Avalanche Forecast

Dangerous avalanche conditions are developing on leeward aspects above treeline on Wednesday morning in the Cascade East-North Zone. Moderate W-SW winds were transporting low density snow on Friday morning near and above treeline and will continue to transport snow onto leeward aspects on Friday. These wind slabs are expected to be sensitive to human trigger given the weaker snow existing above the 2/5 crust and will become increasingly widespread above treeline, with wind slabs confined to more specific terrain below treeline. Avoid slopes onto which you see active snow transport. Fresh, soft cornices and snow drifts also indicate that wind slabs are present in nearby terrain. Use visual clues to help you identify wind slabs and select safer travel routes. Remember to give wind loaded areas a margin of safety as small natural wind slab avalanches are possible.

The new snow is poorly bonded to the old snow surface. Small loose dry avalanches will still be possible until this bond improves. Avoid steep slopes above terrain where even a small avalanche may have large consequences such as above cliffs, rocks, and open creeks.

In some locations snow fell on a firm icy surface crust. Be careful if traveling on steep firm slopes where stopping a fall will be very difficult.

Generally the east slopes of the Cascades saw minimal weather inputs on Thursday. Anywhere from 2-8" of snow has fallen on the 2/5 crust with the highest amounts in the north and closer to the crest. The most recent few inches of snow fell on Wednesday. Newer storm snow bonded poorly to the old snow. A wide variety of old surfaces include melt-freeze crust on sun exposed slopes, weak surface facets and surface hoar in sheltered areas (identified on NE through E aspects in the Washington Pass area above 6500 ft), and wind textured snow on exposed features.

Above treeline, winds from earlier in the week drifted snow forming small shallow wind slabs on lee slopes and scouring windward surfaces to the crust.

Below the old snow surface a relatively well consolidated snowpack exists. While we are tracking several older crust layers there are currently no significant layers of concern in the snowpack.

In the last week of January, observers reported isolated buried surface hoar on top of the 1/16 crust. This persistent weak layer was found or thought to be the cause of several avalanches. A recent observation (2/11) from the Mission Ridge area confirmed this layer is still present in some locations. Although it is not a main concern on Friday, use caution when traveling in areas further east of the crest where this layer may survive. This layer will be worth watching during a larger storm slated for the region on Saturday. Snow profiles and snowpack tests are the best means to confirm the presence of this layer.

Observations

North

NCMG reported on Friday morning that winds were blowing snow near Harts Pass.

Avalanche professionals in the Cascade East-North zone Thursday triggered small loose dry avalanches. This was due to 2-4" of low density snow over the 2/5 crust. Wind slabs found to be small, isolated, and very close to ridges.One team was able to trigger a small pocket of wind slab 4 inches deep at 8700 ft on a steep north-facing aspect.

Over the last several days, avalanche professionals in the Washington Pass area reported recent winds have created a variety of snow surface conditions above treeline. On Sunday, observations from professionals near Hart's Pass noted surface hoar up to 1 cm thick on all aspects up to a few hundred feet below ridgecrest. 

Central

A recent observation from the Mission Ridge/Lake Clara area.