15cm of new snow is forecast overnight with strong SW winds. Be cautious of windslabs building in Alpine areas.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Friday
Weather Forecast
Forecast models are calling for snow overnight on thursday but amounts vary from 5-15cm. Winds are forecast to decrease into the light range by Friday under a sky that is likely to be a mix of sun and cloud. We may see some additional windslab development from the forecasted strong winds overnight on Thursday.
Avalanche Summary
No new avalanche activity was observed or reported on Thursday.
Snowpack Summary
10cm of new snow overnight gives up around 15-20cm of recent storm snow over the past 3 days. This snow has created pockets of windslabs in Alpine areas along ridgelines and in gullies. Otherwise our main concern os for the Oct 26th crust near the "base" of the current snowpack. This layer is down 40-50cm and has a weak facetted layer overlying it. Its likely to be a concern that we talk about for some time. IMPORTANT- Field observations are still very limited at this time.
Problems
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.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.