Avalanche Forecast

Significant precipitation and wind Friday night into early Saturday will continue to build wind and storm slabs at higher elevation. You will be able to trigger wind or storm slabs on open slopes greater than 35 degrees. Avalanches will likely be deeper in areas closer to the Cascade crest. Use visual clues such as blowing snow, fresh cornices, and uneven snow surfaces to identify and avoid wind loaded terrain. Fluctuating temperatures during the storm have created an “up-side-down” snowpack where heavy stronger snow sits on top of lighter weaker snow. This is a classic strong over weak slab scenario. This snowpack layering will exist in all avalanche startzones that are not stripped by the wind.

At lower elevations rain showers will create wet surface snow conditions. If you see new rollerballs, observe fan shaped avalanche debris, or experience prolonged rain, expect loose wet avalanches on slopes greater than 35 degrees. Some recent loose wet avalanches have run significant distances and entrained large amounts of snow. Even small loose wet avalanches can harm you if they carry you into terrain with higher consequences.

If the sun comes out or the clouds thin, snow conditions may change very quickly making it easier to trigger avalanches.

Several spring hazards exists in the mountains. Limit your exposure to large overhead cornices which may fail during periods of warming and rain. Creeks around the area are beginning to open as snow bridges thin and weaken. Choose travel routes carefully if you plan on traveling over larger creeks.

New snow began to accumulate in the Washington Pass area Friday afternoon. Light winds likely limited the initial development of new wind slabs in all but the most exposed locations. Washington Pass stayed just below freezing Friday afternoon maintaining snow at Pass level.

Generally warm weather over the earlier in the week allowed the upper snowpack to gain strength. Several freeze and thaw cycles likely created a strong surface crust in many locations.

We have very limited information about older persistent weak layers in the Washington Pass area. You are most likely to find a reactive persistent weak layer on shaded aspects or at higher elevations above recent rain events. If you have any information on snowpack conditions consider sharing your observations with NWAC on our public observations page.

Two common persistent weak layers seen in the Northeast Cascades are:

• 3/25 and 3/22: Buried surface hoar layers found on shaded aspects near and above treeline.
• 2/13 Facets above a firm and thick melt-freeze crust can be found in many locations near and above treeline. This layer is thought to be dormant at this time but may re-awaken with a substantial weather input.

Lower elevations further east of the crest have melted back for the season and no longer present an avalanche risk. 

Observations

On Friday, WA DOT reported several avalanches 3.5 feet deep near Cutthroat Peak as they cleared Highway 20. Although the exact weaklayer was not confirmed, the depth suggests an older persistent weak layer from mid-february.