Regions
Northwest Coastal.
Tricky winter conditions exist at higher elevations. Localized solar radiation, snow amounts and wind values may be higher than forecast. Avoid avalanche terrain during periods of heavy loading by snow, rain and wind.
Confidence
Fair - Due to the number of field observations
Weather Forecast
The current weather pattern is more winteresque than it has been all season. Im beginning to feel seasonally confused. The lull before the storm is over, and the next one arrives in coastal and inland regions late tonight. Wednesday will be fairly stormy with precipitation amounts 15-25 mm. Ridgetop winds will be strong from the SW and freezing levels will hover near 1100 m. On Thursday, 5-10 mm of precipitation is expected with continued strong west winds and freezing levels near 1000 m. The next bulk of precipitation comes Friday and hits mainly the coastal areas (around Terrace and west) with precipitation amounts up to 25 mm. Ridgetop winds will be moderate from the SW and freezing levels will rise to 1500 m. A strong upper level ridge looks to set up over the province through the weekend and remain stationary until Tuesday bringing warm air and clear, sunny skies.
Avalanche Summary
On Monday, explosive control showed numerous storm slab and wind slab avalanches up to size 2. These were primarily from N-NW aspects above 1300 m. With continued snow, rain, and strong winds natural avalanches and human triggered avalanches will likely continue on Wednesday. Lower elevations which have become rain soaked may see natural loose wet avalanches.
Snowpack Summary
At upper elevations 25- 40 cm of recent storm snow has blanketed the region. The new snow has been redistributed by strong south-west winds into wind slabs on leeward slopes and terrain features. With recent changing winds from the NE, you may find some reverse loaded pockets in unsuspecting places. The lack of bond between the new wind slabs and storm slabs over the older snow surfaces buried on April 9 th (surface hoar, crusts and facets) is the primary concern. The March 25th surface hoar / crust layer is reportedly unreactive, however; with the new load of wind and snow this should remain on your radar as it may re-awaken, initiating very-large and destructive avalanches. Moist- rain soaked snow exists at lower 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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.