We are approaching another flat line period in the forecast season. Its a good time to get out and do the longer classic tours with the longer days.
Weather Forecast
The temps will drop to -15 tonight with light winds at ridgetop. Tomorrow will see a mix of sun and cloud, no new snow and an alpine high of -7. The winds will be light at all elevations with variable directions. Even with the sun, we're expecting the freezing level to stay at valley bottom.
Avalanche Summary
No new observations today. Obscured skies for most of the day.
Snowpack Summary
Convective flurries and a mild upslope storm last night left variable amounts of new snow. On average the forecast region saw only 4cm's last night and another 3 throughout today. Not a huge change to the snowpack, but a slight refresh for sheltered areas. With the cooling temps, slabs in the alpine and upper treeline zones tightened up a bit. There are widespread windlabs in the alpine at the moment. For the most part these alpine slabs are well bonded, but in isolated areas(steep, immediate lee) there is a concern with a weaker midlayer within the slabs, down 20-30. Treeline also has windslabs, but these tend to be a bit softer and more focused to open areas. Sheltered areas have a light dusting with the new snow. Below treeline has seen little change except for the crusts freezing very well overnight.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.