloud, light west wind, alpine temperature -6 C, freezing level 1500 m.

FRIDAY: Mix of sun and cloud, light northwest wind, alpine temperature -3 C, freezing level 1700 m.

Avalanche Summary

On Monday there was a report of a skier remotely triggering (from a distance) a size 2 deep persistent slab avalanche at 2600 m on a northwest aspect. The avalanche was triggered from a thin spot, was 40-80 cm deep and ran on depth hoar near the base of the snowpack.

On the weekend there were reports of a few natural wind slab avalanches on the weekend size 1.5 to 2.5 on north and southeast aspects in the alpine. Additionally there were reports of several loose wet avalanches to size 1.5 from steep slopes facing the sun.

Snowpack Summary

Recent moderate to strong northeast and east wind has redistributed the snow and formed wind slabs at all elevations. New snow from last week may sit on a weak surface hoar layer and a sun crust on steep solar aspects. 

A weak layer of surface hoar buried February 22 may be found 50-100 cm deep. It may sit over a crust on solar aspects. Read more about surface hoar on our forecaster blog.

Deeply buried facets lurk near the bottom of the snowpack. This layer has been responsible for sporadic deep persistent slab avalanches, usually triggered from shallow, rocky start zones.

Terrain and Travel

  • Minimize exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
  • Cornices become weak with daytime heating.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.

Problems

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.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.