Regions
South Coast Inland.
Stiff wind slabs may still be reactive to human triggers. Lingering reactive wind slabs are most likely in wind-loaded areas: below ridgelines, under cornices, and around steep, unsupported features.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
SUNDAY NIGHT: Clear with cloudy periods. Alpine temperatures near -17C. Ridgetop winds light from the east-northeast.MONDAY: Mix of sun and cloud with isolated flurries, up to 5 cm accumulation. Alpine temperatures near -17C. Ridgetop winds light to moderate from the northeast.TUESDAY: Cloudy with sunny breaks and isolated flurries, 5-15 cm accumulation with the larger snowfall amounts forecasted for the southern part of the forecast region. Alpine temperature near -20C. Ridgetop winds moderate from the northeast.WEDNESDAY: Sunny. Alpine temperatures near -13C. Ridgetop winds light from the northeast.
Avalanche Summary
Pockets of wind slab were reactive to skier traffic early in the week through Wednesday, when a few natural small wind slabs up to size 1 were reported in the northern part of the region. Most recently, loose dry sloughing snow was reported from steep, rocky features near ridge crest. There have been no recent reports of natural avalanches.
Snowpack Summary
Heavy wind transport has produced scoured surfaces, hard and soft wind slabs, sastrugi, and isolated pockets of soft faceted snow. Most high north-northeasterly aspects are scoured and wind buffed, sheltered areas holding less consolidated snow and more likely on south and west aspects. Widespread wind slabs have developed in the alpine and treeline with deeper deposits lower in start zones. Wind has affected all elevations including a surface wind skin at lower elevations.Anywhere from 0-60 cm of this wind affected snow sits on wind-pressed surfaces on northerly alpine features, and crust on most aspects and found with a mixture of weak feathery surface hoar and/or sugary facets in sheltered terrain at treeline and below. Cold temperatures have promoted surface faceting and are breaking down the buried crust. Below the recent wind affected snow and crust, another crust is found down 50-80 cm that formed mid-January right to mountain top on southerly aspects and on all aspects below 1700 m. Additionally at this depth, feathery surface hoar may be found in shady sheltered areas at treeline, but with little reactivity.The remainder of the snowpack is generally well-settled.
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.