Avalanche Forecast

Avalanches may begin on northeast to east aspects early in the day and continue onto south, westerly and northwesterly aspects as the day wears on. With each day, you may see avalanches grow larger and at higher elevations and on all but direct north aspects at high elevations. Look for signs of instability such as wet, heavy surface snow, rollerballs, and fan-shaped avalanches. If you notice these clues, avoid going on or under steep slopes where loose wet slides may run naturally. 

It's a good idea to choose conservative terrain, or just stay out of the mountains until we get a solid freeze. Many slopes have produced wet avalanches, but until every steep slope has run, theres potential for more with this weather. Some slides may be quite large, gouging into old snow layers, or running on the ground. Take note of how much the sun is affecting slopes by aspect, elevation, and slope angle to help you assess which slopes may be most problematic on a given day. If you do choose to go into the backcountry during these times of transition, get out of the mountains early, stay off steep slopes as soon as any superficial crust begins to break down, and watch your overhead hazard as cornices pose a very real threat.

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.

Record warm temperatures are following an extended snowy and cold period. The snowpack has many layers that could begin to "wake up" as meltwater percolates down to them. One of the more concerning layers are the facets underneath a thin crust that was buried in early February. As each day warms and only superficial refreezes occur, larger and more dangerous avalanches may become more likely. The poor snowpack structure with well defined facets leads us to think that unpredictable slabs are possible. This will be the third day in a row with a poor overnight freeze, sometimes considered the magic number for widespread wet slab activity. 

These avalanches are notoriously difficult to predict. When they do happen, they can be large and destructive. You can check how deep water is traveling through the snowpack by digging and looking for moist layers of snow. As day-time temperatures warm, stay off of and out from under large sun-exposed avalanche start zones, unsupported slopes, and terrain over 30 degrees where meltwater is reaching buried weak layers.

Release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slab avalanches can be very destructive.

Avoid terrain where and when you suspect Wet Slab avalanche activity. Give yourself a wide safety buffer to handle the uncertainty

A Wet Slab avalanche. In this avalanche, the meltwater pooled above a dusty layer of snow. Note all the smaller wet loose avalanches to either side.

Wet slabs occur when there is liquid water in the snowpack, and can release during the first few days of a warming period. Travel early in the day and avoiding avalanche paths when you see pinwheels, roller balls, loose wet avalanches, and during rain-on-snow events.