Regions
Northwest Inland.
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
Synopsis: A frontal system will hit the coast early on Tuesday spreading moderate snow and increasing winds. This is followed closely by a second system late Wednesday. Tuesday: Light to locally moderate snowfall – 5-10 cm. The freezing level is around 600 m and winds increase to very strong from the south-southeast. Wednesday: Unsettled with light snow during the day and heavier snow in the evening (5-10 cm). The freezing level is steady near 600-700 m and winds remain strong from the south-southwest. Thursday: Light to moderate snow. The freezing level climbs closer to 1000 m.
Avalanche Summary
There are a few reports of size 1-2 natural wind slabs from immediate lee and cross-loaded features. Slope testing also resulted in a few size 1 slabs in steep wind-loaded features.
Snowpack Summary
A new sun crust has formed on steeper solar aspects. In shady areas there is 40-60 cm of well settled storm snow. Strong southwest winds formed touchy wind slabs in exposed terrain in lee of ridges, in gullies, and behind terrain features. There are a variety of old interfaces now down 60 - 100cm which include facets, crusts and isolated pockets of surface hoar. Recent observations indicate that these weaknesses have bonded fairly well now, but I still suggest digging and testing the snowpack to confirm.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow in northern and eastern parts of the region. Triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.
Problems
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.