Avalanche Forecast

The precipitation forecast for the East slope Cascades is tricky. Monitor weather and surface snow conditions carefully as you travel. Be ready to alter your plans based on conditions as they develop in front of you.

At higher elevations expect shallow wind slabs to develop throughout the day as more snow becomes available for transport.

Elsewhere, a mixture of rain, snow or possible freezing rain may develop moist to wet surface snow. Small loose wet avalanches may occur in isolated terrain features especially where soft surface snow existed prior to this storm.

Uncertainty still exists surrounding extent and sensitivity of the persistent weak layer in the Blewett Pass and Mission Ridge areas. This precipitation event will not be enough to test this basal layer with significant weight. Evidence and observations on this weak layer can be difficult to come by. Be prepared to adjust your travel to respect this low likelihood/higher consequence problem.

Despite all this new snow, early season hazards still exist. Many creek beds have still not filled in for the winter.

Recent mild weather, especially at higher elevations, has allowed for the strengthening of lingering wind slabs and upper snowpack weaknesses. Small isolated winds slabs have still been observed, however the extent of this problem continues to decrease.

Sun effected snow exists on sunny slopes. A mixture of moist snow and melt freeze crust may be found depending on elevation and timing.

Cold air trapped in the valleys has allowed for the development of surface facets and surface hoar in the below and near treeline bands especially on shaded slopes.  

Snowdepth decreases substantially the further east of the Cascade crest one travels. In many areas below treeline, there is not enough snow to present an avalanche danger. 

Observations

North

North Cascades Mountain Guides were in the Washington Pass area on Tuesday. They found steep southerly and westerly aspects getting significant sun effect above 5,000 feet with surfaces a mix of moist and melt/freeze depending on timing. They also found up to 1 cm surface hoar in avalanche terrain below the inversion layer (up to 5,400 ft).

Central

A NWAC forecaster was in the Diamond Head area of Blewett Pass on Tuesday. Basal facets (2-3mm) were found above 5000' on NW-N-E aspects. Large column tests showed this layer was reactive and likely to propagate. However, varied surface roughness combined with an overall shallow snowpack made for a low likelihood of finding the right terrain to support an avalanche. Just like the nearby Mission Ridge area, this layer will need to be watched moving forward. 

Other pertinent observations from the area include a rain crust observed up to 5400 feet. Snowdepths were low in this area, making backcountry travel difficult at lower elevations, wind scoured areas, and on sunny aspects.

Mission Ridge Pro Patrol reported avalanche control work within the ski area Saturday produced 1-4 ft wind slab avalanches. The larger avalanches released to ground on 1 mm basal facets.

South

No recent observations