Northwest Coastal

Slight cooling and increasing cloud may take the edge off loose wet avalanche problems on Thursday, but greenhouse effect may destabilize north aspects. It's still a tricky time to be in avalanche terrain. Get an early start if you're heading out.

Moderate -

Wednesday night: Clear. Light south winds. Freezing levels remaining near 2900 metres.Thursday: Mainly sunny with cloud increasing in the evening. Light to moderate south winds increasing over the day. Alpine temperatures dropping from about +5 to +1 as freezing levels descend from 2700 to 2300 metres.Friday: Cloudy with sunny periods and scattered rain showers or wet alpine flurries beginning in the evening. Light to moderate east winds. Alpine high temperatures around +5 with freezing levels to 2400 metres, dropping in the evening to 1500 metres by mid-morning Saturday.Saturday: Cloudy with wet flurries bringing up to 8 cm of new snow to higher elevations by end of day, easing overnight. Rain below about 1100 metres. Light southwest winds. Alpine high temperatures around -1 with freezing levels around 1500 metres.

Observations in the Skeena corridor and Shames area on Sunday through Tuesday have been showing evidence of the ongoing natural avalanche cycle affecting all aspects and elevations. Numerous natural loose wet avalanches continue to be observed, with some reaching size 3 (very large). Explosives control yielded slabs that initiated at the March 10 interface but gouged deeply into isothermal (slushy) and faceted (sugary) snow. Observations show the largest loose wet avalanches reaching the full extent of their respective avalanche paths.Initial reports of the avalanche cycle came from the Shames area on Sunday, with several very large (size 3) slab avalanches observed running full path with more numerous audible large avalanches. This initial activity was focused on steep, sun-exposed aspects. The March 10 interface has been the primary failure plane in slab releases.Avalanche activity has been similar if not more pronounced in the Bear Pass area and further north.Expect the heightened avalanche activity described above to continue while temperatures remain elevated and overnight cooling weak.

Between 50 and 100 cm of settled snow forms the upper snowpack at higher elevations, the product of storms since the drought ended on March 10. At lower elevations this precipitation came as rain. With the help of warm temperatures, this recent snow has either settled into a slab on shaded aspects or become increasingly isothermal (slushy) on sun-exposed aspects. Where it exists as a slab, it covers a variety of old snow surfaces left in the wake of the drought.  These include crusts on solar aspects, facets on shaded aspects at higher elevations, and surface hoar in shaded and sheltered locations. This variable layer has been the primary failure plane in recent slab avalanche observations.Not much further below this storm snow interface is a second weak layer buried on February 19, primarily made up of weak facets and surface hoar crystals. Recent loose wet and slab avalanches have been observed gouging into the faceted snow in this layer, thereby entraining additional mass.The lower snowpack is generally strong.