Avalanche Forecast

Scattered showers should quickly taper off Monday morning and sunbreaks are likely through mid-day before cloud cover increases Monday afternoon ahead of the next frontal system. 

Persistent weak layers have had a decent test over the weekend from new loading. For slopes that have not released on these layers, the likelihood of natural triggering is decreasing, but the consequences are increasing as the slab depth increases. Storm slabs that step down to persistent weak layer depths could become large enough to bury, injure or kill.

Wind slab should be found mainly on lee northwest to east slopes near and especially above treeline. Generally avoid wind loaded slopes above treeline.  

Storm slabs should more cohesive and likely to trigger with day-time warming and sunshine on Monday. Choose lower angled slopes if you find sensitive storm layers.  

Small loose wet avalanches should be likely on steeper slopes below treeline involving small amounts of recent storm snow. Watch for loose wet avalanches near terrain traps, where even a small avalanche could have unintended consequences. 

There have been numerous reports of large tree bombs with the new snowfall and fluctuating snow levels. Look down at the snowpack but also at the hazard above! 

Two fair weather periods earlier this month allowed surface hoar and near surface faceting to occur. These persistent weak layers were buried on Jan 3rd and 11th intact and were reported around the east slopes. These weak layers are most likely to be found on non-solar (northerly) aspects and in the upper portion of the below treeline and the near-treeline elevation bands along the east slopes.  

The latest report via the North Cascades Guides is from Delancey Ridge on Wednesday where easily triggered wind slab of about 20-25 cm was seen on north and south slopes at about 6000 feet which was releasing on a persistent layer crust sandwich buried on January 11th. Natural avalanches were also heard in the area.

A couple reports are available for Thursday via the NWAC Observations page. Skiers triggered 10 inch slabs on a crust which may involve a persistent weak layer on north slopes at 6000 ft on Silver Star Mt. Snow pits near Leavenworth had a easy to spot persistent buried surface hoar layer at 35-40 cm from the surface.

On Saturday Mission Ridge pro-patrol found easy 6-8" ski cuts on lee aspects near and above treeline involving new storm snow.  It is thought that the buried surface hoar previously found in the Mission Ridge backcountry on northerly aspects was likely thoroughly tested earlier in the week and no longer a widespread issue in this specific area.  However, just east of Blewett Pass a surface hoar layer was identified 1/13 in snowpack tests via the NWAC observation page.

On Sunday, Scottish Lake High Camps reported a natural 12" slab release on a southerly aspect around 5000' and easily identified two buried surface hoar layers in N-NW snowpits at 5500 feet.