Avalanche Forecast

We’re expecting a storm total 12-16” which redistributes with strong winds as it falls to form reactive wind slabs. Snowfall intensity peaks during the evening hours and tapers to light snow or snow showers from midnight into Wednesday morning. Strong winds might have loaded some of these slopes well below the typical start zones.  Wind-affected snow may lie above firm or breakable sun melt-freeze crusts on W-S-E aspects, providing a bed surface for slabs to run on. Give the slabs time to bond to the old interface and consolidate. Adopt a conservative approach, particularly first thing in the morning when the avalanche danger is highest, avoiding all slopes steeper than 35 degrees. 

In wind-protected areas or below treeline you may find a storm slab problem. We think winds on Tuesday likely destroyed observed surface hoar, but it could be preserved in some areas. Check the bond at the new/old snow interface on multiple aspects before moving onto sheltered, supported terrain steeper than 35 degrees, avoiding convex rollovers.

Fresh or recent avalanche debris, shooting cracks, whumphing, firm or punchy snow layers all confirm a slab avalanche problem in your terrain and remind you to dial it back.

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.

Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..

Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

Cool temperatures are not expected to be able to stave off the March sunshine when it makes an appearance, but with lingering clouds gradually dissipating, we're not sure exactly when that will occur. Expect signs of instability to originate off of warming rocks, tree shedding snow, or rollerballs. Point releases gain mass as they go, potentially moving all the storm snow down to the 3/9 sun crust. Don't linger on or under slopes receiving direct sunshine. Instead, plan for the potential that east-facing slopes destabilize in the morning, S facing slopes between 10 and 3 PM, and west-facing slopes between 11 and 4 PM.

Remember that large cornices loom on most high ridges. Use caution to not travel on or underneath overhung cornices.

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. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. 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.

Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.

Several loose wet avalanches, and lots of pinwheels and roller balls.

Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.