We have the Oct layer back on the radar. It has evolved into a thick layer of sugary depth hoar at the base of the snowpack. Tomorrow is expected to be a clear and cool day. Great conditions for those longer spring trips.
Weather Forecast
Good news for the winter fans out there. The warm weather that was expected for tomorrow has been pushed back for a day. Tomorrow will see the cool air remain over us, -15 is the forecasted low for the alpine. Freezing level is expected to be 1300m at midday. No precip and clear skies. Light winds from the north.
Avalanche Summary
Some isolated loose dry avalanches involving the storm snow. Up to sz1 and out of steep terrain.
Snowpack Summary
Up to 15cm of snow fell last night as the cold front moved in. Today's temperatures were cool enough to keep this snow cold an dry. The only exception is low south aspects, these were softening by 1200hrs. The temperature/sun crust that has been building over the last while is widespread below treeline and stretches into the high treeline right now. Today on Tent Ridge we found a hint of the crust at 2300m. A profile at 2350m had a snowpack depth of 145cm with dense snow (1finger) for the top 100cm's. Below this, the snow character immediately turned to a loose mix of depth hoar and facets. We measured a moderate compression test, sudden collapse on this layer.
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.