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 31st, 2018–Jan 1st, 2019

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

Regions

.

Happy New Year! New Year’s Day should be a beautiful day to be in the mountains. Don’t let the nice weather fool you. You may still trigger avalanches in wind loaded areas. In some locations wind deposited snow may sit on a layer of weak buried surface hoar. If an avalanche fails on this layer it may act in surprising ways.

Discussion

Avalanche and Snowpack Discussion:

Several natural and human triggered avalanches were reported in the Schriebers Meadows and Heather Meadows areas on Sunday. Many of these avalanches were unusual. They propagated widely, had thin crowns, released low on the slope, and/or failed on lower angled slopes. When we see signs like this, it screams buried surface hoar. Human triggered avalanches in other zones have failed on a similar layer.

 

12/30/18: Slab avalanches from Saturday’s storm. Many of these failed on a layer of buried surface hoar and propagated widely. Photo: Andrew Kiefer

If you use the nice weather to travel to higher elevations or into more remote areas, take time to stop and observe the snow. Due to stormy weather we have not received any information from higher elevations in quite some time.  

Snowpack Discussion

New Regional Synopsis Coming Soon

Problems

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.

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.