Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Glacier.
Tread cautiously in the hills today. Cold temp's should tighten the snowpack, but sunshine on steep southerly aspects may cause a natural avalanche cycle.
Weather Forecast
A short-lived high-pressure ridge sits over us today. Cooler temp's (-11°c in alpine), light ridge-top winds, and plenty of sunshine on Saturday. Slightly warmer on Sunday and Monday (-7°cin alpine), with isolated flurries and light to moderate SW winds.
Snowpack Summary
50cm+ of storm snow has settled into a surface slab at all elevations. Cooler temp's may make it stubborn to trigger. The Dec 9 surface hoar/facet/crust persistent weak layer is buried 90cm+ and is producing large whumphs and sudden planar results. The Nov 21 surface hoar/facet persistent weak layer is down ~140cm.
Avalanche Summary
A widespread natural avalanche cycle to sz 3-3.5 occurred Thursday night with the strong/extreme SW winds. Artillery control during the day produced avalanches from sz 2 to 3.5 in the highway corridor. Avalanche debris from Dispatcher's Bowl and Grizzly Peak was observed at valley bottom and across Connaught Creek, large sz 3.5's from the storm.
Confidence
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
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.