Avalanche Forecast

Expect avalanche hazard Friday to develop in areas close to the Cascade crest where precipitation amounts will be higher. Farther east, avalanche hazard will be limited by lack of new precipitation.

If you see blowing snow, fresh cornices, or snow drifts stay, off of wind loaded slopes greater than 35 degrees. You are most likely to trigger a wind slab in exposed terrain below cornices, and on convex rollovers. Use visual clues such as uneven snow surfaces and drifts to identify wind loaded terrain.

At lower elevations, rain can quickly develop wet surface snow conditions. Avoid slopes greater than 35 degrees if you see new rollerballs, observe fan shaped avalanche debris, or experience periods of rain. Be cautious if you are traveling in terrain where even a small loose wet avalanche can have large consequences.

Several days of warm temperatures and cool nights has allowed recent wet snow instabilities to refreeze and gain strength. The upper snowpack is generally a combination of various melt-freeze layers and strong rounds.

In the mid and lower snowpack older persistent weak layers can still be found in some locations. You are most likely to find weak older snow at higher elevations and on shaded aspects where recent warm temperatures and rain have had minimal effects. You can use snowpack tests to identify buried persistent weak layers, however they are not a decision making tool. We have very limited information on the distribution of and sensitivity of any buried old weak layer. If you have any observations on these layers, please share them with NWAC on our public observations page.

Two common persistent weak layers seen in these zones 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 Wednesday, NWAC professional observer Matt Primomo traveled in Hawkins Mountain area. Below 5500 ft about 1 ft of wet surface snow was making Loose Wet avalanches possible on steep slopes. Above about 6000 ft firmer surface snow was limiting the Loose Wet avalanche potential. There were widespread large wet snow avalanches following the weekends storms. The upper two feet of snowpack has undergone a spring transition to melt-freeze grains.

On Monday, a public observation from the Entiat River drainage reported wet snow in the upper 16 inches (40 cm)  of the snowpack on a NE aspect at 6800 ft. Below this, colder drier snow was found with buried surface hoar 2 feet down (60 cm). This layer was reactive in snowpack tests, suggesting propagation was possible. The 2/8 crust was 3 feet (1 m) below the snow surface and breaking down. S through E aspects had a more springlike and consolidated snowpack.