Northwest Inland

Good

Synopsis: A windy pacific storm is heading your way Saturday, clearing out Sunday.Saturday: 5 to 10 mm additional precipitation bringing storm totals in the range of 10 to 25 mm of water (somewhere around 15 to 30 cm of snow); Strong SW winds easing and veering W late in the day; freezing level below 500 m with alpine temperatures around -5Sunday & Monday: drier with less than 5 cm of snow; cooler temperatures with freezing level at the valley bottom and around -8 in the alpine;  light SW wind Saturday becoming light E wind on Monday.

On Wednesday, a snowmobile triggered a hard wind slab at Sinclair. It failed on the November crust/facet layer 30 cm above the ground. Evidence of a recent natural cycle was also reported. This deep crust/facet layer has been the failure plane for a number of large avalanches further to the west and was suspected to have failed at the Hankin-Evelyn area last weekend. Unfortunately, this weakness is unlikely to heal very quickly, so further deep avalanches are possible, especially as snow and wind-loading continue to stress the snowpack over the next few days.

Short-lived storm snow instabilities are likely to develop on steeper terrain as new snow continues to accumulate. But more importantly, forecast wind is sure to concentrate it and build deeper touchy windslabs; they may form lower down on slopes than typically expected. Older hidden windslabs from previous winds may still linger; remember that those winds blew from many directions so just about any exposed slope could harbour one. Spotty surface hoar is also buried in the upper snowpack, particularly in sheltered treeline areas. Of key concern is a November facet/crust layer which can be found near the base of the snowpack. This layer, which is widespread, can be triggered from thin-spot trigger points, or with a heavy load, such as storm slabs stepping down, cornice fall or a snowmobile. It has the potential for very large, destructive avalanches and demands respect. A rain crust is buried in the upper snowpack at low elevations. In general the snowpack is highly variable in depth due to windy conditions this season.