Avalanche Forecast

Another round of light to moderate snow showers Friday night should be followed by increasing shower activity Saturday afternoon and evening. Look for a relative break in precipitation from Saturday mid-morning through mid-day.  Areas outside of the Cascade Passes have already moderated temperature-wise while the Cascade Passes should experience a slow warming trend with the weakening of easterly flow late tonight and into Saturday.  

Once again, dangerous avalanche conditions may develop on Saturday as we look to tip the scales with additional light loading. Gradual warming will help new snowfall settle and perhaps develop more of a slab structure. Look for new wind slab near and above treeline in all zones. All aspects will be listed due to the ongoing reversal from easterly to westerly flow depending on location and elevation.

The upper portion of the below treeline and the near-treeline band should be the trickiest to navigate where persistent weak layers may have survived windy periods and become buried intact by recent light snowfall.

In steep sheltered terrain 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 is an increased 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!

Even though the lower part of the below treeline band is filling in, watch for early season travel hazards such as barely covered rocks and open creeks.

Weather and Snowpack

An active and cool weather pattern has resulted in a snowy December thus far with NWAC stations along the west slopes recording about 2-4 feet of snow.

Cold and fair weather was in place midweek allowing near surface faceting and/or surface hoar to become widespread. Beginning Wednesday night and continuing through Thursday, considerable wind transport from easterly winds occurred near and above treeline from Stevens Pass and south to the Crystal and Paradise environs. Less wind effect occurred in the Mt. Baker area. 

A switch to westerly flow occurred outside the Cascade Passes on Friday with moderate warming while the Passes stayed easterly and cold. Generally light snowfall accumulated Thursday night through Friday with the most at Mt. Baker and Paradise where roughly 9 inches of snow has accumulated through 5 pm. 

Prior to this new snow, the snowpack in non-wind affected terrain was generally right side up with low density snow at the surface and no problematic layers in the lower snowpack. 

Recent Observations

Widespread near-surface faceting and surface hoar formation has been observed throughout the west slopes including the Passes during the middle of the week along with some excellent ski conditions. Strong easterly winds built sensitive but shallow wind slabs roughly from Stevens Pass and south to White Pass on Thursday. We had confirmation of shallow and increasingly sensitive wind slab from Pro-observer Tom Curtis in the Jove Peak area near Stevens Pass Thursday on SW-SE aspects near treeline. Tom also noted a melt freeze crust overlying buried surface hoar just below the surface on N through SE aspects near treeline - a potential bed surface/weak layer interface. A similar report came from a solar slope in the Chair Peak area of Snoqualmie Pass Wednesday.

Light snowfall and/or localized shifting winds and warming Friday did not tip the scales and cause an uptick in reported avalanche activity. Most of the ski areas checked in today from Mt. Baker down to White Pass, and they generally noted shallow storm or wind slabs in their areas that were neither especially sensitive or widespread during control. Pro-observer Lee Lazzarra was in the Mt. Baker backcountry Friday and noted easy hand shears between the old snow/new snow interface but overall the new snow lacked a cohesive slab structure.