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 11th, 2019–Dec 12th, 2019

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

Regions

.

Expect dangerous avalanche conditions on Thursday. Strong winds along with heavy snowfall will create unstable snow at upper elevations. This potent storm will drastically change the previous snow cover. Even small avalanches can cause injury if you take a ride through shallowly buried rocks, stumps or other ground hazards.  

Discussion

We have limited information about the current snow and avalanche set up, but heres what we know: Washington pass did well with a few storms in late November, opening up opportunities to recreate on snow mainly near and above treeline. As of this writing, average snow depths of 15" to 30" can be found in the area. That is set to increase, perhaps double over the next couple of days. Along with potential instabilities within the storm layer, the snowpack structure does harbor some weak snow. The recently buried surface, and a layer of facets above a crust found roughly 12" up from the ground warrant closer inspection.  

On December 10th, an observer reported reactive conditions within a wind drift on a north facing slope at around 6,000ft. Check his recent observation here. On December 8th, test results indicated sudden failures 12" from the ground on a southeast facing slope at 7,000ft above Blue Lakes Trailhead on weak snow above a crust near the ground. On December 7, an observer found a natural slab that was triggered from loose snow just above Blue Lake on a north facing slope at 6,400ft. This appears to have occurred on the same layer. This is enough information to warrant suspicion of persistent layers, and bears consideration as the storm tapers off into the weekend. 

Snowpack Discussion

Regional Synopsis Coming Thursday, December 12, 2019

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.