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

Dec 17th, 2024–Dec 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 possible, human triggered probable.

Regions

Lizard-Flathead, Flathead, Lizard.

Avoid avalanche terrain during the storm, it will be very dangerous.

Confidence

High

Avalanche Summary

A natural avalanche cycle will occur on Wednesday.

A few small (size 1) slab avalanches were reported on Monday and over the weekend, along with other signs of instability indicating the surface hoar layer could be reactive when buried beneath a slab.

Snowpack Summary

15 to 25 cm of snow overnight and another 15 to 25 cm during the day will cause short-lived instabilities within the storm snow. Expect deep wind drifts at higher elevations.

A surface hoar layer, 20 to 40 cm deep prior to the storm, will be 50 to 80 cm deep by Wednesday afternoon. While its distribution is uncertain, it is expected to become reactive as a slab forms above it.

Treeline snow depths before the storm ranged from 100 to 150 cm.

Weather Summary

Tuesday Night

Cloudy with 15 to 25 cm of snow. 40 to 60 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Wednesday

Cloudy with 15 to 25 cm of snow. 60 to 80 km/h southwest ridgetop wind. Treeline temperature -2 °C.

Thursday

Mostly sunny. 20 km/h southwest ridgetop wind. Treeline temperature -3 °C.

Friday

Sunny. 30 km/h southwest ridgetop wind. Treeline temperature +2 °C. Freezing level climbing to 3000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Only the most simple non-avalanche terrain with no overhead hazard is appropriate at this time.
  • Storm slab size and sensitivity to triggering will likely increase through the day.

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.