Northwest Coastal

Another day of strong sun and warm temperatures will maintain very dangerous avalanche conditions on Wednesday. Travel in avalanche terrain is not recommended.

Moderate -

Tuesday night: Clear. Light to moderate south winds. Freezing levels remaining near 2700 metres.Wednesday: Sunny. Light south or southeast winds. Alpine high temperatures around +8 with freezing levels of about 2800 metres, dropping slightly overnight.Thursday: A mix of sun and cloud. Moderate south winds. Alpine high temperatures around +5 with freezing levels around 2500 metres, remaining elevated overnight.Friday: Mainly cloudy with isolated rain showers or wet flurries beginning overnight. Moderate east winds. Alpine high temperatures around +6 with freezing levels around 2500 metres, dropping to about 1500 metres by mid-morning Saturday.

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. Remotely (from a distance) triggered avalanches have figured prominently in reports leading up to and during the current avalanche cycle. The March 10 interface has been the primary failure plane in slab releases.The heightened avalanche activity described above can be expected to continue while temperatures remain elevated and overnight cooling remains weak.

Between 50 and 100 cm of settled snow forms the upper snowpack, the product of storms since the drought ended on March 10. At lower elevations this precipitation came as rain. With the help of warming temperatures, this recent snow has settled into a slab that 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. In many areas the upper snowpack described above has become isothermal (slushy and cohesionless) as a result of warming.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. Both of these layers have produced recent avalanches and will remain a concern under the current warming pattern. The lower snowpack is generally strong.