Regions
Northwest Inland.
Forecast sun and high freezing levels may increase the danger from loose wet avalanches and avalanches stepping down to the deeply buried weak layer.
Confidence
Fair - Timing or intensity of solar radiation is uncertain on Wednesday
Weather Forecast
Overnight and Wednesday: Clear overnight with moderate Southerly winds and alpine temperatures near -15. Mostly sunny during the day with light South winds and no precipitation.Thursday: Sunny with moderate Northerly winds and temperatures of about -5 in the alpine.Friday: Mostly sunny with strong Northerly winds and cooler temperatures.
Avalanche Summary
Several small natural and rider triggered wind slabs were observed on Sunday. Loose snow sluffing was also reported on steep sheltered slopes. Forecast sunshine and warmer temperatures this week may be enough to make the mid February persistent weak layer become reactive.
Snowpack Summary
Outflow winds picked up late on Saturday and have likely resulted in reverse loading in exposed terrain. 35-90 cm of settled storm snow overlies a variety of old surfaces including weak facets, surface hoar (more predominant at tree line and below tree line elevations), a scoured crust, wind pressed snow, or any combination of these. Whumpfing, cracking, and reports from the field indicate a very poor bond between the new snow and these old surfaces. Recent snowpack tests give easy or moderate "pops or drops" shears on this persistent weakness and show potential for wide propagation. A lack of activity on this layer is likely because the overlying snow has not settled into a slab due to the recent cold temperatures.
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.
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.