More snow than forecasted!!With new snow and moderate temps, the snowpack is reaching a tipping point. Expect buried surface hoar layers to become reactive. A conservative terrain choice is appropriate for the day.
Weather Forecast
Expect cloudy skies with periods of moderate snow flurries with accumulations up to 5cm over the day. The alpine high will be -5 with freezing levels reaching 1400m. Winds will be from the southwest in the 20km/hr range. Depending on which forecast you drink your morning coffee with, we are expected to receive 15-30cm of snow by Tuesday morning.
Snowpack Summary
30cm of storm snow now buries the Jan 4 surface hoar and a thin crust on solar aspects. The Dec 27 surface hoar is down ~50cm and the Dec 15 surface hoar is down ~70cm and still producing whumphing, cracking and small avalanches on unsupported terrain features at tree line and below.
Avalanche Summary
Numerous sz 1.5-2.5 avalanches observed in the past two days along the highway corridor from steep terrain. Test results show that the Jan 4 and Dec 27 surface hoar layers are becoming reactive, producing moderate sudden planar fractures in some profiles.
Confidence
Intensity of incoming weather systems is uncertain
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.