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East Slopes Central - Lake Chelan to South of I-90

Issued: 6:00 PM PST Monday, January 1, 2018
by Dennis D'Amico

NWAC avalanche forecasts apply to backcountry avalanche terrain in the Olympics, Washington Cascades and Mt Hood area. These forecasts do not apply to developed ski areas, avalanche terrain affecting highways and higher terrain on the volcanic peaks above the Cascade crest level.

While wind slabs will continue to stabilize, recent cool weather may cause this process to take longer than usual. Keep an eye out for signs of recently wind transported snow.

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Avalanche Problems for Tuesday

Wind Slabi

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

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Forecast for Tuesday:

Mostly cloudy and mild weather on Tuesday will continue to allow wind slabs to gain strength. Expect colder temperatures and valley clouds to limit warming at lower elevations.

Look for areas of recently wind transported snow such as uneven snow surfaces, fresh cornices and snow drifts. Identify and avoid areas of wind loaded snow. Recent strong winds may have loaded slopes well below ridge crest. Pay attention to exposed terrain features even below tree line where wind slabs may have formed.

Wind slabs can be deceptively difficult to manage in the terrain. Take a moment and read our recent blog post by NWAC Pro Observer Jeremy Allyn on wind slabs.

Cornices along ridge crest have grown larger especially at higher elevations. Remember to give these features a wide berth. Cornices can break much farther back from the ridge than expected.

Despite recent snow, early season conditions still exist. Pay particular attention to open creeks that have not filled in for the season.

Avalanche Summary:

Happy New Year from your friends at the Northwest Avalanche Center.

Cool weather east of the Cascades has slowed the stabilization of wind and storm slabs formed during the recent active weather pattern. However, on Monday warmer air finally worked it's way aloft with higher elevation stations such as Lyman Lake, Mission Ridge and Dirty Face warming well above freezing while lower elevations stayed in the freezer (see graph below).

 

Winds over the past several days formed firm and initially reactive wind slabs on a variety of aspects.

Storm totals from across the area show 1 - 2 feet of snow (highest storm totals Lake Wentachee and Holden) fell during the series of storms ending Saturday. Layers within the storm snow have been reported from around the area, but trends continue to show these layers slowly gaining strength.

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 Cascade Mountain Guides were in the Washington Pass area Friday through Sunday. By Sunday, sensitive storm slab layers and avalanches seen Friday were gaining strength and becoming unlikely to trigger.  Wind slabs were thought to be stubborn but were still avoided or approached cautiously above treeline. One natural cornice release was observed on Sunday. 

Central

Mission Ridge Pro Patrol reported very sensitive wind slabs observed around the area Saturday. A natural avalanche cycle was observed from Friday night. Avalanche control work within the ski area Saturday produces 1-4 ft wind slab avalanches. The larger avalanches released to ground on 1 mm basal facets, representing a potential local persistent slab problem in the Mission Ridge area that will need to be watched. 

On Friday, a public skier triggered a 16-18” wind slab in closed terrain of Mission Ridge Ski area on a NE aspect at approximately 6000’. The skier was not caught nor injured.

South

No recent observations

No Corresponding Mountain Weather Forecast Available

USE AT YOUR OWN RISK

This Backcountry Avalanche Forecast is provided in conjunction with the US Forest Service, and is intended for personal and recreational purposes only. Safe backcountry travel requires preparation and planning, and this information may be used for planning purposes but does not provide all the information necessary for backcountry travel. Advanced avalanche education is strongly encouraged.

The user acknowledges that it is impossible to accurately predict natural events such as avalanches in every instance, and the accuracy or reliability of the data provided here is not guaranteed in any way. This forecast describes general avalanche conditions and local variations will always occur. This forecast expires 24 hours after the posted time unless noted otherwise.