Avalanche Forecast
Jan 16th, 2019–Jan 17th, 2019
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
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The Bottom Line: New snow over the old surface will be the main concern. Light snow accumulations probably won't be enough to create much avalanche danger on Thursday, but avalanche danger will increase overnight and into Friday. Icy crusts may create challenging travel conditions.
Snow and Avalanche Discussion
The current snow surface is a mix of facets, crusts, and wind packed snow. On shaded aspects, weak snow on the surface is widespread in the area. We don’t have a great handle on the upper elevation extent of the weak snow in this area, but one observer reports skiing on a ‘glass carpet’ of surface hoar between 4,000 and 5,500ft. Another notes ‘dramatic faceting’ near and below treeline on shaded aspects. Folks speak of facet sluffs, a sure sign of very weak snow. As the snow accumulates into Friday, this will set the stage for our next round of avalanche activity.
New snow accumulations will be light on Thursday. However, we anticipate that whatever new snow does accumulate won’t bond well with the old surface. Continue to use standard practices and protocols for winter travel in the mountains. This includes minimizing exposure to the avalanche hazard and carrying standard rescue gear. Avalanches are unlikely, but not impossible. If you find more than 6” of new snow has drifted in or accumulated, it’s time to consider slab avalanches again. It's important to keep in mind the consequences of an avalanche in extreme terrain or that of a non-avalanche related injury or gear malfunction in a remote setting.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.