Avalanche Warning Issued in the Cascades
The Northwest Avalanche Center (NWAC) has issued an Avalanche Warning for the west slopes of the Cascade Mountains and for Mt. Hood. The center says increasing heavy snow will put load onto weak layers formed during the recent cold temperatures. This will build unstable layers underneath the new snow and could create an avalanche.
Weak layers including faceted snow and a crust seen at Mt. Herman on Sunday. Photo by Simon Trautman from NWAC.
According to the NWAC, “pro-observer Simon Trautman was on Mt. Herman on Sunday and found a widespread weak surface snow sandwich that included faceted snow and a crust. These layers were giving highly reactive cracking and natural and triggered slab avalanches on steep slopes.”
Pro Obs: Despite good intentions to make it into the alpine today, strong northeast winds and rapidly forming wind slabs up high drove us from our objective before we even got our skins on. We shifted to more sheltered terrain but still observed the wind alternately scouring and loading slopes many Near Treeline areas – especially outside of the core Baker BC/Bagley Lakes area. Multiple snowpits still showed the presence of the December 8th facets and/or surface hoar – but this layer is becoming less reactive in testing. On the other hand the current snow surface is sprouting a whole new crop of weak surface snow than may become an issue with additional loading over the weekend. Lee Lazzara – December 16, 2016 #cascadewestnorthbaker @k2_skis @outdoorresearch @julbousa @lineskis @backcountryaccess
Pro Obs: Stevens Pass backcountry. Widespread surface hoar growth was observed today (Friday) on a variety of aspects and elevations. With the potential for light snowfall with light winds on Saturday this weak layer could get buried intact and become an issue in the future. If you are out Saturday before the snow starts falling it may be a good time to track where this layer is and where it is absent. Friday it was large and growing on everything except steep south facing slopes. Ski quality was quite good especially below treeline on shaded aspects. Watch out for isolated wind slabs near ridge crest. Jeff Ward 12/16/16
The NWAC also noted that “pro-observer Tom Curtis found weak faceted snow above the ground in a still fairly shallow overall snowpack in the Blewett Pass area Thursday. No observed avalanches were noted, but snowpack tests indicate the potential.”
In Montana, multiple natural avalanches have been observed on the steep slopes. The Gallatin National Forest Avalanche Center says the poor snowpack is still adjusting to the heavy snow received lately.
A poor snowpack structure is still adjusting to recent heavy snowfall and wind-loading. https://t.co/od5eRiVPHV
— GNF Avalanche Center (@AvalancheGuys) December 19, 2016
The Colorado Avalanche Information Center says there is a considerable avalanche concern above the treeline areas.
For WeatherNation: Meteorologist Mace Michaels