Forecasted amounts of precipitation spatially vary in the region. This forecast reflects areas that will receive the most amounts; possibly the East and South part of the region.
Confidence
Fair - Forecast snowfall amounts are uncertain for the entire period
Weather Forecast
Monday Night and Tuesday: The first of a series of systems approaching the interior is expected to start spreading precipitation over the region early Tuesday. Light to moderate precipitation amounts (more on the Eastern part of the region) are expected with strong SW winds . Freezing level will start rising to reach around 1600 m. and will stay high for the rest of the period.Wednesday: Precipitation easing off but still some moisture available. Winds are forecasted to be strong to extreme from the SW. Temperatures staying warm and freezing levels up to 1900 m. in the S part of the region. Thursday: Another burst of precipitation is expected with similar freezing levels and lighter winds switching from the SW.
Avalanche Summary
A couple natural slab avalanche size 2.5 were reported on W and SW slopes one of which was triggered by a loose avalanche.
Snowpack Summary
Up to 5 cm of new snow is covering a variety of surfaces; a 2 cm thick suncrust on SE-S-SW facing slopes at all elevation, a melt-freeze crust all the way up to 1600 m. and some well developed surface hoar on shaded slopes above that elevation. The forecasted precipitation and warm temperatures will add a significant load to the snowpack (possibly from 20 to 50 mm in water equivalent until Thursday). I suspect that the variety of surfaces described previously will become gradually more reactive as the load add up starting tomorrow. This could also awake the 60-90 cm deep persistent surface hoar layer that has been less reactive to skier traffic lately creating a potential for very large avalanches.
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.