Regions
Northwest Coastal.
Exercise caution during the brief lu
Confidence
Poor - Timing of incoming weather systems is uncertain on Wednesday
Weather Forecast
Synopsis: A return to a drier, colder, northwesterly flow will occur tonight. This is forecast to persist briefly until the next system hits the NW of the province. This system resembles the last and is expected to once again hammer the region with heavy precipitation.Tonight and Tuesday: Expect scattered flurries overnight, becoming heavy snow by Tuesday evening as the next system hits. The arrival of the cold front will keep freezing levels down around 600m. Ridgetop winds will be moderate from the south west. Wednesday: Temperatures will rise as the warm front pushes onto the coast. Freezing levels are expected to climb up to 1200m. The precipitation will be heavy in the morning but is expected to taper off later in the day. Winds will be strong from the west.Thursday: Periods of snow will persist through the day. Freezing levels are expected to remain high. Winds will be strong from the southwest
Avalanche Summary
Numerous slabs up to size 3 reported during the last 48 hours.
Snowpack Summary
Yesterday brought another 30 to 40cm to the region. The new snow settling rapidly due to the mild temperatures. We have no wind data from the region but given the expected strong to extreme winds we expect extensive wind slab formation in lee features. Total pre-storm snowpack depths in the region vary between 150 - 250cm. On December 20th Kasiks (Between Terrace & Rupert) picked up almost 50cm while Bear Pass saw around 20cm. This snow rests on a variety of old surface layers down between 80-140cm: old wind slabs, a couple of crusts and surface hoar/facets that formed in early December. The december week layers rests on stiff old wind slabs and melt freeze crust. Below this The mid pack is composed of deteriorating layers of old facets and crusts. A significant basal facet and crust combo lingers near the ground and is most prevalent on NW - E facing aspects at the upper TL and alpine elevations.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.