Avalanche Forecast

Light snow showers should end Tuesday morning. A clearing trend should develop initially in the north Cascades Tuesday afternoon. But clouds can often linger at lower elevations along the east slopes in this pattern. Winds should be pretty light Tuesday with cold temperatures.

The avalanche danger is less than during the recent storm cycle but careful snowpack evaluation and cautious routefinding will still be essential on Tuesday.

Wind slab should be most likely to linger on north to southeast aspects due to recent southwest flow aloft. But watch for firmer wind transported snow on other aspects.

Storm slabs in many areas that had r sustained heavy snowfall should further settle on Tuesday.

There is still uncertainty regarding the regional extent, spatial variability and the stability of the potential December 8th persistent weak layer which would be buried at about 1-3 feet along the east slopes. Ratchet back your plans if you experience deep cracking, collapsing or whoomping. Some time and snowpack tests from many areas will be needed to determine is this layer is still a regional problem.

Loose dry avalanches will not be listed as an avalanche problem on Tuesday. But in steep terrain lacking a slab structure continue to watch for small loose dry avalanches near terrain traps like cliff bands where even small avalanches can have big consequences. 

With deep unconsolidated snow in many wind protected areas there remains a risk for tree well and snow immersion suffocation at this time. Ride or ski with a partner and keep them in sight at all times!

Watch for early season travel hazards at lower elevations such as barely covered rocks and open creeks.

The regional avalanche danger is expected to further slightly decrease on Wednesday. But it is expected that southeast to east winds will transport snow and build new wind slab on Wednesday.

Weather and Snowpack

Cold and fair weather early last week allowed for a sun crust to form on many solar aspects and for cold low density snow, near surface faceting and/or surface hoar to become fairly widespread.

These layers began to get buried in most areas on about December 8th when the latest storm cycle began starting with a couple day warming trend as southwest flow eroded an Arctic air mass over the Northwest. This initially buried the cold low density snow, near surface faceted snow and/or surface hoar with denser snow in most areas. The warming trend leveled off the past couple days. NWAC stations along the east slopes had about 1-3 feet of snowfall for the 4 days ending Monday morning.

Recent Observations

A regional avalanche cycle was seen Friday and Saturday with some avalanches releasing on the December 8th layer.

Observations from Washington Pass Saturday indicated about 12 inches of storm snow was still lacking much slab character but had gained minor slab stiffness in areas. One natural size 1.5 wind slab was noted releasing from below a ridge. No triggered slides were reported but some cracking was noted as the surface snow gained some cohesion.  The December 8th layer of buried surface hoar and/or buried near surface facets was about a foot down as of Saturday.

An observation for the Mission Ridge via the NWAC Observations tab for Sunday in the Lake Marion area indicates a right side up snowpack but also spatial variability and 10-35 cm wind slab giving shooting cracks on loaded slopes.

Pro-observer Jeff Ward was at Washington Pass on Sunday and  noted slightly increasing slab structure near ridges above about 7000 feet with some cracking and limited propagation when testing steep convex slopes.

The pro-patrol at Mission Ridge on Monday gave a very similar report to the Lake Marion report above, that of a generally shallow but stable snowpack but with spatial variation and where steep wind loaded on north to east slopes slopes had a sensitive snowpack.