Avalanche Forecast

The high pressure continues to sit stationary over the region through the weekend. Valley bottoms will remain cold while a strong temperature inversion with an above freezing layer will develop by Friday. Moderate to strong outflow winds will prevail in coastal valleys and cloud/ fog may accompany the strengthening temperature inversion as moisture becomes trapped. This high pressure  is forecast to last until at least Sunday. The warmest air will be at around 1800 m with temperatures reaching just above 5 degrees. The current weather pattern will start to see change by Monday or Tuesday.

On Wednesday no new avalanche observations were reported. However; I did notice a Facebook post on the Avalanche Canada page under visitor posts with a great photo of a size 2 slab avalanche failing on glacier ice from Finch Ridge. I don't know any other important details like time, date, aspect, elevation, or if it was a natural or rider triggered. Stiff wind slabs may remain sensitive to rider triggers and as the warm air aloft invades the region watch for obvious clues of instability like natural avalanche activity and moist/ wet snow surfaces, especially on southerly slopes. Smaller avalanches may also trigger deeper layers beneath the surface, initiating larger avalanches especially at higher elevations.

Monday's 10-20 cm of storm snow has seen some serious effects from the recent wind and cold temps. Northerly winds have likely built stiff wind slabs on southerly slopes and stripped snow from exposed aspects. These wind slabs may have a poor bond to the old surfaces that comprise of surface hoar, crusts ( up to 2100 m) and some dry facetted snow surfaces above 2100 m. Strengthening temperature inversions at upper elevations may start to deteriorate the snowpack, especially on southerly aspects. Watch for obvious signs of instability like moist and/or wet snow surfaces and snow balling. Where the buried crust is thick, avalanches failing on deeper layers beneath have become much less likely. My uncertainty lies at higher elevations where the buried crust doesn't exist and deeper persistent weak layers may, especially if the warming changes the upper snowpack structure and overload the buried weak layers where they exist. Reports indicate that these shears are resistant in the moderate to hard range but still have sudden fracture characteristics. I'd remain extra cautious as they may be sensitive to rider triggering.